2 * Copyright (c) 2009-2012 Spectra Logic Corporation
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions, and the following disclaimer,
10 * without modification.
11 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
12 * substantially similar to the "NO WARRANTY" disclaimer below
13 * ("Disclaimer") and any redistribution must be conditioned upon
14 * including a substantially similar Disclaimer requirement for further
15 * binary redistribution.
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
27 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGES.
30 * Authors: Justin T. Gibbs (Spectra Logic Corporation)
31 * Ken Merry (Spectra Logic Corporation)
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
39 * \brief Device driver supporting the vending of block storage from
40 * a FreeBSD domain to other domains.
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/kernel.h>
46 #include <sys/malloc.h>
51 #include <sys/devicestat.h>
53 #include <sys/fcntl.h>
54 #include <sys/filedesc.h>
56 #include <sys/module.h>
57 #include <sys/namei.h>
60 #include <sys/taskqueue.h>
61 #include <sys/types.h>
62 #include <sys/vnode.h>
63 #include <sys/mount.h>
64 #include <sys/sysctl.h>
65 #include <sys/bitstring.h>
68 #include <geom/geom.h>
70 #include <machine/_inttypes.h>
73 #include <vm/vm_extern.h>
74 #include <vm/vm_kern.h>
76 #include <xen/xen-os.h>
77 #include <xen/blkif.h>
78 #include <xen/gnttab.h>
79 #include <xen/xen_intr.h>
81 #include <xen/interface/event_channel.h>
82 #include <xen/interface/grant_table.h>
84 #include <xen/xenbus/xenbusvar.h>
86 /*--------------------------- Compile-time Tunables --------------------------*/
88 * The maximum number of outstanding request blocks (request headers plus
89 * additional segment blocks) we will allow in a negotiated block-front/back
90 * communication channel.
92 #define XBB_MAX_REQUESTS 256
95 * \brief Define to force all I/O to be performed on memory owned by the
96 * backend device, with a copy-in/out to the remote domain's memory.
98 * \note This option is currently required when this driver's domain is
99 * operating in HVM mode on a system using an IOMMU.
101 * This driver uses Xen's grant table API to gain access to the memory of
102 * the remote domains it serves. When our domain is operating in PV mode,
103 * the grant table mechanism directly updates our domain's page table entries
104 * to point to the physical pages of the remote domain. This scheme guarantees
105 * that blkback and the backing devices it uses can safely perform DMA
106 * operations to satisfy requests. In HVM mode, Xen may use a HW IOMMU to
107 * insure that our domain cannot DMA to pages owned by another domain. As
108 * of Xen 4.0, IOMMU mappings for HVM guests are not updated via the grant
109 * table API. For this reason, in HVM mode, we must bounce all requests into
110 * memory that is mapped into our domain at domain startup and thus has
111 * valid IOMMU mappings.
113 #define XBB_USE_BOUNCE_BUFFERS
116 * \brief Define to enable rudimentary request logging to the console.
120 /*---------------------------------- Macros ----------------------------------*/
122 * Custom malloc type for all driver allocations.
124 static MALLOC_DEFINE(M_XENBLOCKBACK, "xbbd", "Xen Block Back Driver Data");
127 #define DPRINTF(fmt, args...) \
128 printf("xbb(%s:%d): " fmt, __FUNCTION__, __LINE__, ##args)
130 #define DPRINTF(fmt, args...) do {} while(0)
134 * The maximum mapped region size per request we will allow in a negotiated
135 * block-front/back communication channel.
137 #define XBB_MAX_REQUEST_SIZE \
138 MIN(MAXPHYS, BLKIF_MAX_SEGMENTS_PER_REQUEST * PAGE_SIZE)
141 * The maximum number of segments (within a request header and accompanying
142 * segment blocks) per request we will allow in a negotiated block-front/back
143 * communication channel.
145 #define XBB_MAX_SEGMENTS_PER_REQUEST \
147 MIN(BLKIF_MAX_SEGMENTS_PER_REQUEST, \
148 (XBB_MAX_REQUEST_SIZE / PAGE_SIZE) + 1)))
151 * The maximum number of shared memory ring pages we will allow in a
152 * negotiated block-front/back communication channel. Allow enough
153 * ring space for all requests to be XBB_MAX_REQUEST_SIZE'd.
155 #define XBB_MAX_RING_PAGES \
156 BLKIF_RING_PAGES(BLKIF_SEGS_TO_BLOCKS(XBB_MAX_SEGMENTS_PER_REQUEST) \
159 * The maximum number of ring pages that we can allow per request list.
160 * We limit this to the maximum number of segments per request, because
161 * that is already a reasonable number of segments to aggregate. This
162 * number should never be smaller than XBB_MAX_SEGMENTS_PER_REQUEST,
163 * because that would leave situations where we can't dispatch even one
166 #define XBB_MAX_SEGMENTS_PER_REQLIST XBB_MAX_SEGMENTS_PER_REQUEST
168 /*--------------------------- Forward Declarations ---------------------------*/
172 static void xbb_attach_failed(struct xbb_softc *xbb, int err, const char *fmt,
173 ...) __attribute__((format(printf, 3, 4)));
174 static int xbb_shutdown(struct xbb_softc *xbb);
175 static int xbb_detach(device_t dev);
177 /*------------------------------ Data Structures -----------------------------*/
179 STAILQ_HEAD(xbb_xen_req_list, xbb_xen_req);
182 XBB_REQLIST_NONE = 0x00,
183 XBB_REQLIST_MAPPED = 0x01
186 struct xbb_xen_reqlist {
188 * Back reference to the parent block back instance for this
189 * request. Used during bio_done handling.
191 struct xbb_softc *xbb;
194 * BLKIF_OP code for this request.
199 * Set to BLKIF_RSP_* to indicate request status.
201 * This field allows an error status to be recorded even if the
202 * delivery of this status must be deferred. Deferred reporting
203 * is necessary, for example, when an error is detected during
204 * completion processing of one bio when other bios for this
205 * request are still outstanding.
210 * Number of 512 byte sectors not transferred.
212 int residual_512b_sectors;
215 * Starting sector number of the first request in the list.
217 off_t starting_sector_number;
220 * If we're going to coalesce, the next contiguous sector would be
223 off_t next_contig_sector;
226 * Number of child requests in the list.
231 * Number of I/O requests still pending on the backend.
236 * Total number of segments for requests in the list.
241 * Flags for this particular request list.
243 xbb_reqlist_flags flags;
246 * Kernel virtual address space reserved for this request
247 * list structure and used to map the remote domain's pages for
248 * this I/O, into our domain's address space.
253 * Base, psuedo-physical address, corresponding to the start
254 * of this request's kva region.
259 #ifdef XBB_USE_BOUNCE_BUFFERS
261 * Pre-allocated domain local memory used to proxy remote
262 * domain memory during I/O operations.
268 * Array of grant handles (one per page) used to map this request.
270 grant_handle_t *gnt_handles;
273 * Device statistics request ordering type (ordered or simple).
275 devstat_tag_type ds_tag_type;
278 * Device statistics request type (read, write, no_data).
280 devstat_trans_flags ds_trans_type;
283 * The start time for this request.
285 struct bintime ds_t0;
288 * Linked list of contiguous requests with the same operation type.
290 struct xbb_xen_req_list contig_req_list;
293 * Linked list links used to aggregate idle requests in the
294 * request list free pool (xbb->reqlist_free_stailq) and pending
295 * requests waiting for execution (xbb->reqlist_pending_stailq).
297 STAILQ_ENTRY(xbb_xen_reqlist) links;
300 STAILQ_HEAD(xbb_xen_reqlist_list, xbb_xen_reqlist);
303 * \brief Object tracking an in-flight I/O from a Xen VBD consumer.
307 * Linked list links used to aggregate requests into a reqlist
308 * and to store them in the request free pool.
310 STAILQ_ENTRY(xbb_xen_req) links;
313 * The remote domain's identifier for this I/O request.
318 * The number of pages currently mapped for this request.
323 * The number of 512 byte sectors comprising this requests.
328 * BLKIF_OP code for this request.
333 * Storage used for non-native ring requests.
335 blkif_request_t ring_req_storage;
338 * Pointer to the Xen request in the ring.
340 blkif_request_t *ring_req;
343 * Consumer index for this request.
345 RING_IDX req_ring_idx;
348 * The start time for this request.
350 struct bintime ds_t0;
353 * Pointer back to our parent request list.
355 struct xbb_xen_reqlist *reqlist;
357 SLIST_HEAD(xbb_xen_req_slist, xbb_xen_req);
360 * \brief Configuration data for the shared memory request ring
361 * used to communicate with the front-end client of this
364 struct xbb_ring_config {
365 /** KVA address where ring memory is mapped. */
368 /** The pseudo-physical address where ring memory is mapped.*/
372 * Grant table handles, one per-ring page, returned by the
373 * hyperpervisor upon mapping of the ring and required to
374 * unmap it when a connection is torn down.
376 grant_handle_t handle[XBB_MAX_RING_PAGES];
379 * The device bus address returned by the hypervisor when
380 * mapping the ring and required to unmap it when a connection
383 uint64_t bus_addr[XBB_MAX_RING_PAGES];
385 /** The number of ring pages mapped for the current connection. */
389 * The grant references, one per-ring page, supplied by the
390 * front-end, allowing us to reference the ring pages in the
391 * front-end's domain and to map these pages into our own domain.
393 grant_ref_t ring_ref[XBB_MAX_RING_PAGES];
395 /** The interrupt driven even channel used to signal ring events. */
396 evtchn_port_t evtchn;
400 * Per-instance connection state flags.
405 * The front-end requested a read-only mount of the
406 * back-end device/file.
408 XBBF_READ_ONLY = 0x01,
410 /** Communication with the front-end has been established. */
411 XBBF_RING_CONNECTED = 0x02,
414 * Front-end requests exist in the ring and are waiting for
415 * xbb_xen_req objects to free up.
417 XBBF_RESOURCE_SHORTAGE = 0x04,
419 /** Connection teardown in progress. */
420 XBBF_SHUTDOWN = 0x08,
422 /** A thread is already performing shutdown processing. */
423 XBBF_IN_SHUTDOWN = 0x10
426 /** Backend device type. */
428 /** Backend type unknown. */
429 XBB_TYPE_NONE = 0x00,
432 * Backend type disk (access via cdev switch
435 XBB_TYPE_DISK = 0x01,
437 /** Backend type file (access vnode operations.). */
442 * \brief Structure used to memoize information about a per-request
443 * scatter-gather list.
445 * The chief benefit of using this data structure is it avoids having
446 * to reparse the possibly discontiguous S/G list in the original
447 * request. Due to the way that the mapping of the memory backing an
448 * I/O transaction is handled by Xen, a second pass is unavoidable.
449 * At least this way the second walk is a simple array traversal.
451 * \note A single Scatter/Gather element in the block interface covers
452 * at most 1 machine page. In this context a sector (blkif
453 * nomenclature, not what I'd choose) is a 512b aligned unit
454 * of mapping within the machine page referenced by an S/G
458 /** The number of 512b data chunks mapped in this S/G element. */
462 * The index (0 based) of the first 512b data chunk mapped
463 * in this S/G element.
468 * The index (0 based) of the last 512b data chunk mapped
469 * in this S/G element.
475 * Character device backend specific configuration data.
477 struct xbb_dev_data {
478 /** Cdev used for device backend access. */
481 /** Cdev switch used for device backend access. */
484 /** Used to hold a reference on opened cdev backend devices. */
489 * File backend specific configuration data.
491 struct xbb_file_data {
492 /** Credentials to use for vnode backed (file based) I/O. */
496 * \brief Array of io vectors used to process file based I/O.
498 * Only a single file based request is outstanding per-xbb instance,
499 * so we only need one of these.
501 struct iovec xiovecs[XBB_MAX_SEGMENTS_PER_REQLIST];
502 #ifdef XBB_USE_BOUNCE_BUFFERS
505 * \brief Array of io vectors used to handle bouncing of file reads.
507 * Vnode operations are free to modify uio data during their
508 * exectuion. In the case of a read with bounce buffering active,
509 * we need some of the data from the original uio in order to
510 * bounce-out the read data. This array serves as the temporary
511 * storage for this saved data.
513 struct iovec saved_xiovecs[XBB_MAX_SEGMENTS_PER_REQLIST];
516 * \brief Array of memoized bounce buffer kva offsets used
517 * in the file based backend.
519 * Due to the way that the mapping of the memory backing an
520 * I/O transaction is handled by Xen, a second pass through
521 * the request sg elements is unavoidable. We memoize the computed
522 * bounce address here to reduce the cost of the second walk.
524 void *xiovecs_vaddr[XBB_MAX_SEGMENTS_PER_REQLIST];
525 #endif /* XBB_USE_BOUNCE_BUFFERS */
529 * Collection of backend type specific data.
531 union xbb_backend_data {
532 struct xbb_dev_data dev;
533 struct xbb_file_data file;
537 * Function signature of backend specific I/O handlers.
539 typedef int (*xbb_dispatch_t)(struct xbb_softc *xbb,
540 struct xbb_xen_reqlist *reqlist, int operation,
544 * Per-instance configuration data.
549 * Task-queue used to process I/O requests.
551 struct taskqueue *io_taskqueue;
554 * Single "run the request queue" task enqueued
559 /** Device type for this instance. */
560 xbb_type device_type;
562 /** NewBus device corresponding to this instance. */
565 /** Backend specific dispatch routine for this instance. */
566 xbb_dispatch_t dispatch_io;
568 /** The number of requests outstanding on the backend device/file. */
569 int active_request_count;
571 /** Free pool of request tracking structures. */
572 struct xbb_xen_req_list request_free_stailq;
574 /** Array, sized at connection time, of request tracking structures. */
575 struct xbb_xen_req *requests;
577 /** Free pool of request list structures. */
578 struct xbb_xen_reqlist_list reqlist_free_stailq;
580 /** List of pending request lists awaiting execution. */
581 struct xbb_xen_reqlist_list reqlist_pending_stailq;
583 /** Array, sized at connection time, of request list structures. */
584 struct xbb_xen_reqlist *request_lists;
587 * Global pool of kva used for mapping remote domain ring
588 * and I/O transaction data.
