2 * Copyright (c) 2003 Peter Wemm.
3 * Copyright (c) 1992 Terrence R. Lambert.
4 * Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
7 * This code is derived from software contributed to Berkeley by
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * from: @(#)machdep.c 7.4 (Berkeley) 6/3/91
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
44 #include "opt_atpic.h"
45 #include "opt_compat.h"
51 #include "opt_kstack_pages.h"
52 #include "opt_maxmem.h"
53 #include "opt_mp_watchdog.h"
54 #include "opt_perfmon.h"
55 #include "opt_platform.h"
61 #include <sys/param.h>
63 #include <sys/systm.h>
67 #include <sys/kernel.h>
70 #include <sys/malloc.h>
71 #include <sys/mutex.h>
73 #include <sys/rwlock.h>
74 #include <sys/sched.h>
78 #include <sys/sysctl.h>
80 #include <machine/clock.h>
81 #include <machine/cpu.h>
82 #include <machine/cputypes.h>
83 #include <machine/specialreg.h>
84 #include <machine/md_var.h>
85 #include <machine/mp_watchdog.h>
87 #include <machine/perfmon.h>
89 #include <machine/tss.h>
91 #include <machine/smp.h>
94 #include <machine/elan_mmcr.h>
96 #include <x86/acpica_machdep.h>
99 #include <vm/vm_extern.h>
100 #include <vm/vm_kern.h>
101 #include <vm/vm_page.h>
102 #include <vm/vm_map.h>
103 #include <vm/vm_object.h>
104 #include <vm/vm_pager.h>
105 #include <vm/vm_param.h>
108 #include <isa/isareg.h>
111 #define STATE_RUNNING 0x0
112 #define STATE_MWAIT 0x1
113 #define STATE_SLEEPING 0x2
116 static u_int cpu_reset_proxyid;
117 static volatile u_int cpu_reset_proxy_active;
122 * Machine dependent boot() routine
124 * I haven't seen anything to put here yet
125 * Possibly some stuff might be grafted back here from boot()
133 * Flush the D-cache for non-DMA I/O so that the I-cache can
134 * be made coherent later.
137 cpu_flush_dcache(void *ptr, size_t len)
146 __asm __volatile("sti; hlt");
150 * Use mwait to pause execution while waiting for an interrupt or
151 * another thread to signal that there is more work.
153 * NOTE: Interrupts will cause a wakeup; however, this function does
154 * not enable interrupt handling. The caller is responsible to enable
158 acpi_cpu_idle_mwait(uint32_t mwait_hint)
164 * A comment in Linux patch claims that 'CPUs run faster with
165 * speculation protection disabled. All CPU threads in a core
166 * must disable speculation protection for it to be
167 * disabled. Disable it while we are idle so the other
168 * hyperthread can run fast.'
170 * XXXKIB. Software coordination mode should be supported,
171 * but all Intel CPUs provide hardware coordination.
174 state = (int *)PCPU_PTR(monitorbuf);
175 KASSERT(atomic_load_int(state) == STATE_SLEEPING,
176 ("cpu_mwait_cx: wrong monitorbuf state"));
177 atomic_store_int(state, STATE_MWAIT);
178 if (PCPU_GET(ibpb_set) || hw_ssb_active) {
179 v = rdmsr(MSR_IA32_SPEC_CTRL);
180 wrmsr(MSR_IA32_SPEC_CTRL, v & ~(IA32_SPEC_CTRL_IBRS |
181 IA32_SPEC_CTRL_STIBP | IA32_SPEC_CTRL_SSBD));
185 cpu_monitor(state, 0, 0);
186 if (atomic_load_int(state) == STATE_MWAIT)
187 cpu_mwait(MWAIT_INTRBREAK, mwait_hint);
190 * SSB cannot be disabled while we sleep, or rather, if it was
191 * disabled, the sysctl thread will bind to our cpu to tweak
195 wrmsr(MSR_IA32_SPEC_CTRL, v);
198 * We should exit on any event that interrupts mwait, because
199 * that event might be a wanted interrupt.