592 /** Psuedo-physical address corresponding to kva. */
593 uint64_t gnt_base_addr;
595 /** The size of the global kva pool. */
598 /** The size of the KVA area used for request lists. */
599 int reqlist_kva_size;
601 /** The number of pages of KVA used for request lists */
602 int reqlist_kva_pages;
604 /** Bitmap of free KVA pages */
608 * \brief Cached value of the front-end's domain id.
610 * This value is used at once for each mapped page in
611 * a transaction. We cache it to avoid incuring the
612 * cost of an ivar access every time this is needed.
617 * \brief The blkif protocol abi in effect.
619 * There are situations where the back and front ends can
620 * have a different, native abi (e.g. intel x86_64 and
621 * 32bit x86 domains on the same machine). The back-end
622 * always accomodates the front-end's native abi. That
623 * value is pulled from the XenStore and recorded here.
628 * \brief The maximum number of requests and request lists allowed
629 * to be in flight at a time.
631 * This value is negotiated via the XenStore.
636 * \brief The maximum number of segments (1 page per segment)
637 * that can be mapped by a request.
639 * This value is negotiated via the XenStore.
641 u_int max_request_segments;
644 * \brief Maximum number of segments per request list.
646 * This value is derived from and will generally be larger than
647 * max_request_segments.
649 u_int max_reqlist_segments;
652 * The maximum size of any request to this back-end
655 * This value is negotiated via the XenStore.
657 u_int max_request_size;
660 * The maximum size of any request list. This is derived directly
661 * from max_reqlist_segments.
663 u_int max_reqlist_size;
665 /** Various configuration and state bit flags. */
668 /** Ring mapping and interrupt configuration data. */
669 struct xbb_ring_config ring_config;
671 /** Runtime, cross-abi safe, structures for ring access. */
672 blkif_back_rings_t rings;
674 /** IRQ mapping for the communication ring event channel. */
675 xen_intr_handle_t xen_intr_handle;
678 * \brief Backend access mode flags (e.g. write, or read-only).
680 * This value is passed to us by the front-end via the XenStore.
685 * \brief Backend device type (e.g. "disk", "cdrom", "floppy").
687 * This value is passed to us by the front-end via the XenStore.
693 * \brief Backend device/file identifier.
695 * This value is passed to us by the front-end via the XenStore.
696 * We expect this to be a POSIX path indicating the file or
702 * Vnode corresponding to the backend device node or file
707 union xbb_backend_data backend;
709 /** The native sector size of the backend. */
712 /** log2 of sector_size. */
713 u_int sector_size_shift;
715 /** Size in bytes of the backend device or file. */
719 * \brief media_size expressed in terms of the backend native
722 * (e.g. xbb->media_size >> xbb->sector_size_shift).
724 uint64_t media_num_sectors;
727 * \brief Array of memoized scatter gather data computed during the
728 * conversion of blkif ring requests to internal xbb_xen_req
731 * Ring processing is serialized so we only need one of these.
733 struct xbb_sg xbb_sgs[XBB_MAX_SEGMENTS_PER_REQLIST];
736 * Temporary grant table map used in xbb_dispatch_io(). When
737 * XBB_MAX_SEGMENTS_PER_REQLIST gets large, keeping this on the
738 * stack could cause a stack overflow.
740 struct gnttab_map_grant_ref maps[XBB_MAX_SEGMENTS_PER_REQLIST];
742 /** Mutex protecting per-instance data. */
747 * Resource representing allocated physical address space
748 * associated with our per-instance kva region.
750 struct resource *pseudo_phys_res;
752 /** Resource id for allocated physical address space. */
753 int pseudo_phys_res_id;
757 * I/O statistics from BlockBack dispatch down. These are
758 * coalesced requests, and we start them right before execution.
760 struct devstat *xbb_stats;
763 * I/O statistics coming into BlockBack. These are the requests as
764 * we get them from BlockFront. They are started as soon as we
765 * receive a request, and completed when the I/O is complete.
767 struct devstat *xbb_stats_in;
769 /** Disable sending flush to the backend */
772 /** Send a real flush for every N flush requests */
775 /** Count of flush requests in the interval */
778 /** Don't coalesce requests if this is set */
779 int no_coalesce_reqs;
781 /** Number of requests we have received */
782 uint64_t reqs_received;
784 /** Number of requests we have completed*/
785 uint64_t reqs_completed;
787 /** Number of requests we queued but not pushed*/
788 uint64_t reqs_queued_for_completion;
790 /** Number of requests we completed with an error status*/
791 uint64_t reqs_completed_with_error;
793 /** How many forced dispatches (i.e. without coalescing) have happend */
794 uint64_t forced_dispatch;
796 /** How many normal dispatches have happend */
797 uint64_t normal_dispatch;
799 /** How many total dispatches have happend */
800 uint64_t total_dispatch;
802 /** How many times we have run out of KVA */
803 uint64_t kva_shortages;
805 /** How many times we have run out of request structures */
806 uint64_t request_shortages;
809 /*---------------------------- Request Processing ----------------------------*/
811 * Allocate an internal transaction tracking structure from the free pool.
813 * \param xbb Per-instance xbb configuration structure.
815 * \return On success, a pointer to the allocated xbb_xen_req structure.
818 static inline struct xbb_xen_req *
819 xbb_get_req(struct xbb_softc *xbb)
821 struct xbb_xen_req *req;
825 mtx_assert(&xbb->lock, MA_OWNED);
827 if ((req = STAILQ_FIRST(&xbb->request_free_stailq)) != NULL) {
828 STAILQ_REMOVE_HEAD(&xbb->request_free_stailq, links);
829 xbb->active_request_count++;
836 * Return an allocated transaction tracking structure to the free pool.
838 * \param xbb Per-instance xbb configuration structure.
839 * \param req The request structure to free.
842 xbb_release_req(struct xbb_softc *xbb, struct xbb_xen_req *req)
844 mtx_assert(&xbb->lock, MA_OWNED);
846 STAILQ_INSERT_HEAD(&xbb->request_free_stailq, req, links);
847 xbb->active_request_count--;
849 KASSERT(xbb->active_request_count >= 0,
850 ("xbb_release_req: negative active count"));
854 * Return an xbb_xen_req_list of allocated xbb_xen_reqs to the free pool.
856 * \param xbb Per-instance xbb configuration structure.
857 * \param req_list The list of requests to free.
858 * \param nreqs The number of items in the list.
861 xbb_release_reqs(struct xbb_softc *xbb, struct xbb_xen_req_list *req_list,
864 mtx_assert(&xbb->lock, MA_OWNED);
866 STAILQ_CONCAT(&xbb->request_free_stailq, req_list);
867 xbb->active_request_count -= nreqs;
869 KASSERT(xbb->active_request_count >= 0,
870 ("xbb_release_reqs: negative active count"));
874 * Given a page index and 512b sector offset within that page,
875 * calculate an offset into a request's kva region.
877 * \param reqlist The request structure whose kva region will be accessed.
878 * \param pagenr The page index used to compute the kva offset.
879 * \param sector The 512b sector index used to compute the page relative
882 * \return The computed global KVA offset.
884 static inline uint8_t *
885 xbb_reqlist_vaddr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector)
887 return (reqlist->kva + (PAGE_SIZE * pagenr) + (sector << 9));
890 #ifdef XBB_USE_BOUNCE_BUFFERS
892 * Given a page index and 512b sector offset within that page,
893 * calculate an offset into a request's local bounce memory region.
895 * \param reqlist The request structure whose bounce region will be accessed.
896 * \param pagenr The page index used to compute the bounce offset.
897 * \param sector The 512b sector index used to compute the page relative
900 * \return The computed global bounce buffer address.
902 static inline uint8_t *
903 xbb_reqlist_bounce_addr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector)
905 return (reqlist->bounce + (PAGE_SIZE * pagenr) + (sector << 9));
910 * Given a page number and 512b sector offset within that page,
911 * calculate an offset into the request's memory region that the
912 * underlying backend device/file should use for I/O.
914 * \param reqlist The request structure whose I/O region will be accessed.
915 * \param pagenr The page index used to compute the I/O offset.
916 * \param sector The 512b sector index used to compute the page relative
919 * \return The computed global I/O address.
921 * Depending on configuration, this will either be a local bounce buffer
922 * or a pointer to the memory mapped in from the front-end domain for
925 static inline uint8_t *
926 xbb_reqlist_ioaddr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector)
928 #ifdef XBB_USE_BOUNCE_BUFFERS
929 return (xbb_reqlist_bounce_addr(reqlist, pagenr, sector));
931 return (xbb_reqlist_vaddr(reqlist, pagenr, sector));
936 * Given a page index and 512b sector offset within that page, calculate
937 * an offset into the local psuedo-physical address space used to map a
938 * front-end's request data into a request.
940 * \param reqlist The request list structure whose pseudo-physical region
942 * \param pagenr The page index used to compute the pseudo-physical offset.
943 * \param sector The 512b sector index used to compute the page relative
944 * pseudo-physical offset.
946 * \return The computed global pseudo-phsyical address.
948 * Depending on configuration, this will either be a local bounce buffer
949 * or a pointer to the memory mapped in from the front-end domain for
952 static inline uintptr_t
953 xbb_get_gntaddr(struct xbb_xen_reqlist *reqlist, int pagenr, int sector)
955 struct xbb_softc *xbb;
959 return ((uintptr_t)(xbb->gnt_base_addr +
960 (uintptr_t)(reqlist->kva - xbb->kva) +
961 (PAGE_SIZE * pagenr) + (sector << 9)));
965 * Get Kernel Virtual Address space for mapping requests.
967 * \param xbb Per-instance xbb configuration structure.
968 * \param nr_pages Number of pages needed.
969 * \param check_only If set, check for free KVA but don't allocate it.
970 * \param have_lock If set, xbb lock is already held.
972 * \return On success, a pointer to the allocated KVA region. Otherwise NULL.
974 * Note: This should be unnecessary once we have either chaining or
975 * scatter/gather support for struct bio. At that point we'll be able to
976 * put multiple addresses and lengths in one bio/bio chain and won't need
977 * to map everything into one virtual segment.
980 xbb_get_kva(struct xbb_softc *xbb, int nr_pages)
982 intptr_t first_clear;
987 KASSERT(nr_pages != 0, ("xbb_get_kva of zero length"));
992 mtx_lock(&xbb->lock);
995 * Look for the first available page. If there are none, we're done.
997 bit_ffc(xbb->kva_free, xbb->reqlist_kva_pages, &first_clear);
999 if (first_clear == -1)
1003 * Starting at the first available page, look for consecutive free
1004 * pages that will satisfy the user's request.
1006 for (i = first_clear, num_clear = 0; i < xbb->reqlist_kva_pages; i++) {
1008 * If this is true, the page is used, so we have to reset
1009 * the number of clear pages and the first clear page
1010 * (since it pointed to a region with an insufficient number
1013 if (bit_test(xbb->kva_free, i)) {
1019 if (first_clear == -1)
1023 * If this is true, we've found a large enough free region
1024 * to satisfy the request.
1026 if (++num_clear == nr_pages) {
1028 bit_nset(xbb->kva_free, first_clear,
1029 first_clear + nr_pages - 1);
1031 free_kva = xbb->kva +
1032 (uint8_t *)(first_clear * PAGE_SIZE);
1034 KASSERT(free_kva >= (uint8_t *)xbb->kva &&
1035 free_kva + (nr_pages * PAGE_SIZE) <=
1036 (uint8_t *)xbb->ring_config.va,
1037 ("Free KVA %p len %d out of range, "
1038 "kva = %#jx, ring VA = %#jx\n", free_kva,
1039 nr_pages * PAGE_SIZE, (uintmax_t)xbb->kva,
1040 (uintmax_t)xbb->ring_config.va));
1047 if (free_kva == NULL) {
1048 xbb->flags |= XBBF_RESOURCE_SHORTAGE;
1049 xbb->kva_shortages++;
1052 mtx_unlock(&xbb->lock);
1058 * Free allocated KVA.
1060 * \param xbb Per-instance xbb configuration structure.
1061 * \param kva_ptr Pointer to allocated KVA region.
1062 * \param nr_pages Number of pages in the KVA region.
1065 xbb_free_kva(struct xbb_softc *xbb, uint8_t *kva_ptr, int nr_pages)
1067 intptr_t start_page;
1069 mtx_assert(&xbb->lock, MA_OWNED);
1071 start_page = (intptr_t)(kva_ptr - xbb->kva) >> PAGE_SHIFT;
1072 bit_nclear(xbb->kva_free, start_page, start_page + nr_pages - 1);
1077 * Unmap the front-end pages associated with this I/O request.
1079 * \param req The request structure to unmap.
1082 xbb_unmap_reqlist(struct xbb_xen_reqlist *reqlist)
1084 struct gnttab_unmap_grant_ref unmap[XBB_MAX_SEGMENTS_PER_REQLIST];
1090 for (i = 0; i < reqlist->nr_segments; i++) {
1092 if (reqlist->gnt_handles[i] == GRANT_REF_INVALID)
1095 unmap[invcount].host_addr = xbb_get_gntaddr(reqlist, i, 0);
1096 unmap[invcount].dev_bus_addr = 0;
1097 unmap[invcount].handle = reqlist->gnt_handles[i];
1098 reqlist->gnt_handles[i] = GRANT_REF_INVALID;
1102 error = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
1104 KASSERT(error == 0, ("Grant table operation failed"));
1108 * Allocate an internal transaction tracking structure from the free pool.
1110 * \param xbb Per-instance xbb configuration structure.
1112 * \return On success, a pointer to the allocated xbb_xen_reqlist structure.
1115 static inline struct xbb_xen_reqlist *
1116 xbb_get_reqlist(struct xbb_softc *xbb)
1118 struct xbb_xen_reqlist *reqlist;
1122 mtx_assert(&xbb->lock, MA_OWNED);
1124 if ((reqlist = STAILQ_FIRST(&xbb->reqlist_free_stailq)) != NULL) {
1126 STAILQ_REMOVE_HEAD(&xbb->reqlist_free_stailq, links);
1127 reqlist->flags = XBB_REQLIST_NONE;
1128 reqlist->kva = NULL;
1129 reqlist->status = BLKIF_RSP_OKAY;
1130 reqlist->residual_512b_sectors = 0;
1131 reqlist->num_children = 0;
1132 reqlist->nr_segments = 0;
1133 STAILQ_INIT(&reqlist->contig_req_list);
1140 * Return an allocated transaction tracking structure to the free pool.
1142 * \param xbb Per-instance xbb configuration structure.
1143 * \param req The request list structure to free.
1144 * \param wakeup If set, wakeup the work thread if freeing this reqlist
1145 * during a resource shortage condition.
1148 xbb_release_reqlist(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist,
1152 mtx_assert(&xbb->lock, MA_OWNED);
1155 wakeup = xbb->flags & XBBF_RESOURCE_SHORTAGE;
1156 xbb->flags &= ~XBBF_RESOURCE_SHORTAGE;
1159 if (reqlist->kva != NULL)
1160 xbb_free_kva(xbb, reqlist->kva, reqlist->nr_segments);
1162 xbb_release_reqs(xbb, &reqlist->contig_req_list, reqlist->num_children);
1164 STAILQ_INSERT_TAIL(&xbb->reqlist_free_stailq, reqlist, links);
1166 if ((xbb->flags & XBBF_SHUTDOWN) != 0) {
1168 * Shutdown is in progress. See if we can
1169 * progress further now that one more request
1170 * has completed and been returned to the
1177 taskqueue_enqueue(xbb->io_taskqueue, &xbb->io_task);
1181 * Request resources and do basic request setup.
1183 * \param xbb Per-instance xbb configuration structure.
1184 * \param reqlist Pointer to reqlist pointer.
1185 * \param ring_req Pointer to a block ring request.
1186 * \param ring_index The ring index of this request.
1188 * \return 0 for success, non-zero for failure.
1191 xbb_get_resources(struct xbb_softc *xbb, struct xbb_xen_reqlist **reqlist,
1192 blkif_request_t *ring_req, RING_IDX ring_idx)
1194 struct xbb_xen_reqlist *nreqlist;
1195 struct xbb_xen_req *nreq;
1200 mtx_lock(&xbb->lock);
1203 * We don't allow new resources to be allocated if we're in the
1204 * process of shutting down.
1206 if ((xbb->flags & XBBF_SHUTDOWN) != 0) {
1207 mtx_unlock(&xbb->lock);
1212 * Allocate a reqlist if the caller doesn't have one already.
1214 if (*reqlist == NULL) {
1215 nreqlist = xbb_get_reqlist(xbb);
1216 if (nreqlist == NULL)
1220 /* We always allocate a request. */
1221 nreq = xbb_get_req(xbb);
1225 mtx_unlock(&xbb->lock);
1227 if (*reqlist == NULL) {
1228 *reqlist = nreqlist;
1229 nreqlist->operation = ring_req->operation;
1230 nreqlist->starting_sector_number = ring_req->sector_number;
1231 STAILQ_INSERT_TAIL(&xbb->reqlist_pending_stailq, nreqlist,
1235 nreq->reqlist = *reqlist;
1236 nreq->req_ring_idx = ring_idx;
1237 nreq->id = ring_req->id;
1238 nreq->operation = ring_req->operation;
1240 if (xbb->abi != BLKIF_PROTOCOL_NATIVE) {
1241 bcopy(ring_req, &nreq->ring_req_storage, sizeof(*ring_req));
1242 nreq->ring_req = &nreq->ring_req_storage;
1244 nreq->ring_req = ring_req;
1247 binuptime(&nreq->ds_t0);
1248 devstat_start_transaction(xbb->xbb_stats_in, &nreq->ds_t0);
1249 STAILQ_INSERT_TAIL(&(*reqlist)->contig_req_list, nreq, links);
1250 (*reqlist)->num_children++;
1251 (*reqlist)->nr_segments += ring_req->nr_segments;
1258 * We're out of resources, so set the shortage flag. The next time
1259 * a request is released, we'll try waking up the work thread to
1260 * see if we can allocate more resources.
1262 xbb->flags |= XBBF_RESOURCE_SHORTAGE;
1263 xbb->request_shortages++;
1266 xbb_release_req(xbb, nreq);
1268 if (nreqlist != NULL)
1269 xbb_release_reqlist(xbb, nreqlist, /*wakeup*/ 0);
1271 mtx_unlock(&xbb->lock);
1277 * Create and queue a response to a blkif request.
1279 * \param xbb Per-instance xbb configuration structure.
1280 * \param req The request structure to which to respond.
1281 * \param status The status code to report. See BLKIF_RSP_*
1282 * in sys/xen/interface/io/blkif.h.
1285 xbb_queue_response(struct xbb_softc *xbb, struct xbb_xen_req *req, int status)
1287 blkif_response_t *resp;
1290 * The mutex is required here, and should be held across this call
1291 * until after the subsequent call to xbb_push_responses(). This
1292 * is to guarantee that another context won't queue responses and
1293 * push them while we're active.
1295 * That could lead to the other end being notified of responses
1296 * before the resources have been freed on this end. The other end
1297 * would then be able to queue additional I/O, and we may run out
1298 * of resources because we haven't freed them all yet.
1300 mtx_assert(&xbb->lock, MA_OWNED);
1303 * Place on the response ring for the relevant domain.
1304 * For now, only the spacing between entries is different
1305 * in the different ABIs, not the response entry layout.
1308 case BLKIF_PROTOCOL_NATIVE:
1309 resp = RING_GET_RESPONSE(&xbb->rings.native,
1310 xbb->rings.native.rsp_prod_pvt);
1312 case BLKIF_PROTOCOL_X86_32:
1313 resp = (blkif_response_t *)
1314 RING_GET_RESPONSE(&xbb->rings.x86_32,
1315 xbb->rings.x86_32.rsp_prod_pvt);
1317 case BLKIF_PROTOCOL_X86_64:
1318 resp = (blkif_response_t *)
1319 RING_GET_RESPONSE(&xbb->rings.x86_64,
1320 xbb->rings.x86_64.rsp_prod_pvt);
1323 panic("Unexpected blkif protocol ABI.");
1327 resp->operation = req->operation;
1328 resp->status = status;
1330 if (status != BLKIF_RSP_OKAY)
1331 xbb->reqs_completed_with_error++;
1333 xbb->rings.common.rsp_prod_pvt += BLKIF_SEGS_TO_BLOCKS(req->nr_pages);
1335 xbb->reqs_queued_for_completion++;
1340 * Send queued responses to blkif requests.
1342 * \param xbb Per-instance xbb configuration structure.
1343 * \param run_taskqueue Flag that is set to 1 if the taskqueue
1344 * should be run, 0 if it does not need to be run.
1345 * \param notify Flag that is set to 1 if the other end should be
1346 * notified via irq, 0 if the other end should not be
1350 xbb_push_responses(struct xbb_softc *xbb, int *run_taskqueue, int *notify)
1355 * The mutex is required here.
1357 mtx_assert(&xbb->lock, MA_OWNED);
1361 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&xbb->rings.common, *notify);
1363 if (xbb->rings.common.rsp_prod_pvt == xbb->rings.common.req_cons) {
1366 * Tail check for pending requests. Allows frontend to avoid
1367 * notifications if requests are already in flight (lower
1368 * overheads and promotes batching).
1370 RING_FINAL_CHECK_FOR_REQUESTS(&xbb->rings.common, more_to_do);
1371 } else if (RING_HAS_UNCONSUMED_REQUESTS(&xbb->rings.common)) {
1376 xbb->reqs_completed += xbb->reqs_queued_for_completion;
1377 xbb->reqs_queued_for_completion = 0;
1379 *run_taskqueue = more_to_do;
1383 * Complete a request list.
1385 * \param xbb Per-instance xbb configuration structure.
1386 * \param reqlist Allocated internal request list structure.
1389 xbb_complete_reqlist(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist)
1391 struct xbb_xen_req *nreq;
1393 int notify, run_taskqueue;
1397 if (reqlist->flags & XBB_REQLIST_MAPPED)
1398 xbb_unmap_reqlist(reqlist);
1400 mtx_lock(&xbb->lock);
1403 * All I/O is done, send the response. A lock is not necessary
1404 * to protect the request list, because all requests have
1405 * completed. Therefore this is the only context accessing this
1406 * reqlist right now. However, in order to make sure that no one
1407 * else queues responses onto the queue or pushes them to the other
1408 * side while we're active, we need to hold the lock across the
1409 * calls to xbb_queue_response() and xbb_push_responses().
1411 STAILQ_FOREACH(nreq, &reqlist->contig_req_list, links) {
1412 off_t cur_sectors_sent;
1414 /* Put this response on the ring, but don't push yet */
1415 xbb_queue_response(xbb, nreq, reqlist->status);
1417 /* We don't report bytes sent if there is an error. */
1418 if (reqlist->status == BLKIF_RSP_OKAY)
1419 cur_sectors_sent = nreq->nr_512b_sectors;
1421 cur_sectors_sent = 0;
1423 sectors_sent += cur_sectors_sent;
1425 devstat_end_transaction(xbb->xbb_stats_in,
1426 /*bytes*/cur_sectors_sent << 9,
1427 reqlist->ds_tag_type,
1428 reqlist->ds_trans_type,
1430 /*then*/&nreq->ds_t0);
1434 * Take out any sectors not sent. If we wind up negative (which
1435 * might happen if an error is reported as well as a residual), just
1436 * report 0 sectors sent.
1438 sectors_sent -= reqlist->residual_512b_sectors;
1439 if (sectors_sent < 0)
1442 devstat_end_transaction(xbb->xbb_stats,
1443 /*bytes*/ sectors_sent << 9,
1444 reqlist->ds_tag_type,
1445 reqlist->ds_trans_type,
1447 /*then*/&reqlist->ds_t0);
1449 xbb_release_reqlist(xbb, reqlist, /*wakeup*/ 1);
1451 xbb_push_responses(xbb, &run_taskqueue, ¬ify);
1453 mtx_unlock(&xbb->lock);
1456 taskqueue_enqueue(xbb->io_taskqueue, &xbb->io_task);
1459 xen_intr_signal(xbb->xen_intr_handle);
1463 * Completion handler for buffer I/O requests issued by the device
1466 * \param bio The buffer I/O request on which to perform completion
1470 xbb_bio_done(struct bio *bio)
1472 struct xbb_softc *xbb;
1473 struct xbb_xen_reqlist *reqlist;
1475 reqlist = bio->bio_caller1;
1478 reqlist->residual_512b_sectors += bio->bio_resid >> 9;
1481 * This is a bit imprecise. With aggregated I/O a single
1482 * request list can contain multiple front-end requests and
1483 * a multiple bios may point to a single request. By carefully
1484 * walking the request list, we could map residuals and errors
1485 * back to the original front-end request, but the interface
1486 * isn't sufficiently rich for us to properly report the error.
1487 * So, we just treat the entire request list as having failed if an
1488 * error occurs on any part. And, if an error occurs, we treat
1489 * the amount of data transferred as 0.
1491 * For residuals, we report it on the overall aggregated device,
1492 * but not on the individual requests, since we don't currently
1493 * do the work to determine which front-end request to which the
1496 if (bio->bio_error) {
1497 DPRINTF("BIO returned error %d for operation on device %s\n",
1498 bio->bio_error, xbb->dev_name);
1499 reqlist->status = BLKIF_RSP_ERROR;
1501 if (bio->bio_error == ENXIO
1502 && xenbus_get_state(xbb->dev) == XenbusStateConnected) {
1505 * Backend device has disappeared. Signal the
1506 * front-end that we (the device proxy) want to
1509 xenbus_set_state(xbb->dev, XenbusStateClosing);
1513 #ifdef XBB_USE_BOUNCE_BUFFERS
1514 if (bio->bio_cmd == BIO_READ) {
1515 vm_offset_t kva_offset;
1517 kva_offset = (vm_offset_t)bio->bio_data
1518 - (vm_offset_t)reqlist->bounce;
1519 memcpy((uint8_t *)reqlist->kva + kva_offset,
1520 bio->bio_data, bio->bio_bcount);
1522 #endif /* XBB_USE_BOUNCE_BUFFERS */
1525 * Decrement the pending count for the request list. When we're
1526 * done with the requests, send status back for all of them.
1528 if (atomic_fetchadd_int(&reqlist->pendcnt, -1) == 1)
1529 xbb_complete_reqlist(xbb, reqlist);
1535 * Parse a blkif request into an internal request structure and send
1536 * it to the backend for processing.
1538 * \param xbb Per-instance xbb configuration structure.
1539 * \param reqlist Allocated internal request list structure.
1541 * \return On success, 0. For resource shortages, non-zero.
1543 * This routine performs the backend common aspects of request parsing
1544 * including compiling an internal request structure, parsing the S/G
1545 * list and any secondary ring requests in which they may reside, and
1546 * the mapping of front-end I/O pages into our domain.
1549 xbb_dispatch_io(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist)
1551 struct xbb_sg *xbb_sg;
1552 struct gnttab_map_grant_ref *map;
1553 struct blkif_request_segment *sg;
1554 struct blkif_request_segment *last_block_sg;
1555 struct xbb_xen_req *nreq;
1565 reqlist->ds_tag_type = DEVSTAT_TAG_SIMPLE;
1571 * First determine whether we have enough free KVA to satisfy this
1572 * request list. If not, tell xbb_run_queue() so it can go to
1573 * sleep until we have more KVA.
1575 reqlist->kva = NULL;
1576 if (reqlist->nr_segments != 0) {
1577 reqlist->kva = xbb_get_kva(xbb, reqlist->nr_segments);
1578 if (reqlist->kva == NULL) {
1580 * If we're out of KVA, return ENOMEM.