201 atomic_store_int(state, STATE_RUNNING);
204 /* Get current clock frequency for the given cpu id. */
206 cpu_est_clockrate(int cpu_id, uint64_t *rate)
209 uint64_t acnt, mcnt, perf;
212 if (pcpu_find(cpu_id) == NULL || rate == NULL)
215 if ((cpu_feature & CPUID_TSC) == 0)
220 * If TSC is P-state invariant and APERF/MPERF MSRs do not exist,
221 * DELAY(9) based logic fails.
223 if (tsc_is_invariant && !tsc_perf_stat)
228 /* Schedule ourselves on the indicated cpu. */
229 thread_lock(curthread);
230 sched_bind(curthread, cpu_id);
231 thread_unlock(curthread);
235 /* Calibrate by measuring a short delay. */
236 reg = intr_disable();
237 if (tsc_is_invariant) {
242 mcnt = rdmsr(MSR_MPERF);
243 acnt = rdmsr(MSR_APERF);
246 perf = 1000 * acnt / mcnt;
247 *rate = (tsc2 - tsc1) * perf;
253 *rate = (tsc2 - tsc1) * 1000;
258 thread_lock(curthread);
259 sched_unbind(curthread);
260 thread_unlock(curthread);
268 * Shutdown the CPU as much as possible
280 struct region_descriptor null_idt;
287 if (elan_mmcr != NULL)
288 elan_mmcr->RESCFG = 1;
291 if (cpu == CPU_GEODE1100) {
292 /* Attempt Geode's own reset */
293 outl(0xcf8, 0x80009044ul);
299 * Attempt to do a CPU reset via CPU reset port.
301 if ((inb(0x35) & 0xa0) != 0xa0) {
302 outb(0x37, 0x0f); /* SHUT0 = 0. */
303 outb(0x37, 0x0b); /* SHUT1 = 0. */
305 outb(0xf0, 0x00); /* Reset. */
307 #if !defined(BROKEN_KEYBOARD_RESET)
309 * Attempt to do a CPU reset via the keyboard controller,
310 * do not turn off GateA20, as any machine that fails
311 * to do the reset here would then end up in no man's land.
313 outb(IO_KBD + 4, 0xFE);
314 DELAY(500000); /* wait 0.5 sec to see if that did it */
318 * Attempt to force a reset via the Reset Control register at
319 * I/O port 0xcf9. Bit 2 forces a system reset when it
320 * transitions from 0 to 1. Bit 1 selects the type of reset
321 * to attempt: 0 selects a "soft" reset, and 1 selects a
322 * "hard" reset. We try a "hard" reset. The first write sets
323 * bit 1 to select a "hard" reset and clears bit 2. The
324 * second write forces a 0 -> 1 transition in bit 2 to trigger
329 DELAY(500000); /* wait 0.5 sec to see if that did it */
332 * Attempt to force a reset via the Fast A20 and Init register
333 * at I/O port 0x92. Bit 1 serves as an alternate A20 gate.
334 * Bit 0 asserts INIT# when set to 1. We are careful to only
335 * preserve bit 1 while setting bit 0. We also must clear bit
336 * 0 before setting it if it isn't already clear.