1586 binuptime(&reqlist->ds_t0);
1587 devstat_start_transaction(xbb->xbb_stats, &reqlist->ds_t0);
1589 switch (reqlist->operation) {
1590 case BLKIF_OP_WRITE_BARRIER:
1591 bio_flags |= BIO_ORDERED;
1592 reqlist->ds_tag_type = DEVSTAT_TAG_ORDERED;
1594 case BLKIF_OP_WRITE:
1595 operation = BIO_WRITE;
1596 reqlist->ds_trans_type = DEVSTAT_WRITE;
1597 if ((xbb->flags & XBBF_READ_ONLY) != 0) {
1598 DPRINTF("Attempt to write to read only device %s\n",
1600 reqlist->status = BLKIF_RSP_ERROR;
1605 operation = BIO_READ;
1606 reqlist->ds_trans_type = DEVSTAT_READ;
1608 case BLKIF_OP_FLUSH_DISKCACHE:
1610 * If this is true, the user has requested that we disable
1611 * flush support. So we just complete the requests
1614 if (xbb->disable_flush != 0) {
1619 * The user has requested that we only send a real flush
1620 * for every N flush requests. So keep count, and either
1621 * complete the request immediately or queue it for the
1624 if (xbb->flush_interval != 0) {
1625 if (++(xbb->flush_count) < xbb->flush_interval) {
1628 xbb->flush_count = 0;
1631 operation = BIO_FLUSH;
1632 reqlist->ds_tag_type = DEVSTAT_TAG_ORDERED;
1633 reqlist->ds_trans_type = DEVSTAT_NO_DATA;
1637 DPRINTF("error: unknown block io operation [%d]\n",
1638 reqlist->operation);
1639 reqlist->status = BLKIF_RSP_ERROR;
1644 xbb_sg = xbb->xbb_sgs;
1648 STAILQ_FOREACH(nreq, &reqlist->contig_req_list, links) {
1649 blkif_request_t *ring_req;
1650 RING_IDX req_ring_idx;
1653 ring_req = nreq->ring_req;
1654 req_ring_idx = nreq->req_ring_idx;
1656 nseg = ring_req->nr_segments;
1657 nreq->nr_pages = nseg;
1658 nreq->nr_512b_sectors = 0;
1662 /* Check that number of segments is sane. */
1663 if (__predict_false(nseg == 0)
1664 || __predict_false(nseg > xbb->max_request_segments)) {
1665 DPRINTF("Bad number of segments in request (%d)\n",
1667 reqlist->status = BLKIF_RSP_ERROR;
1671 block_segs = MIN(nreq->nr_pages,
1672 BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK);
1674 last_block_sg = sg + block_segs;
1677 while (sg < last_block_sg) {
1679 XBB_MAX_SEGMENTS_PER_REQLIST,
1680 ("seg_idx %d is too large, max "
1681 "segs %d\n", seg_idx,
1682 XBB_MAX_SEGMENTS_PER_REQLIST));
1684 xbb_sg->first_sect = sg->first_sect;
1685 xbb_sg->last_sect = sg->last_sect;
1687 (int8_t)(sg->last_sect -
1688 sg->first_sect + 1);
1690 if ((sg->last_sect >= (PAGE_SIZE >> 9))
1691 || (xbb_sg->nsect <= 0)) {
1692 reqlist->status = BLKIF_RSP_ERROR;
1696 nr_sects += xbb_sg->nsect;
1697 map->host_addr = xbb_get_gntaddr(reqlist,
1698 seg_idx, /*sector*/0);
1699 KASSERT(map->host_addr + PAGE_SIZE <=
1700 xbb->ring_config.gnt_addr,
1701 ("Host address %#jx len %d overlaps "
1702 "ring address %#jx\n",
1703 (uintmax_t)map->host_addr, PAGE_SIZE,
1704 (uintmax_t)xbb->ring_config.gnt_addr));
1706 map->flags = GNTMAP_host_map;
1707 map->ref = sg->gref;
1708 map->dom = xbb->otherend_id;
1709 if (operation == BIO_WRITE)
1710 map->flags |= GNTMAP_readonly;
1718 block_segs = MIN(nseg - req_seg_idx,
1719 BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK);
1720 if (block_segs == 0)
1724 * Fetch the next request block full of SG elements.
1725 * For now, only the spacing between entries is
1726 * different in the different ABIs, not the sg entry
1731 case BLKIF_PROTOCOL_NATIVE:
1732 sg = BLKRING_GET_SEG_BLOCK(&xbb->rings.native,
1735 case BLKIF_PROTOCOL_X86_32:
1737 sg = BLKRING_GET_SEG_BLOCK(&xbb->rings.x86_32,
1741 case BLKIF_PROTOCOL_X86_64:
1743 sg = BLKRING_GET_SEG_BLOCK(&xbb->rings.x86_64,
1748 panic("Unexpected blkif protocol ABI.");
1751 last_block_sg = sg + block_segs;
1754 /* Convert to the disk's sector size */
1755 nreq->nr_512b_sectors = nr_sects;
1756 nr_sects = (nr_sects << 9) >> xbb->sector_size_shift;
1757 total_sects += nr_sects;
1759 if ((nreq->nr_512b_sectors &
1760 ((xbb->sector_size >> 9) - 1)) != 0) {
1761 device_printf(xbb->dev, "%s: I/O size (%d) is not "
1762 "a multiple of the backing store sector "
1763 "size (%d)\n", __func__,
1764 nreq->nr_512b_sectors << 9,
1766 reqlist->status = BLKIF_RSP_ERROR;
1771 error = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
1772 xbb->maps, reqlist->nr_segments);
1774 panic("Grant table operation failed (%d)", error);
1776 reqlist->flags |= XBB_REQLIST_MAPPED;
1778 for (seg_idx = 0, map = xbb->maps; seg_idx < reqlist->nr_segments;
1781 if (__predict_false(map->status != 0)) {
1782 DPRINTF("invalid buffer -- could not remap "
1783 "it (%d)\n", map->status);
1784 DPRINTF("Mapping(%d): Host Addr 0x%lx, flags "
1785 "0x%x ref 0x%x, dom %d\n", seg_idx,
1786 map->host_addr, map->flags, map->ref,
1788 reqlist->status = BLKIF_RSP_ERROR;
1792 reqlist->gnt_handles[seg_idx] = map->handle;
1794 if (reqlist->starting_sector_number + total_sects >
1795 xbb->media_num_sectors) {
1797 DPRINTF("%s of [%" PRIu64 ",%" PRIu64 "] "
1798 "extends past end of device %s\n",
1799 operation == BIO_READ ? "read" : "write",
1800 reqlist->starting_sector_number,
1801 reqlist->starting_sector_number + total_sects,
1803 reqlist->status = BLKIF_RSP_ERROR;
1809 error = xbb->dispatch_io(xbb,
1815 reqlist->status = BLKIF_RSP_ERROR;
1823 xbb_complete_reqlist(xbb, reqlist);
1829 xbb_count_sects(blkif_request_t *ring_req)
1834 for (i = 0; i < ring_req->nr_segments; i++) {
1837 nsect = (int8_t)(ring_req->seg[i].last_sect -
1838 ring_req->seg[i].first_sect + 1);
1849 * Process incoming requests from the shared communication ring in response
1850 * to a signal on the ring's event channel.
1852 * \param context Callback argument registerd during task initialization -
1853 * the xbb_softc for this instance.
1854 * \param pending The number of taskqueue_enqueue events that have
1855 * occurred since this handler was last run.
1858 xbb_run_queue(void *context, int pending)
1860 struct xbb_softc *xbb;
1861 blkif_back_rings_t *rings;
1863 uint64_t cur_sector;
1865 struct xbb_xen_reqlist *reqlist;
1868 xbb = (struct xbb_softc *)context;
1869 rings = &xbb->rings;
1872 * Work gather and dispatch loop. Note that we have a bias here
1873 * towards gathering I/O sent by blockfront. We first gather up
1874 * everything in the ring, as long as we have resources. Then we
1875 * dispatch one request, and then attempt to gather up any
1876 * additional requests that have come in while we were dispatching
1879 * This allows us to get a clearer picture (via devstat) of how
1880 * many requests blockfront is queueing to us at any given time.
1886 * Initialize reqlist to the last element in the pending
1887 * queue, if there is one. This allows us to add more
1888 * requests to that request list, if we have room.
1890 reqlist = STAILQ_LAST(&xbb->reqlist_pending_stailq,
1891 xbb_xen_reqlist, links);
1892 if (reqlist != NULL) {
1893 cur_sector = reqlist->next_contig_sector;
1894 cur_operation = reqlist->operation;
1901 * Cache req_prod to avoid accessing a cache line shared
1902 * with the frontend.
1904 rp = rings->common.sring->req_prod;
1906 /* Ensure we see queued requests up to 'rp'. */
1910 * Run so long as there is work to consume and the generation
1911 * of a response will not overflow the ring.
1913 * @note There's a 1 to 1 relationship between requests and
1914 * responses, so an overflow should never occur. This
1915 * test is to protect our domain from digesting bogus
1916 * data. Shouldn't we log this?
1918 while (rings->common.req_cons != rp
1919 && RING_REQUEST_CONS_OVERFLOW(&rings->common,
1920 rings->common.req_cons) == 0){
1921 blkif_request_t ring_req_storage;
1922 blkif_request_t *ring_req;
1926 case BLKIF_PROTOCOL_NATIVE:
1927 ring_req = RING_GET_REQUEST(&xbb->rings.native,
1928 rings->common.req_cons);
1930 case BLKIF_PROTOCOL_X86_32:
1932 struct blkif_x86_32_request *ring_req32;
1934 ring_req32 = RING_GET_REQUEST(
1935 &xbb->rings.x86_32, rings->common.req_cons);
1936 blkif_get_x86_32_req(&ring_req_storage,
1938 ring_req = &ring_req_storage;
1941 case BLKIF_PROTOCOL_X86_64:
1943 struct blkif_x86_64_request *ring_req64;
1945 ring_req64 =RING_GET_REQUEST(&xbb->rings.x86_64,
1946 rings->common.req_cons);
1947 blkif_get_x86_64_req(&ring_req_storage,
1949 ring_req = &ring_req_storage;
1953 panic("Unexpected blkif protocol ABI.");
1958 * Check for situations that would require closing
1959 * off this I/O for further coalescing:
1960 * - Coalescing is turned off.
1961 * - Current I/O is out of sequence with the previous
1963 * - Coalesced I/O would be too large.
1965 if ((reqlist != NULL)
1966 && ((xbb->no_coalesce_reqs != 0)
1967 || ((xbb->no_coalesce_reqs == 0)
1968 && ((ring_req->sector_number != cur_sector)
1969 || (ring_req->operation != cur_operation)
1970 || ((ring_req->nr_segments + reqlist->nr_segments) >
1971 xbb->max_reqlist_segments))))) {
1976 * Grab and check for all resources in one shot.
1977 * If we can't get all of the resources we need,
1978 * the shortage is noted and the thread will get
1979 * woken up when more resources are available.
1981 retval = xbb_get_resources(xbb, &reqlist, ring_req,
1982 xbb->rings.common.req_cons);
1986 * Resource shortage has been recorded.
1987 * We'll be scheduled to run once a request
1988 * object frees up due to a completion.
1994 * Signify that we can overwrite this request with
1995 * a response by incrementing our consumer index.
1996 * The response won't be generated until after
1997 * we've already consumed all necessary data out
1998 * of the version of the request in the ring buffer
1999 * (for native mode). We must update the consumer
2000 * index before issueing back-end I/O so there is
2001 * no possibility that it will complete and a
2002 * response be generated before we make room in
2003 * the queue for that response.
2005 xbb->rings.common.req_cons +=
2006 BLKIF_SEGS_TO_BLOCKS(ring_req->nr_segments);
2007 xbb->reqs_received++;
2009 cur_size = xbb_count_sects(ring_req);
2010 cur_sector = ring_req->sector_number + cur_size;
2011 reqlist->next_contig_sector = cur_sector;
2012 cur_operation = ring_req->operation;
2015 /* Check for I/O to dispatch */
2016 reqlist = STAILQ_FIRST(&xbb->reqlist_pending_stailq);
2017 if (reqlist == NULL) {
2019 * We're out of work to do, put the task queue to
2026 * Grab the first request off the queue and attempt
2029 STAILQ_REMOVE_HEAD(&xbb->reqlist_pending_stailq, links);
2031 retval = xbb_dispatch_io(xbb, reqlist);
2034 * xbb_dispatch_io() returns non-zero only when
2035 * there is a resource shortage. If that's the
2036 * case, re-queue this request on the head of the
2037 * queue, and go to sleep until we have more
2040 STAILQ_INSERT_HEAD(&xbb->reqlist_pending_stailq,
2045 * If we still have anything on the queue after
2046 * removing the head entry, that is because we
2047 * met one of the criteria to create a new
2048 * request list (outlined above), and we'll call
2049 * that a forced dispatch for statistical purposes.
2051 * Otherwise, if there is only one element on the
2052 * queue, we coalesced everything available on
2053 * the ring and we'll call that a normal dispatch.
2055 reqlist = STAILQ_FIRST(&xbb->reqlist_pending_stailq);
2057 if (reqlist != NULL)
2058 xbb->forced_dispatch++;
2060 xbb->normal_dispatch++;
2062 xbb->total_dispatch++;
2068 * Interrupt handler bound to the shared ring's event channel.
2070 * \param arg Callback argument registerd during event channel
2071 * binding - the xbb_softc for this instance.
2074 xbb_filter(void *arg)
2076 struct xbb_softc *xbb;
2078 /* Defer to taskqueue thread. */
2079 xbb = (struct xbb_softc *)arg;
2080 taskqueue_enqueue(xbb->io_taskqueue, &xbb->io_task);
2082 return (FILTER_HANDLED);
2085 SDT_PROVIDER_DEFINE(xbb);
2086 SDT_PROBE_DEFINE1(xbb, kernel, xbb_dispatch_dev, flush, "int");
2087 SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_dev, read, "int", "uint64_t",
2089 SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_dev, write, "int",
2090 "uint64_t", "uint64_t");
2092 /*----------------------------- Backend Handlers -----------------------------*/
2094 * Backend handler for character device access.
2096 * \param xbb Per-instance xbb configuration structure.
2097 * \param reqlist Allocated internal request list structure.
2098 * \param operation BIO_* I/O operation code.
2099 * \param bio_flags Additional bio_flag data to pass to any generated
2100 * bios (e.g. BIO_ORDERED)..
2102 * \return 0 for success, errno codes for failure.
2105 xbb_dispatch_dev(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist,
2106 int operation, int bio_flags)
2108 struct xbb_dev_data *dev_data;
2109 struct bio *bios[XBB_MAX_SEGMENTS_PER_REQLIST];
2112 struct xbb_sg *xbb_sg;
2119 dev_data = &xbb->backend.dev;
2120 bio_offset = (off_t)reqlist->starting_sector_number
2121 << xbb->sector_size_shift;
2126 if (operation == BIO_FLUSH) {
2128 if (__predict_false(bio == NULL)) {
2129 DPRINTF("Unable to allocate bio for BIO_FLUSH\n");
2134 bio->bio_cmd = BIO_FLUSH;
2135 bio->bio_flags |= BIO_ORDERED;
2136 bio->bio_dev = dev_data->cdev;
2137 bio->bio_offset = 0;
2139 bio->bio_done = xbb_bio_done;
2140 bio->bio_caller1 = reqlist;
2141 bio->bio_pblkno = 0;
2143 reqlist->pendcnt = 1;
2145 SDT_PROBE1(xbb, kernel, xbb_dispatch_dev, flush,
2146 device_get_unit(xbb->dev));
2148 (*dev_data->csw->d_strategy)(bio);
2153 xbb_sg = xbb->xbb_sgs;
2155 nseg = reqlist->nr_segments;
2157 for (seg_idx = 0; seg_idx < nseg; seg_idx++, xbb_sg++) {
2160 * KVA will not be contiguous, so any additional
2161 * I/O will need to be represented in a new bio.
2164 && (xbb_sg->first_sect != 0)) {
2165 if ((bio->bio_length & (xbb->sector_size - 1)) != 0) {
2166 printf("%s: Discontiguous I/O request "
2167 "from domain %d ends on "
2168 "non-sector boundary\n",
2169 __func__, xbb->otherend_id);
2171 goto fail_free_bios;
2178 * Make sure that the start of this bio is
2179 * aligned to a device sector.
2181 if ((bio_offset & (xbb->sector_size - 1)) != 0){
2182 printf("%s: Misaligned I/O request "
2183 "from domain %d\n", __func__,
2186 goto fail_free_bios;
2189 bio = bios[nbio++] = g_new_bio();
2190 if (__predict_false(bio == NULL)) {
2192 goto fail_free_bios;
2194 bio->bio_cmd = operation;
2195 bio->bio_flags |= bio_flags;
2196 bio->bio_dev = dev_data->cdev;
2197 bio->bio_offset = bio_offset;
2198 bio->bio_data = xbb_reqlist_ioaddr(reqlist, seg_idx,
2199 xbb_sg->first_sect);
2200 bio->bio_done = xbb_bio_done;
2201 bio->bio_caller1 = reqlist;
2202 bio->bio_pblkno = bio_offset >> xbb->sector_size_shift;
2205 bio->bio_length += xbb_sg->nsect << 9;
2206 bio->bio_bcount = bio->bio_length;
2207 bio_offset += xbb_sg->nsect << 9;
2209 if (xbb_sg->last_sect != (PAGE_SIZE - 512) >> 9) {
2211 if ((bio->bio_length & (xbb->sector_size - 1)) != 0) {
2212 printf("%s: Discontiguous I/O request "
2213 "from domain %d ends on "
2214 "non-sector boundary\n",
2215 __func__, xbb->otherend_id);
2217 goto fail_free_bios;
2220 * KVA will not be contiguous, so any additional
2221 * I/O will need to be represented in a new bio.
2227 reqlist->pendcnt = nbio;
2229 for (bio_idx = 0; bio_idx < nbio; bio_idx++)
2231 #ifdef XBB_USE_BOUNCE_BUFFERS
2232 vm_offset_t kva_offset;
2234 kva_offset = (vm_offset_t)bios[bio_idx]->bio_data
2235 - (vm_offset_t)reqlist->bounce;
2236 if (operation == BIO_WRITE) {
2237 memcpy(bios[bio_idx]->bio_data,
2238 (uint8_t *)reqlist->kva + kva_offset,
2239 bios[bio_idx]->bio_bcount);
2242 if (operation == BIO_READ) {
2243 SDT_PROBE3(xbb, kernel, xbb_dispatch_dev, read,
2244 device_get_unit(xbb->dev),
2245 bios[bio_idx]->bio_offset,
2246 bios[bio_idx]->bio_length);
2247 } else if (operation == BIO_WRITE) {
2248 SDT_PROBE3(xbb, kernel, xbb_dispatch_dev, write,
2249 device_get_unit(xbb->dev),
2250 bios[bio_idx]->bio_offset,
2251 bios[bio_idx]->bio_length);
2253 (*dev_data->csw->d_strategy)(bios[bio_idx]);
2259 for (bio_idx = 0; bio_idx < (nbio-1); bio_idx++)
2260 g_destroy_bio(bios[bio_idx]);
2265 SDT_PROBE_DEFINE1(xbb, kernel, xbb_dispatch_file, flush, "int");
2266 SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_file, read, "int", "uint64_t",
2268 SDT_PROBE_DEFINE3(xbb, kernel, xbb_dispatch_file, write, "int",
2269 "uint64_t", "uint64_t");
2272 * Backend handler for file access.
2274 * \param xbb Per-instance xbb configuration structure.
2275 * \param reqlist Allocated internal request list.
2276 * \param operation BIO_* I/O operation code.
2277 * \param flags Additional bio_flag data to pass to any generated bios
2278 * (e.g. BIO_ORDERED)..
2280 * \return 0 for success, errno codes for failure.
2283 xbb_dispatch_file(struct xbb_softc *xbb, struct xbb_xen_reqlist *reqlist,
2284 int operation, int flags)
2286 struct xbb_file_data *file_data;
2291 struct xbb_sg *xbb_sg;
2292 struct iovec *xiovec;
2293 #ifdef XBB_USE_BOUNCE_BUFFERS
2295 int saved_uio_iovcnt;
2296 #endif /* XBB_USE_BOUNCE_BUFFERS */
2299 file_data = &xbb->backend.file;
2302 bzero(&xuio, sizeof(xuio));
2304 switch (operation) {
2306 xuio.uio_rw = UIO_READ;
2309 xuio.uio_rw = UIO_WRITE;
2312 struct mount *mountpoint;
2314 SDT_PROBE1(xbb, kernel, xbb_dispatch_file, flush,
2315 device_get_unit(xbb->dev));
2317 (void) vn_start_write(xbb->vn, &mountpoint, V_WAIT);
2319 vn_lock(xbb->vn, LK_EXCLUSIVE | LK_RETRY);
2320 error = VOP_FSYNC(xbb->vn, MNT_WAIT, curthread);
2321 VOP_UNLOCK(xbb->vn, 0);
2323 vn_finished_write(mountpoint);
2325 goto bailout_send_response;
2329 panic("invalid operation %d", operation);
2332 xuio.uio_offset = (vm_offset_t)reqlist->starting_sector_number
2333 << xbb->sector_size_shift;
2334 xuio.uio_segflg = UIO_SYSSPACE;
2335 xuio.uio_iov = file_data->xiovecs;
2336 xuio.uio_iovcnt = 0;
2337 xbb_sg = xbb->xbb_sgs;
2338 nseg = reqlist->nr_segments;
2340 for (xiovec = NULL, seg_idx = 0; seg_idx < nseg; seg_idx++, xbb_sg++) {
2343 * If the first sector is not 0, the KVA will
2344 * not be contiguous and we'll need to go on
2345 * to another segment.
2347 if (xbb_sg->first_sect != 0)
2350 if (xiovec == NULL) {
2351 xiovec = &file_data->xiovecs[xuio.uio_iovcnt];
2352 xiovec->iov_base = xbb_reqlist_ioaddr(reqlist,
2353 seg_idx, xbb_sg->first_sect);
2354 #ifdef XBB_USE_BOUNCE_BUFFERS
2356 * Store the address of the incoming
2357 * buffer at this particular offset
2358 * as well, so we can do the copy
2359 * later without having to do more
2360 * work to recalculate this address.
2362 p_vaddr = &file_data->xiovecs_vaddr[xuio.uio_iovcnt];
2363 *p_vaddr = xbb_reqlist_vaddr(reqlist, seg_idx,
2364 xbb_sg->first_sect);
2365 #endif /* XBB_USE_BOUNCE_BUFFERS */
2366 xiovec->iov_len = 0;
2370 xiovec->iov_len += xbb_sg->nsect << 9;
2372 xuio.uio_resid += xbb_sg->nsect << 9;
2375 * If the last sector is not the full page
2376 * size count, the next segment will not be
2377 * contiguous in KVA and we need a new iovec.
2379 if (xbb_sg->last_sect != (PAGE_SIZE - 512) >> 9)
2383 xuio.uio_td = curthread;
2385 #ifdef XBB_USE_BOUNCE_BUFFERS
2386 saved_uio_iovcnt = xuio.uio_iovcnt;
2388 if (operation == BIO_WRITE) {
2389 /* Copy the write data to the local buffer. */
2390 for (seg_idx = 0, p_vaddr = file_data->xiovecs_vaddr,
2391 xiovec = xuio.uio_iov; seg_idx < xuio.uio_iovcnt;
2392 seg_idx++, xiovec++, p_vaddr++) {
2394 memcpy(xiovec->iov_base, *p_vaddr, xiovec->iov_len);
2398 * We only need to save off the iovecs in the case of a
2399 * read, because the copy for the read happens after the
2400 * VOP_READ(). (The uio will get modified in that call
2403 memcpy(file_data->saved_xiovecs, xuio.uio_iov,
2404 xuio.uio_iovcnt * sizeof(xuio.uio_iov[0]));
2406 #endif /* XBB_USE_BOUNCE_BUFFERS */
2408 switch (operation) {
2411 SDT_PROBE3(xbb, kernel, xbb_dispatch_file, read,
2412 device_get_unit(xbb->dev), xuio.uio_offset,
2415 vn_lock(xbb->vn, LK_EXCLUSIVE | LK_RETRY);
2418 * UFS pays attention to IO_DIRECT for reads. If the
2419 * DIRECTIO option is configured into the kernel, it calls
2420 * ffs_rawread(). But that only works for single-segment
2421 * uios with user space addresses. In our case, with a
2422 * kernel uio, it still reads into the buffer cache, but it
2423 * will just try to release the buffer from the cache later
2426 * ZFS does not pay attention to IO_DIRECT for reads.
2428 * UFS does not pay attention to IO_SYNC for reads.
2430 * ZFS pays attention to IO_SYNC (which translates into the
2431 * Solaris define FRSYNC for zfs_read()) for reads. It
2432 * attempts to sync the file before reading.
2434 * So, to attempt to provide some barrier semantics in the
2435 * BIO_ORDERED case, set both IO_DIRECT and IO_SYNC.
2437 error = VOP_READ(xbb->vn, &xuio, (flags & BIO_ORDERED) ?
2438 (IO_DIRECT|IO_SYNC) : 0, file_data->cred);
2440 VOP_UNLOCK(xbb->vn, 0);
2443 struct mount *mountpoint;
2445 SDT_PROBE3(xbb, kernel, xbb_dispatch_file, write,
2446 device_get_unit(xbb->dev), xuio.uio_offset,
2449 (void)vn_start_write(xbb->vn, &mountpoint, V_WAIT);
2451 vn_lock(xbb->vn, LK_EXCLUSIVE | LK_RETRY);
2454 * UFS pays attention to IO_DIRECT for writes. The write
2455 * is done asynchronously. (Normally the write would just
2456 * get put into cache.
2458 * UFS pays attention to IO_SYNC for writes. It will
2459 * attempt to write the buffer out synchronously if that
2462 * ZFS does not pay attention to IO_DIRECT for writes.
2464 * ZFS pays attention to IO_SYNC (a.k.a. FSYNC or FRSYNC)
2465 * for writes. It will flush the transaction from the
2466 * cache before returning.
2468 * So if we've got the BIO_ORDERED flag set, we want
2469 * IO_SYNC in either the UFS or ZFS case.
2471 error = VOP_WRITE(xbb->vn, &xuio, (flags & BIO_ORDERED) ?
2472 IO_SYNC : 0, file_data->cred);
2473 VOP_UNLOCK(xbb->vn, 0);
2475 vn_finished_write(mountpoint);
2480 panic("invalid operation %d", operation);
2484 #ifdef XBB_USE_BOUNCE_BUFFERS
2485 /* We only need to copy here for read operations */
2486 if (operation == BIO_READ) {
2488 for (seg_idx = 0, p_vaddr = file_data->xiovecs_vaddr,
2489 xiovec = file_data->saved_xiovecs;
2490 seg_idx < saved_uio_iovcnt; seg_idx++,
2491 xiovec++, p_vaddr++) {
2494 * Note that we have to use the copy of the
2495 * io vector we made above. uiomove() modifies
2496 * the uio and its referenced vector as uiomove
2497 * performs the copy, so we can't rely on any
2498 * state from the original uio.
2500 memcpy(*p_vaddr, xiovec->iov_base, xiovec->iov_len);
2503 #endif /* XBB_USE_BOUNCE_BUFFERS */
2505 bailout_send_response:
2508 reqlist->status = BLKIF_RSP_ERROR;
2510 xbb_complete_reqlist(xbb, reqlist);
2515 /*--------------------------- Backend Configuration --------------------------*/
2517 * Close and cleanup any backend device/file specific state for this
2518 * block back instance.
2520 * \param xbb Per-instance xbb configuration structure.
2523 xbb_close_backend(struct xbb_softc *xbb)
2526 DPRINTF("closing dev=%s\n", xbb->dev_name);
2530 if ((xbb->flags & XBBF_READ_ONLY) == 0)
2533 switch (xbb->device_type) {
2535 if (xbb->backend.dev.csw) {
2536 dev_relthread(xbb->backend.dev.cdev,
2537 xbb->backend.dev.dev_ref);
2538 xbb->backend.dev.csw = NULL;
2539 xbb->backend.dev.cdev = NULL;
2546 panic("Unexpected backend type.");
2550 (void)vn_close(xbb->vn, flags, NOCRED, curthread);
2553 switch (xbb->device_type) {
2557 if (xbb->backend.file.cred != NULL) {
2558 crfree(xbb->backend.file.cred);
2559 xbb->backend.file.cred = NULL;
2564 panic("Unexpected backend type.");
2572 * Open a character device to be used for backend I/O.
2574 * \param xbb Per-instance xbb configuration structure.
2576 * \return 0 for success, errno codes for failure.