341 outb(0x92, b & 0xfe);
343 DELAY(500000); /* wait 0.5 sec to see if that did it */
347 printf("No known reset method worked, attempting CPU shutdown\n");
348 DELAY(1000000); /* wait 1 sec for printf to complete */
351 null_idt.rd_limit = 0;
352 null_idt.rd_base = 0;
355 /* "good night, sweet prince .... <THUNK!>" */
364 cpu_reset_proxy(void)
367 cpu_reset_proxy_active = 1;
368 while (cpu_reset_proxy_active == 1)
369 ia32_pause(); /* Wait for other cpu to see that we've started */
371 printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
386 CPU_CLR(PCPU_GET(cpuid), &map);
387 CPU_NAND(&map, &stopped_cpus);
388 if (!CPU_EMPTY(&map)) {
389 printf("cpu_reset: Stopping other CPUs\n");
393 if (PCPU_GET(cpuid) != 0) {
394 cpu_reset_proxyid = PCPU_GET(cpuid);
395 cpustop_restartfunc = cpu_reset_proxy;
396 cpu_reset_proxy_active = 0;
397 printf("cpu_reset: Restarting BSP\n");
399 /* Restart CPU #0. */
400 CPU_SETOF(0, &started_cpus);
404 while (cpu_reset_proxy_active == 0 && cnt < 10000000) {
406 cnt++; /* Wait for BSP to announce restart */
408 if (cpu_reset_proxy_active == 0) {
409 printf("cpu_reset: Failed to restart BSP\n");
411 cpu_reset_proxy_active = 2;
426 cpu_mwait_usable(void)
429 return ((cpu_feature2 & CPUID2_MON) != 0 && ((cpu_mon_mwait_flags &
430 (CPUID5_MON_MWAIT_EXT | CPUID5_MWAIT_INTRBREAK)) ==
431 (CPUID5_MON_MWAIT_EXT | CPUID5_MWAIT_INTRBREAK)));
434 void (*cpu_idle_hook)(sbintime_t) = NULL; /* ACPI idle hook. */
435 static int cpu_ident_amdc1e = 0; /* AMD C1E supported. */
436 static int idle_mwait = 1; /* Use MONITOR/MWAIT for short idle. */
437 SYSCTL_INT(_machdep, OID_AUTO, idle_mwait, CTLFLAG_RWTUN, &idle_mwait,
438 0, "Use MONITOR/MWAIT for short idle");
442 cpu_idle_acpi(sbintime_t sbt)
446 state = (int *)PCPU_PTR(monitorbuf);
447 atomic_store_int(state, STATE_SLEEPING);
449 /* See comments in cpu_idle_hlt(). */
451 if (sched_runnable())
453 else if (cpu_idle_hook)
457 atomic_store_int(state, STATE_RUNNING);
462 cpu_idle_hlt(sbintime_t sbt)
466 state = (int *)PCPU_PTR(monitorbuf);
467 atomic_store_int(state, STATE_SLEEPING);
470 * Since we may be in a critical section from cpu_idle(), if
471 * an interrupt fires during that critical section we may have
472 * a pending preemption. If the CPU halts, then that thread
473 * may not execute until a later interrupt awakens the CPU.
474 * To handle this race, check for a runnable thread after
475 * disabling interrupts and immediately return if one is
476 * found. Also, we must absolutely guarentee that hlt is
477 * the next instruction after sti. This ensures that any
478 * interrupt that fires after the call to disable_intr() will
479 * immediately awaken the CPU from hlt. Finally, please note
480 * that on x86 this works fine because of interrupts enabled only
481 * after the instruction following sti takes place, while IF is set
482 * to 1 immediately, allowing hlt instruction to acknowledge the
486 if (sched_runnable())
490 atomic_store_int(state, STATE_RUNNING);
494 cpu_idle_mwait(sbintime_t sbt)
498 state = (int *)PCPU_PTR(monitorbuf);
499 atomic_store_int(state, STATE_MWAIT);
501 /* See comments in cpu_idle_hlt(). */
503 if (sched_runnable()) {
504 atomic_store_int(state, STATE_RUNNING);
509 cpu_monitor(state, 0, 0);
510 if (atomic_load_int(state) == STATE_MWAIT)
511 __asm __volatile("sti; mwait" : : "a" (MWAIT_C1), "c" (0));
514 atomic_store_int(state, STATE_RUNNING);
518 cpu_idle_spin(sbintime_t sbt)
523 state = (int *)PCPU_PTR(monitorbuf);
524 atomic_store_int(state, STATE_RUNNING);
527 * The sched_runnable() call is racy but as long as there is
528 * a loop missing it one time will have just a little impact if any
529 * (and it is much better than missing the check at all).