2579 xbb_open_dev(struct xbb_softc *xbb)
2583 struct cdevsw *devsw;
2586 xbb->device_type = XBB_TYPE_DISK;
2587 xbb->dispatch_io = xbb_dispatch_dev;
2588 xbb->backend.dev.cdev = xbb->vn->v_rdev;
2589 xbb->backend.dev.csw = dev_refthread(xbb->backend.dev.cdev,
2590 &xbb->backend.dev.dev_ref);
2591 if (xbb->backend.dev.csw == NULL)
2592 panic("Unable to retrieve device switch");
2594 error = VOP_GETATTR(xbb->vn, &vattr, NOCRED);
2596 xenbus_dev_fatal(xbb->dev, error, "error getting "
2597 "vnode attributes for device %s",
2603 dev = xbb->vn->v_rdev;
2604 devsw = dev->si_devsw;
2605 if (!devsw->d_ioctl) {
2606 xenbus_dev_fatal(xbb->dev, ENODEV, "no d_ioctl for "
2607 "device %s!", xbb->dev_name);
2611 error = devsw->d_ioctl(dev, DIOCGSECTORSIZE,
2612 (caddr_t)&xbb->sector_size, FREAD,
2615 xenbus_dev_fatal(xbb->dev, error,
2616 "error calling ioctl DIOCGSECTORSIZE "
2617 "for device %s", xbb->dev_name);
2621 error = devsw->d_ioctl(dev, DIOCGMEDIASIZE,
2622 (caddr_t)&xbb->media_size, FREAD,
2625 xenbus_dev_fatal(xbb->dev, error,
2626 "error calling ioctl DIOCGMEDIASIZE "
2627 "for device %s", xbb->dev_name);
2635 * Open a file to be used for backend I/O.
2637 * \param xbb Per-instance xbb configuration structure.
2639 * \return 0 for success, errno codes for failure.
2642 xbb_open_file(struct xbb_softc *xbb)
2644 struct xbb_file_data *file_data;
2648 file_data = &xbb->backend.file;
2649 xbb->device_type = XBB_TYPE_FILE;
2650 xbb->dispatch_io = xbb_dispatch_file;
2651 error = VOP_GETATTR(xbb->vn, &vattr, curthread->td_ucred);
2653 xenbus_dev_fatal(xbb->dev, error,
2654 "error calling VOP_GETATTR()"
2655 "for file %s", xbb->dev_name);
2660 * Verify that we have the ability to upgrade to exclusive
2661 * access on this file so we can trap errors at open instead
2662 * of reporting them during first access.
2664 if (VOP_ISLOCKED(xbb->vn) != LK_EXCLUSIVE) {
2665 vn_lock(xbb->vn, LK_UPGRADE | LK_RETRY);
2666 if (xbb->vn->v_iflag & VI_DOOMED) {
2668 xenbus_dev_fatal(xbb->dev, error,
2669 "error locking file %s",
2676 file_data->cred = crhold(curthread->td_ucred);
2677 xbb->media_size = vattr.va_size;
2680 * XXX KDM vattr.va_blocksize may be larger than 512 bytes here.
2681 * With ZFS, it is 131072 bytes. Block sizes that large don't work
2682 * with disklabel and UFS on FreeBSD at least. Large block sizes
2683 * may not work with other OSes as well. So just export a sector
2684 * size of 512 bytes, which should work with any OS or
2685 * application. Since our backing is a file, any block size will
2686 * work fine for the backing store.
2689 xbb->sector_size = vattr.va_blocksize;
2691 xbb->sector_size = 512;
2694 * Sanity check. The media size has to be at least one
2697 if (xbb->media_size < xbb->sector_size) {
2699 xenbus_dev_fatal(xbb->dev, error,
2700 "file %s size %ju < block size %u",
2702 (uintmax_t)xbb->media_size,
2709 * Open the backend provider for this connection.
2711 * \param xbb Per-instance xbb configuration structure.
2713 * \return 0 for success, errno codes for failure.
2716 xbb_open_backend(struct xbb_softc *xbb)
2718 struct nameidata nd;
2725 DPRINTF("opening dev=%s\n", xbb->dev_name);
2727 if (rootvnode == NULL) {
2728 xenbus_dev_fatal(xbb->dev, ENOENT,
2729 "Root file system not mounted");
2733 if ((xbb->flags & XBBF_READ_ONLY) == 0)
2736 if (!curthread->td_proc->p_fd->fd_cdir) {
2737 curthread->td_proc->p_fd->fd_cdir = rootvnode;
2740 if (!curthread->td_proc->p_fd->fd_rdir) {
2741 curthread->td_proc->p_fd->fd_rdir = rootvnode;
2744 if (!curthread->td_proc->p_fd->fd_jdir) {
2745 curthread->td_proc->p_fd->fd_jdir = rootvnode;
2750 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, xbb->dev_name, curthread);
2751 error = vn_open(&nd, &flags, 0, NULL);
2754 * This is the only reasonable guess we can make as far as
2755 * path if the user doesn't give us a fully qualified path.
2756 * If they want to specify a file, they need to specify the
2759 if (xbb->dev_name[0] != '/') {
2760 char *dev_path = "/dev/";
2763 /* Try adding device path at beginning of name */
2764 dev_name = malloc(strlen(xbb->dev_name)
2765 + strlen(dev_path) + 1,
2766 M_XENBLOCKBACK, M_NOWAIT);
2768 sprintf(dev_name, "%s%s", dev_path,
2770 free(xbb->dev_name, M_XENBLOCKBACK);
2771 xbb->dev_name = dev_name;
2775 xenbus_dev_fatal(xbb->dev, error, "error opening device %s",
2780 NDFREE(&nd, NDF_ONLY_PNBUF);
2784 /* We only support disks and files. */
2785 if (vn_isdisk(xbb->vn, &error)) {
2786 error = xbb_open_dev(xbb);
2787 } else if (xbb->vn->v_type == VREG) {
2788 error = xbb_open_file(xbb);
2791 xenbus_dev_fatal(xbb->dev, error, "%s is not a disk "
2792 "or file", xbb->dev_name);
2794 VOP_UNLOCK(xbb->vn, 0);
2797 xbb_close_backend(xbb);
2801 xbb->sector_size_shift = fls(xbb->sector_size) - 1;
2802 xbb->media_num_sectors = xbb->media_size >> xbb->sector_size_shift;
2804 DPRINTF("opened %s=%s sector_size=%u media_size=%" PRId64 "\n",
2805 (xbb->device_type == XBB_TYPE_DISK) ? "dev" : "file",
2806 xbb->dev_name, xbb->sector_size, xbb->media_size);
2811 /*------------------------ Inter-Domain Communication ------------------------*/
2813 * Free dynamically allocated KVA or pseudo-physical address allocations.
2815 * \param xbb Per-instance xbb configuration structure.
2818 xbb_free_communication_mem(struct xbb_softc *xbb)
2820 if (xbb->kva != 0) {
2822 kva_free(xbb->kva, xbb->kva_size);
2824 if (xbb->pseudo_phys_res != NULL) {
2825 bus_release_resource(xbb->dev, SYS_RES_MEMORY,
2826 xbb->pseudo_phys_res_id,
2827 xbb->pseudo_phys_res);
2828 xbb->pseudo_phys_res = NULL;
2833 xbb->gnt_base_addr = 0;
2834 if (xbb->kva_free != NULL) {
2835 free(xbb->kva_free, M_XENBLOCKBACK);
2836 xbb->kva_free = NULL;
2841 * Cleanup all inter-domain communication mechanisms.
2843 * \param xbb Per-instance xbb configuration structure.
2846 xbb_disconnect(struct xbb_softc *xbb)
2848 struct gnttab_unmap_grant_ref ops[XBB_MAX_RING_PAGES];
2849 struct gnttab_unmap_grant_ref *op;
2855 if ((xbb->flags & XBBF_RING_CONNECTED) == 0)
2858 xen_intr_unbind(&xbb->xen_intr_handle);
2860 mtx_unlock(&xbb->lock);
2861 taskqueue_drain(xbb->io_taskqueue, &xbb->io_task);
2862 mtx_lock(&xbb->lock);
2865 * No new interrupts can generate work, but we must wait
2866 * for all currently active requests to drain.
2868 if (xbb->active_request_count != 0)
2871 for (ring_idx = 0, op = ops;
2872 ring_idx < xbb->ring_config.ring_pages;
2875 op->host_addr = xbb->ring_config.gnt_addr
2876 + (ring_idx * PAGE_SIZE);
2877 op->dev_bus_addr = xbb->ring_config.bus_addr[ring_idx];
2878 op->handle = xbb->ring_config.handle[ring_idx];
2881 error = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, ops,
2882 xbb->ring_config.ring_pages);
2884 panic("Grant table op failed (%d)", error);
2886 xbb_free_communication_mem(xbb);
2888 if (xbb->requests != NULL) {
2889 free(xbb->requests, M_XENBLOCKBACK);
2890 xbb->requests = NULL;
2893 if (xbb->request_lists != NULL) {
2894 struct xbb_xen_reqlist *reqlist;
2897 /* There is one request list for ever allocated request. */
2898 for (i = 0, reqlist = xbb->request_lists;
2899 i < xbb->max_requests; i++, reqlist++){
2900 #ifdef XBB_USE_BOUNCE_BUFFERS
2901 if (reqlist->bounce != NULL) {
2902 free(reqlist->bounce, M_XENBLOCKBACK);
2903 reqlist->bounce = NULL;
2906 if (reqlist->gnt_handles != NULL) {
2907 free(reqlist->gnt_handles, M_XENBLOCKBACK);
2908 reqlist->gnt_handles = NULL;
2911 free(xbb->request_lists, M_XENBLOCKBACK);
2912 xbb->request_lists = NULL;
2915 xbb->flags &= ~XBBF_RING_CONNECTED;
2920 * Map shared memory ring into domain local address space, initialize
2921 * ring control structures, and bind an interrupt to the event channel
2922 * used to notify us of ring changes.
2924 * \param xbb Per-instance xbb configuration structure.
2927 xbb_connect_ring(struct xbb_softc *xbb)
2929 struct gnttab_map_grant_ref gnts[XBB_MAX_RING_PAGES];
2930 struct gnttab_map_grant_ref *gnt;
2934 if ((xbb->flags & XBBF_RING_CONNECTED) != 0)
2938 * Kva for our ring is at the tail of the region of kva allocated
2939 * by xbb_alloc_communication_mem().
2941 xbb->ring_config.va = xbb->kva
2943 - (xbb->ring_config.ring_pages * PAGE_SIZE));
2944 xbb->ring_config.gnt_addr = xbb->gnt_base_addr
2946 - (xbb->ring_config.ring_pages * PAGE_SIZE));
2948 for (ring_idx = 0, gnt = gnts;
2949 ring_idx < xbb->ring_config.ring_pages;
2950 ring_idx++, gnt++) {
2952 gnt->host_addr = xbb->ring_config.gnt_addr
2953 + (ring_idx * PAGE_SIZE);
2954 gnt->flags = GNTMAP_host_map;
2955 gnt->ref = xbb->ring_config.ring_ref[ring_idx];
2956 gnt->dom = xbb->otherend_id;
2959 error = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, gnts,
2960 xbb->ring_config.ring_pages);
2962 panic("blkback: Ring page grant table op failed (%d)", error);
2964 for (ring_idx = 0, gnt = gnts;
2965 ring_idx < xbb->ring_config.ring_pages;
2966 ring_idx++, gnt++) {
2967 if (gnt->status != 0) {
2968 xbb->ring_config.va = 0;
2969 xenbus_dev_fatal(xbb->dev, EACCES,
2970 "Ring shared page mapping failed. "
2971 "Status %d.", gnt->status);
2974 xbb->ring_config.handle[ring_idx] = gnt->handle;
2975 xbb->ring_config.bus_addr[ring_idx] = gnt->dev_bus_addr;
2978 /* Initialize the ring based on ABI. */
2980 case BLKIF_PROTOCOL_NATIVE:
2982 blkif_sring_t *sring;
2983 sring = (blkif_sring_t *)xbb->ring_config.va;
2984 BACK_RING_INIT(&xbb->rings.native, sring,
2985 xbb->ring_config.ring_pages * PAGE_SIZE);
2988 case BLKIF_PROTOCOL_X86_32:
2990 blkif_x86_32_sring_t *sring_x86_32;
2991 sring_x86_32 = (blkif_x86_32_sring_t *)xbb->ring_config.va;
2992 BACK_RING_INIT(&xbb->rings.x86_32, sring_x86_32,
2993 xbb->ring_config.ring_pages * PAGE_SIZE);
2996 case BLKIF_PROTOCOL_X86_64:
2998 blkif_x86_64_sring_t *sring_x86_64;
2999 sring_x86_64 = (blkif_x86_64_sring_t *)xbb->ring_config.va;
3000 BACK_RING_INIT(&xbb->rings.x86_64, sring_x86_64,
3001 xbb->ring_config.ring_pages * PAGE_SIZE);
3005 panic("Unexpected blkif protocol ABI.");
3008 xbb->flags |= XBBF_RING_CONNECTED;
3010 error = xen_intr_bind_remote_port(xbb->dev,
3012 xbb->ring_config.evtchn,
3014 /*ithread_handler*/NULL,
3016 INTR_TYPE_BIO | INTR_MPSAFE,
3017 &xbb->xen_intr_handle);
3019 (void)xbb_disconnect(xbb);
3020 xenbus_dev_fatal(xbb->dev, error, "binding event channel");
3024 DPRINTF("rings connected!\n");
3029 /* Needed to make bit_alloc() macro work */
3030 #define calloc(count, size) malloc((count)*(size), M_XENBLOCKBACK, \
3034 * Size KVA and pseudo-physical address allocations based on negotiated
3035 * values for the size and number of I/O requests, and the size of our
3036 * communication ring.
3038 * \param xbb Per-instance xbb configuration structure.
3040 * These address spaces are used to dynamically map pages in the
3041 * front-end's domain into our own.
3044 xbb_alloc_communication_mem(struct xbb_softc *xbb)
3046 xbb->reqlist_kva_pages = xbb->max_requests * xbb->max_request_segments;
3047 xbb->reqlist_kva_size = xbb->reqlist_kva_pages * PAGE_SIZE;
3048 xbb->kva_size = xbb->reqlist_kva_size +
3049 (xbb->ring_config.ring_pages * PAGE_SIZE);
3051 xbb->kva_free = bit_alloc(xbb->reqlist_kva_pages);
3052 if (xbb->kva_free == NULL)
3055 DPRINTF("%s: kva_size = %d, reqlist_kva_size = %d\n",
3056 device_get_nameunit(xbb->dev), xbb->kva_size,
3057 xbb->reqlist_kva_size);
3059 xbb->kva = kva_alloc(xbb->kva_size);
3062 xbb->gnt_base_addr = xbb->kva;
3065 * Reserve a range of pseudo physical memory that we can map
3066 * into kva. These pages will only be backed by machine
3067 * pages ("real memory") during the lifetime of front-end requests
3068 * via grant table operations.
3070 xbb->pseudo_phys_res_id = 0;
3071 xbb->pseudo_phys_res = bus_alloc_resource(xbb->dev, SYS_RES_MEMORY,
3072 &xbb->pseudo_phys_res_id,
3073 0, ~0, xbb->kva_size,
3075 if (xbb->pseudo_phys_res == NULL) {
3079 xbb->kva = (vm_offset_t)rman_get_virtual(xbb->pseudo_phys_res);
3080 xbb->gnt_base_addr = rman_get_start(xbb->pseudo_phys_res);
3083 DPRINTF("%s: kva: %#jx, gnt_base_addr: %#jx\n",
3084 device_get_nameunit(xbb->dev), (uintmax_t)xbb->kva,
3085 (uintmax_t)xbb->gnt_base_addr);
3090 * Collect front-end information from the XenStore.
3092 * \param xbb Per-instance xbb configuration structure.
3095 xbb_collect_frontend_info(struct xbb_softc *xbb)
3097 char protocol_abi[64];
3098 const char *otherend_path;
3101 u_int ring_page_order;
3104 otherend_path = xenbus_get_otherend_path(xbb->dev);
3107 * Protocol defaults valid even if all negotiation fails.
3109 xbb->ring_config.ring_pages = 1;
3110 xbb->max_request_segments = BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK;
3111 xbb->max_request_size = xbb->max_request_segments * PAGE_SIZE;
3114 * Mandatory data (used in all versions of the protocol) first.
3116 error = xs_scanf(XST_NIL, otherend_path,
3117 "event-channel", NULL, "%" PRIu32,
3118 &xbb->ring_config.evtchn);
3120 xenbus_dev_fatal(xbb->dev, error,
3121 "Unable to retrieve event-channel information "
3122 "from frontend %s. Unable to connect.",
3123 xenbus_get_otherend_path(xbb->dev));
3128 * These fields are initialized to legacy protocol defaults
3129 * so we only need to fail if reading the updated value succeeds
3130 * and the new value is outside of its allowed range.
3132 * \note xs_gather() returns on the first encountered error, so
3133 * we must use independant calls in order to guarantee
3134 * we don't miss information in a sparsly populated front-end
3137 * \note xs_scanf() does not update variables for unmatched
3140 ring_page_order = 0;
3141 (void)xs_scanf(XST_NIL, otherend_path,
3142 "ring-page-order", NULL, "%u",
3144 xbb->ring_config.ring_pages = 1 << ring_page_order;
3145 (void)xs_scanf(XST_NIL, otherend_path,
3146 "num-ring-pages", NULL, "%u",
3147 &xbb->ring_config.ring_pages);
3148 ring_size = PAGE_SIZE * xbb->ring_config.ring_pages;
3149 xbb->max_requests = BLKIF_MAX_RING_REQUESTS(ring_size);
3151 (void)xs_scanf(XST_NIL, otherend_path,
3152 "max-requests", NULL, "%u",
3153 &xbb->max_requests);
3155 (void)xs_scanf(XST_NIL, otherend_path,
3156 "max-request-segments", NULL, "%u",
3157 &xbb->max_request_segments);
3159 (void)xs_scanf(XST_NIL, otherend_path,
3160 "max-request-size", NULL, "%u",
3161 &xbb->max_request_size);
3163 if (xbb->ring_config.ring_pages > XBB_MAX_RING_PAGES) {
3164 xenbus_dev_fatal(xbb->dev, EINVAL,
3165 "Front-end specified ring-pages of %u "
3166 "exceeds backend limit of %zu. "
3167 "Unable to connect.",
3168 xbb->ring_config.ring_pages,
3169 XBB_MAX_RING_PAGES);
3171 } else if (xbb->max_requests > XBB_MAX_REQUESTS) {
3172 xenbus_dev_fatal(xbb->dev, EINVAL,
3173 "Front-end specified max_requests of %u "
3174 "exceeds backend limit of %u. "
3175 "Unable to connect.",
3179 } else if (xbb->max_request_segments > XBB_MAX_SEGMENTS_PER_REQUEST) {
3180 xenbus_dev_fatal(xbb->dev, EINVAL,
3181 "Front-end specified max_requests_segments "
3182 "of %u exceeds backend limit of %u. "
3183 "Unable to connect.",
3184 xbb->max_request_segments,
3185 XBB_MAX_SEGMENTS_PER_REQUEST);
3187 } else if (xbb->max_request_size > XBB_MAX_REQUEST_SIZE) {
3188 xenbus_dev_fatal(xbb->dev, EINVAL,
3189 "Front-end specified max_request_size "
3190 "of %u exceeds backend limit of %u. "
3191 "Unable to connect.",
3192 xbb->max_request_size,
3193 XBB_MAX_REQUEST_SIZE);
3197 if (xbb->ring_config.ring_pages == 1) {
3198 error = xs_gather(XST_NIL, otherend_path,
3199 "ring-ref", "%" PRIu32,
3200 &xbb->ring_config.ring_ref[0],
3203 xenbus_dev_fatal(xbb->dev, error,
3204 "Unable to retrieve ring information "
3205 "from frontend %s. Unable to "
3207 xenbus_get_otherend_path(xbb->dev));
3211 /* Multi-page ring format. */
3212 for (ring_idx = 0; ring_idx < xbb->ring_config.ring_pages;
3214 char ring_ref_name[]= "ring_refXX";
3216 snprintf(ring_ref_name, sizeof(ring_ref_name),
3217 "ring-ref%u", ring_idx);
3218 error = xs_scanf(XST_NIL, otherend_path,
3219 ring_ref_name, NULL, "%" PRIu32,
3220 &xbb->ring_config.ring_ref[ring_idx]);
3222 xenbus_dev_fatal(xbb->dev, error,
3223 "Failed to retriev grant "
3224 "reference for page %u of "
3225 "shared ring. Unable "
3226 "to connect.", ring_idx);
3232 error = xs_gather(XST_NIL, otherend_path,
3233 "protocol", "%63s", protocol_abi,
3236 || !strcmp(protocol_abi, XEN_IO_PROTO_ABI_NATIVE)) {
3238 * Assume native if the frontend has not
3239 * published ABI data or it has published and
3240 * matches our own ABI.
3242 xbb->abi = BLKIF_PROTOCOL_NATIVE;
3243 } else if (!strcmp(protocol_abi, XEN_IO_PROTO_ABI_X86_32)) {
3245 xbb->abi = BLKIF_PROTOCOL_X86_32;
3246 } else if (!strcmp(protocol_abi, XEN_IO_PROTO_ABI_X86_64)) {
3248 xbb->abi = BLKIF_PROTOCOL_X86_64;
3251 xenbus_dev_fatal(xbb->dev, EINVAL,
3252 "Unknown protocol ABI (%s) published by "
3253 "frontend. Unable to connect.", protocol_abi);
3260 * Allocate per-request data structures given request size and number
3261 * information negotiated with the front-end.
3263 * \param xbb Per-instance xbb configuration structure.
3266 xbb_alloc_requests(struct xbb_softc *xbb)
3268 struct xbb_xen_req *req;
3269 struct xbb_xen_req *last_req;
3272 * Allocate request book keeping datastructures.
3274 xbb->requests = malloc(xbb->max_requests * sizeof(*xbb->requests),
3275 M_XENBLOCKBACK, M_NOWAIT|M_ZERO);
3276 if (xbb->requests == NULL) {
3277 xenbus_dev_fatal(xbb->dev, ENOMEM,
3278 "Unable to allocate request structures");
3282 req = xbb->requests;
3283 last_req = &xbb->requests[xbb->max_requests - 1];
3284 STAILQ_INIT(&xbb->request_free_stailq);
3285 while (req <= last_req) {
3286 STAILQ_INSERT_TAIL(&xbb->request_free_stailq, req, links);
3293 xbb_alloc_request_lists(struct xbb_softc *xbb)
3295 struct xbb_xen_reqlist *reqlist;
3299 * If no requests can be merged, we need 1 request list per
3300 * in flight request.
3302 xbb->request_lists = malloc(xbb->max_requests *
3303 sizeof(*xbb->request_lists), M_XENBLOCKBACK, M_NOWAIT|M_ZERO);
3304 if (xbb->request_lists == NULL) {
3305 xenbus_dev_fatal(xbb->dev, ENOMEM,
3306 "Unable to allocate request list structures");
3310 STAILQ_INIT(&xbb->reqlist_free_stailq);
3311 STAILQ_INIT(&xbb->reqlist_pending_stailq);
3312 for (i = 0; i < xbb->max_requests; i++) {
3315 reqlist = &xbb->request_lists[i];
3319 #ifdef XBB_USE_BOUNCE_BUFFERS
3320 reqlist->bounce = malloc(xbb->max_reqlist_size,
3321 M_XENBLOCKBACK, M_NOWAIT);
3322 if (reqlist->bounce == NULL) {
3323 xenbus_dev_fatal(xbb->dev, ENOMEM,
3324 "Unable to allocate request "
3328 #endif /* XBB_USE_BOUNCE_BUFFERS */
3330 reqlist->gnt_handles = malloc(xbb->max_reqlist_segments *
3331 sizeof(*reqlist->gnt_handles),
3332 M_XENBLOCKBACK, M_NOWAIT|M_ZERO);
3333 if (reqlist->gnt_handles == NULL) {
3334 xenbus_dev_fatal(xbb->dev, ENOMEM,
3335 "Unable to allocate request "
3336 "grant references");
3340 for (seg = 0; seg < xbb->max_reqlist_segments; seg++)
3341 reqlist->gnt_handles[seg] = GRANT_REF_INVALID;
3343 STAILQ_INSERT_TAIL(&xbb->reqlist_free_stailq, reqlist, links);
3349 * Supply information about the physical device to the frontend
3352 * \param xbb Per-instance xbb configuration structure.
3355 xbb_publish_backend_info(struct xbb_softc *xbb)
3357 struct xs_transaction xst;
3358 const char *our_path;
3362 our_path = xenbus_get_node(xbb->dev);
3364 error = xs_transaction_start(&xst);
3366 xenbus_dev_fatal(xbb->dev, error,
3367 "Error publishing backend info "
3368 "(start transaction)");
3373 error = xs_printf(xst, our_path, leaf,
3374 "%"PRIu64, xbb->media_num_sectors);
3378 /* XXX Support all VBD attributes here. */
3380 error = xs_printf(xst, our_path, leaf, "%u",
3381 xbb->flags & XBBF_READ_ONLY
3382 ? VDISK_READONLY : 0);
3386 leaf = "sector-size";
3387 error = xs_printf(xst, our_path, leaf, "%u",
3392 error = xs_transaction_end(xst, 0);
3395 } else if (error != EAGAIN) {
3396 xenbus_dev_fatal(xbb->dev, error, "ending transaction");
3401 xenbus_dev_fatal(xbb->dev, error, "writing %s/%s",
3403 xs_transaction_end(xst, 1);
3408 * Connect to our blkfront peer now that it has completed publishing
3409 * its configuration into the XenStore.
3411 * \param xbb Per-instance xbb configuration structure.
3414 xbb_connect(struct xbb_softc *xbb)
3418 if (xenbus_get_state(xbb->dev) == XenbusStateConnected)
3421 if (xbb_collect_frontend_info(xbb) != 0)
3424 xbb->flags &= ~XBBF_SHUTDOWN;
3427 * We limit the maximum number of reqlist segments to the maximum
3428 * number of segments in the ring, or our absolute maximum,
3429 * whichever is smaller.
3431 xbb->max_reqlist_segments = MIN(xbb->max_request_segments *
3432 xbb->max_requests, XBB_MAX_SEGMENTS_PER_REQLIST);
3435 * The maximum size is simply a function of the number of segments
3438 xbb->max_reqlist_size = xbb->max_reqlist_segments * PAGE_SIZE;
3440 /* Allocate resources whose size depends on front-end configuration. */
3441 error = xbb_alloc_communication_mem(xbb);
3443 xenbus_dev_fatal(xbb->dev, error,
3444 "Unable to allocate communication memory");
3448 error = xbb_alloc_requests(xbb);
3450 /* Specific errors are reported by xbb_alloc_requests(). */
3454 error = xbb_alloc_request_lists(xbb);
3456 /* Specific errors are reported by xbb_alloc_request_lists(). */
3461 * Connect communication channel.
3463 error = xbb_connect_ring(xbb);
3465 /* Specific errors are reported by xbb_connect_ring(). */
3469 if (xbb_publish_backend_info(xbb) != 0) {
3471 * If we can't publish our data, we cannot participate
3472 * in this connection, and waiting for a front-end state
3473 * change will not help the situation.
3475 (void)xbb_disconnect(xbb);
3479 /* Ready for I/O. */
3480 xenbus_set_state(xbb->dev, XenbusStateConnected);
3483 /*-------------------------- Device Teardown Support -------------------------*/
3485 * Perform device shutdown functions.
3487 * \param xbb Per-instance xbb configuration structure.
3489 * Mark this instance as shutting down, wait for any active I/O on the
3490 * backend device/file to drain, disconnect from the front-end, and notify
3491 * any waiters (e.g. a thread invoking our detach method) that detach can
3495 xbb_shutdown(struct xbb_softc *xbb)
3497 XenbusState frontState;
3503 * Due to the need to drop our mutex during some
3504 * xenbus operations, it is possible for two threads
3505 * to attempt to close out shutdown processing at
3506 * the same time. Tell the caller that hits this
3507 * race to try back later.
3509 if ((xbb->flags & XBBF_IN_SHUTDOWN) != 0)
3512 xbb->flags |= XBBF_IN_SHUTDOWN;
3513 mtx_unlock(&xbb->lock);
3515 if (xenbus_get_state(xbb->dev) < XenbusStateClosing)
3516 xenbus_set_state(xbb->dev, XenbusStateClosing);
3518 frontState = xenbus_get_otherend_state(xbb->dev);
3519 mtx_lock(&xbb->lock);
3520 xbb->flags &= ~XBBF_IN_SHUTDOWN;
3522 /* The front can submit I/O until entering the closed state. */
3523 if (frontState < XenbusStateClosed)
3528 /* Indicate shutdown is in progress. */
3529 xbb->flags |= XBBF_SHUTDOWN;
3531 /* Disconnect from the front-end. */
3532 error = xbb_disconnect(xbb);
3535 * Requests still outstanding. We'll be called again
3536 * once they complete.