531 for (i = 0; i < 1000; i++) {
532 if (sched_runnable())
539 * C1E renders the local APIC timer dead, so we disable it by
540 * reading the Interrupt Pending Message register and clearing
541 * both C1eOnCmpHalt (bit 28) and SmiOnCmpHalt (bit 27).
544 * "BIOS and Kernel Developer's Guide for AMD NPT Family 0Fh Processors"
545 * #32559 revision 3.00+
547 #define MSR_AMDK8_IPM 0xc0010055
548 #define AMDK8_SMIONCMPHALT (1ULL << 27)
549 #define AMDK8_C1EONCMPHALT (1ULL << 28)
550 #define AMDK8_CMPHALT (AMDK8_SMIONCMPHALT | AMDK8_C1EONCMPHALT)
553 cpu_probe_amdc1e(void)
557 * Detect the presence of C1E capability mostly on latest
558 * dual-cores (or future) k8 family.
560 if (cpu_vendor_id == CPU_VENDOR_AMD &&
561 (cpu_id & 0x00000f00) == 0x00000f00 &&
562 (cpu_id & 0x0fff0000) >= 0x00040000) {
563 cpu_ident_amdc1e = 1;
567 #if defined(__i386__) && defined(PC98)
568 void (*cpu_idle_fn)(sbintime_t) = cpu_idle_hlt;
570 void (*cpu_idle_fn)(sbintime_t) = cpu_idle_acpi;
579 CTR2(KTR_SPARE2, "cpu_idle(%d) at %d",
582 ap_watchdog(PCPU_GET(cpuid));
585 /* If we are busy - try to use fast methods. */
587 if ((cpu_feature2 & CPUID2_MON) && idle_mwait) {
588 cpu_idle_mwait(busy);
593 /* If we have time - switch timers into idle mode. */
596 sbt = cpu_idleclock();
599 /* Apply AMD APIC timer C1E workaround. */
600 if (cpu_ident_amdc1e && cpu_disable_c3_sleep) {
601 msr = rdmsr(MSR_AMDK8_IPM);
602 if (msr & AMDK8_CMPHALT)
603 wrmsr(MSR_AMDK8_IPM, msr & ~AMDK8_CMPHALT);
606 /* Call main idle method. */
609 /* Switch timers back into active mode. */
615 CTR2(KTR_SPARE2, "cpu_idle(%d) at %d done",
619 static int cpu_idle_apl31_workaround;
620 SYSCTL_INT(_machdep, OID_AUTO, idle_apl31, CTLFLAG_RW,
621 &cpu_idle_apl31_workaround, 0,
622 "Apollo Lake APL31 MWAIT bug workaround");
625 cpu_idle_wakeup(int cpu)
629 state = (int *)pcpu_find(cpu)->pc_monitorbuf;
630 switch (atomic_load_int(state)) {
634 atomic_store_int(state, STATE_RUNNING);
635 return (cpu_idle_apl31_workaround ? 0 : 1);
639 panic("bad monitor state");
645 * Ordered by speed/power consumption.