3538 KASSERT(error == EAGAIN,
3539 ("%s: Unexpected xbb_disconnect() failure %d",
3547 /* Indicate to xbb_detach() that is it safe to proceed. */
3554 * Report an attach time error to the console and Xen, and cleanup
3555 * this instance by forcing immediate detach processing.
3557 * \param xbb Per-instance xbb configuration structure.
3558 * \param err Errno describing the error.
3559 * \param fmt Printf style format and arguments
3562 xbb_attach_failed(struct xbb_softc *xbb, int err, const char *fmt, ...)
3568 va_copy(ap_hotplug, ap);
3569 xs_vprintf(XST_NIL, xenbus_get_node(xbb->dev),
3570 "hotplug-error", fmt, ap_hotplug);
3572 xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3573 "hotplug-status", "error");
3575 xenbus_dev_vfatal(xbb->dev, err, fmt, ap);
3578 xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3580 xbb_detach(xbb->dev);
3583 /*---------------------------- NewBus Entrypoints ----------------------------*/
3585 * Inspect a XenBus device and claim it if is of the appropriate type.
3587 * \param dev NewBus device object representing a candidate XenBus device.
3589 * \return 0 for success, errno codes for failure.
3592 xbb_probe(device_t dev)
3595 if (!strcmp(xenbus_get_type(dev), "vbd")) {
3596 device_set_desc(dev, "Backend Virtual Block Device");
3605 * Setup sysctl variables to control various Block Back parameters.
3607 * \param xbb Xen Block Back softc.
3611 xbb_setup_sysctl(struct xbb_softc *xbb)
3613 struct sysctl_ctx_list *sysctl_ctx = NULL;
3614 struct sysctl_oid *sysctl_tree = NULL;
3616 sysctl_ctx = device_get_sysctl_ctx(xbb->dev);
3617 if (sysctl_ctx == NULL)
3620 sysctl_tree = device_get_sysctl_tree(xbb->dev);
3621 if (sysctl_tree == NULL)
3624 SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3625 "disable_flush", CTLFLAG_RW, &xbb->disable_flush, 0,
3626 "fake the flush command");
3628 SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3629 "flush_interval", CTLFLAG_RW, &xbb->flush_interval, 0,
3630 "send a real flush for N flush requests");
3632 SYSCTL_ADD_INT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3633 "no_coalesce_reqs", CTLFLAG_RW, &xbb->no_coalesce_reqs,0,
3634 "Don't coalesce contiguous requests");
3636 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3637 "reqs_received", CTLFLAG_RW, &xbb->reqs_received,
3638 "how many I/O requests we have received");
3640 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3641 "reqs_completed", CTLFLAG_RW, &xbb->reqs_completed,
3642 "how many I/O requests have been completed");
3644 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3645 "reqs_queued_for_completion", CTLFLAG_RW,
3646 &xbb->reqs_queued_for_completion,
3647 "how many I/O requests queued but not yet pushed");
3649 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3650 "reqs_completed_with_error", CTLFLAG_RW,
3651 &xbb->reqs_completed_with_error,
3652 "how many I/O requests completed with error status");
3654 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3655 "forced_dispatch", CTLFLAG_RW, &xbb->forced_dispatch,
3656 "how many I/O dispatches were forced");
3658 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3659 "normal_dispatch", CTLFLAG_RW, &xbb->normal_dispatch,
3660 "how many I/O dispatches were normal");
3662 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3663 "total_dispatch", CTLFLAG_RW, &xbb->total_dispatch,
3664 "total number of I/O dispatches");
3666 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3667 "kva_shortages", CTLFLAG_RW, &xbb->kva_shortages,
3668 "how many times we have run out of KVA");
3670 SYSCTL_ADD_UQUAD(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3671 "request_shortages", CTLFLAG_RW,
3672 &xbb->request_shortages,
3673 "how many times we have run out of requests");
3675 SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3676 "max_requests", CTLFLAG_RD, &xbb->max_requests, 0,
3677 "maximum outstanding requests (negotiated)");
3679 SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3680 "max_request_segments", CTLFLAG_RD,
3681 &xbb->max_request_segments, 0,
3682 "maximum number of pages per requests (negotiated)");
3684 SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3685 "max_request_size", CTLFLAG_RD,
3686 &xbb->max_request_size, 0,
3687 "maximum size in bytes of a request (negotiated)");
3689 SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
3690 "ring_pages", CTLFLAG_RD,
3691 &xbb->ring_config.ring_pages, 0,
3692 "communication channel pages (negotiated)");
3696 * Attach to a XenBus device that has been claimed by our probe routine.
3698 * \param dev NewBus device object representing this Xen Block Back instance.
3700 * \return 0 for success, errno codes for failure.
3703 xbb_attach(device_t dev)
3705 struct xbb_softc *xbb;
3707 u_int max_ring_page_order;
3709 DPRINTF("Attaching to %s\n", xenbus_get_node(dev));
3712 * Basic initialization.
3713 * After this block it is safe to call xbb_detach()
3714 * to clean up any allocated data for this instance.
3716 xbb = device_get_softc(dev);
3718 xbb->otherend_id = xenbus_get_otherend_id(dev);
3719 TASK_INIT(&xbb->io_task, /*priority*/0, xbb_run_queue, xbb);
3720 mtx_init(&xbb->lock, device_get_nameunit(dev), NULL, MTX_DEF);
3723 * Publish protocol capabilities for consumption by the
3726 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3727 "feature-barrier", "1");
3729 xbb_attach_failed(xbb, error, "writing %s/feature-barrier",
3730 xenbus_get_node(xbb->dev));
3734 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3735 "feature-flush-cache", "1");
3737 xbb_attach_failed(xbb, error, "writing %s/feature-flush-cache",
3738 xenbus_get_node(xbb->dev));
3743 * Amazon EC2 client compatility. They refer to max-ring-pages
3744 * instead of to max-ring-page-order.
3746 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3747 "max-ring-pages", "%zu", XBB_MAX_RING_PAGES);
3749 xbb_attach_failed(xbb, error, "writing %s/max-ring-pages",
3750 xenbus_get_node(xbb->dev));
3754 max_ring_page_order = flsl(XBB_MAX_RING_PAGES) - 1;
3755 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3756 "max-ring-page-order", "%u", max_ring_page_order);
3758 xbb_attach_failed(xbb, error, "writing %s/max-ring-page-order",
3759 xenbus_get_node(xbb->dev));
3763 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3764 "max-requests", "%u", XBB_MAX_REQUESTS);
3766 xbb_attach_failed(xbb, error, "writing %s/max-requests",
3767 xenbus_get_node(xbb->dev));
3771 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3772 "max-request-segments", "%u",
3773 XBB_MAX_SEGMENTS_PER_REQUEST);
3775 xbb_attach_failed(xbb, error, "writing %s/max-request-segments",
3776 xenbus_get_node(xbb->dev));
3780 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3781 "max-request-size", "%u",
3782 XBB_MAX_REQUEST_SIZE);
3784 xbb_attach_failed(xbb, error, "writing %s/max-request-size",
3785 xenbus_get_node(xbb->dev));
3789 /* Collect physical device information. */
3790 error = xs_gather(XST_NIL, xenbus_get_otherend_path(xbb->dev),
3791 "device-type", NULL, &xbb->dev_type,
3794 xbb->dev_type = NULL;
3796 error = xs_gather(XST_NIL, xenbus_get_node(dev),
3797 "mode", NULL, &xbb->dev_mode,
3798 "params", NULL, &xbb->dev_name,
3801 xbb_attach_failed(xbb, error, "reading backend fields at %s",
3802 xenbus_get_node(dev));
3806 /* Parse fopen style mode flags. */
3807 if (strchr(xbb->dev_mode, 'w') == NULL)
3808 xbb->flags |= XBBF_READ_ONLY;
3811 * Verify the physical device is present and can support
3812 * the desired I/O mode.
3815 error = xbb_open_backend(xbb);
3818 xbb_attach_failed(xbb, error, "Unable to open %s",
3823 /* Use devstat(9) for recording statistics. */
3824 xbb->xbb_stats = devstat_new_entry("xbb", device_get_unit(xbb->dev),
3826 DEVSTAT_ALL_SUPPORTED,
3828 | DEVSTAT_TYPE_IF_OTHER,
3829 DEVSTAT_PRIORITY_OTHER);
3831 xbb->xbb_stats_in = devstat_new_entry("xbbi", device_get_unit(xbb->dev),
3833 DEVSTAT_ALL_SUPPORTED,
3835 | DEVSTAT_TYPE_IF_OTHER,
3836 DEVSTAT_PRIORITY_OTHER);
3838 * Setup sysctl variables.
3840 xbb_setup_sysctl(xbb);
3843 * Create a taskqueue for doing work that must occur from a
3846 xbb->io_taskqueue = taskqueue_create_fast(device_get_nameunit(dev),
3848 taskqueue_thread_enqueue,
3849 /*contxt*/&xbb->io_taskqueue);
3850 if (xbb->io_taskqueue == NULL) {
3851 xbb_attach_failed(xbb, error, "Unable to create taskqueue");
3855 taskqueue_start_threads(&xbb->io_taskqueue,
3859 "%s taskq", device_get_nameunit(dev));
3861 /* Update hot-plug status to satisfy xend. */
3862 error = xs_printf(XST_NIL, xenbus_get_node(xbb->dev),
3863 "hotplug-status", "connected");
3865 xbb_attach_failed(xbb, error, "writing %s/hotplug-status",
3866 xenbus_get_node(xbb->dev));
3870 /* Tell the front end that we are ready to connect. */
3871 xenbus_set_state(dev, XenbusStateInitWait);
3877 * Detach from a block back device instance.
3879 * \param dev NewBus device object representing this Xen Block Back instance.
3881 * \return 0 for success, errno codes for failure.
3883 * \note A block back device may be detached at any time in its life-cycle,
3884 * including part way through the attach process. For this reason,
3885 * initialization order and the intialization state checks in this
3886 * routine must be carefully coupled so that attach time failures
3887 * are gracefully handled.
3890 xbb_detach(device_t dev)
3892 struct xbb_softc *xbb;
3896 xbb = device_get_softc(dev);
3897 mtx_lock(&xbb->lock);
3898 while (xbb_shutdown(xbb) == EAGAIN) {
3899 msleep(xbb, &xbb->lock, /*wakeup prio unchanged*/0,
3902 mtx_unlock(&xbb->lock);
3906 if (xbb->io_taskqueue != NULL)
3907 taskqueue_free(xbb->io_taskqueue);
3909 if (xbb->xbb_stats != NULL)
3910 devstat_remove_entry(xbb->xbb_stats);
3912 if (xbb->xbb_stats_in != NULL)
3913 devstat_remove_entry(xbb->xbb_stats_in);
3915 xbb_close_backend(xbb);
3917 if (xbb->dev_mode != NULL) {
3918 free(xbb->dev_mode, M_XENSTORE);
3919 xbb->dev_mode = NULL;
3922 if (xbb->dev_type != NULL) {
3923 free(xbb->dev_type, M_XENSTORE);
3924 xbb->dev_type = NULL;
3927 if (xbb->dev_name != NULL) {
3928 free(xbb->dev_name, M_XENSTORE);
3929 xbb->dev_name = NULL;
3932 mtx_destroy(&xbb->lock);
3937 * Prepare this block back device for suspension of this VM.
3939 * \param dev NewBus device object representing this Xen Block Back instance.
3941 * \return 0 for success, errno codes for failure.
3944 xbb_suspend(device_t dev)
3947 struct xbb_softc *sc = device_get_softc(dev);
3949 /* Prevent new requests being issued until we fix things up. */
3950 mtx_lock(&sc->xb_io_lock);
3951 sc->connected = BLKIF_STATE_SUSPENDED;
3952 mtx_unlock(&sc->xb_io_lock);
3959 * Perform any processing required to recover from a suspended state.
3961 * \param dev NewBus device object representing this Xen Block Back instance.
3963 * \return 0 for success, errno codes for failure.
3966 xbb_resume(device_t dev)
3972 * Handle state changes expressed via the XenStore by our front-end peer.
3974 * \param dev NewBus device object representing this Xen
3975 * Block Back instance.
3976 * \param frontend_state The new state of the front-end.
3978 * \return 0 for success, errno codes for failure.
3981 xbb_frontend_changed(device_t dev, XenbusState frontend_state)
3983 struct xbb_softc *xbb = device_get_softc(dev);
3985 DPRINTF("frontend_state=%s, xbb_state=%s\n",
3986 xenbus_strstate(frontend_state),
3987 xenbus_strstate(xenbus_get_state(xbb->dev)));
3989 switch (frontend_state) {
3990 case XenbusStateInitialising:
3992 case XenbusStateInitialised:
3993 case XenbusStateConnected:
3996 case XenbusStateClosing:
3997 case XenbusStateClosed:
3998 mtx_lock(&xbb->lock);
4000 mtx_unlock(&xbb->lock);
4001 if (frontend_state == XenbusStateClosed)
4002 xenbus_set_state(xbb->dev, XenbusStateClosed);
4005 xenbus_dev_fatal(xbb->dev, EINVAL, "saw state %d at frontend",
4011 /*---------------------------- NewBus Registration ---------------------------*/
4012 static device_method_t xbb_methods[] = {
4013 /* Device interface */
4014 DEVMETHOD(device_probe, xbb_probe),
4015 DEVMETHOD(device_attach, xbb_attach),
4016 DEVMETHOD(device_detach, xbb_detach),
4017 DEVMETHOD(device_shutdown, bus_generic_shutdown),
4018 DEVMETHOD(device_suspend, xbb_suspend),
4019 DEVMETHOD(device_resume, xbb_resume),
4021 /* Xenbus interface */
4022 DEVMETHOD(xenbus_otherend_changed, xbb_frontend_changed),
4027 static driver_t xbb_driver = {
4030 sizeof(struct xbb_softc),
4032 devclass_t xbb_devclass;
4034 DRIVER_MODULE(xbbd, xenbusb_back, xbb_driver, xbb_devclass, 0, 0);