652 { .id_fn = cpu_idle_spin, .id_name = "spin" },
653 { .id_fn = cpu_idle_mwait, .id_name = "mwait",
654 .id_cpuid2_flag = CPUID2_MON },
655 { .id_fn = cpu_idle_hlt, .id_name = "hlt" },
656 #if !defined(__i386__) || !defined(PC98)
657 { .id_fn = cpu_idle_acpi, .id_name = "acpi" },
662 idle_sysctl_available(SYSCTL_HANDLER_ARGS)
668 avail = malloc(256, M_TEMP, M_WAITOK);
670 for (i = 0; i < nitems(idle_tbl); i++) {
671 if (idle_tbl[i].id_cpuid2_flag != 0 &&
672 (cpu_feature2 & idle_tbl[i].id_cpuid2_flag) == 0)
674 #if !defined(__i386__) || !defined(PC98)
675 if (strcmp(idle_tbl[i].id_name, "acpi") == 0 &&
676 cpu_idle_hook == NULL)
679 p += sprintf(p, "%s%s", p != avail ? ", " : "",
680 idle_tbl[i].id_name);
682 error = sysctl_handle_string(oidp, avail, 0, req);
687 SYSCTL_PROC(_machdep, OID_AUTO, idle_available, CTLTYPE_STRING | CTLFLAG_RD,
688 0, 0, idle_sysctl_available, "A", "list of available idle functions");
691 cpu_idle_selector(const char *new_idle_name)
695 for (i = 0; i < nitems(idle_tbl); i++) {
696 if (idle_tbl[i].id_cpuid2_flag != 0 &&
697 (cpu_feature2 & idle_tbl[i].id_cpuid2_flag) == 0)
699 #if !defined(__i386__) || !defined(PC98)
700 if (strcmp(idle_tbl[i].id_name, "acpi") == 0 &&
701 cpu_idle_hook == NULL)
704 if (strcmp(idle_tbl[i].id_name, new_idle_name))
706 cpu_idle_fn = idle_tbl[i].id_fn;
708 printf("CPU idle set to %s\n", idle_tbl[i].id_name);
715 cpu_idle_sysctl(SYSCTL_HANDLER_ARGS)
721 for (i = 0; i < nitems(idle_tbl); i++) {
722 if (idle_tbl[i].id_fn == cpu_idle_fn) {
723 p = idle_tbl[i].id_name;
727 strncpy(buf, p, sizeof(buf));
728 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
729 if (error != 0 || req->newptr == NULL)
731 return (cpu_idle_selector(buf) ? 0 : EINVAL);
734 SYSCTL_PROC(_machdep, OID_AUTO, idle, CTLTYPE_STRING | CTLFLAG_RW, 0, 0,
735 cpu_idle_sysctl, "A", "currently selected idle function");
738 cpu_idle_tun(void *unused __unused)
742 if (TUNABLE_STR_FETCH("machdep.idle", tunvar, sizeof(tunvar)))
743 cpu_idle_selector(tunvar);
744 if (cpu_vendor_id == CPU_VENDOR_INTEL && cpu_id == 0x506c9) {
746 * Apollo Lake errata APL31 (public errata APL30).
747 * Stores to the armed address range may not trigger
748 * MWAIT to resume execution. OS needs to use
749 * interrupts to wake processors from MWAIT-induced
752 cpu_idle_apl31_workaround = 1;
754 TUNABLE_INT_FETCH("machdep.idle_apl31", &cpu_idle_apl31_workaround);
756 SYSINIT(cpu_idle_tun, SI_SUB_CPU, SI_ORDER_MIDDLE, cpu_idle_tun, NULL);
758 static int panic_on_nmi = 1;
759 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RWTUN,
762 int nmi_is_broadcast = 1;
763 SYSCTL_INT(_machdep, OID_AUTO, nmi_is_broadcast, CTLFLAG_RWTUN,
764 &nmi_is_broadcast, 0,
765 "Chipset NMI is broadcast");
768 SYSCTL_INT(_machdep, OID_AUTO, kdb_on_nmi, CTLFLAG_RWTUN,
775 nmi_call_kdb(u_int cpu, u_int type, struct trapframe *frame)
778 /* machine/parity/power fail/"kitchen sink" faults */
779 if (isa_nmi(frame->tf_err) == 0) {
782 * NMI can be hooked up to a pushbutton for debugging.
785 printf("NMI/cpu%d ... going to debugger\n", cpu);
786 kdb_trap(type, 0, frame);
789 } else if (panic_on_nmi) {
790 panic("NMI indicates hardware failure");
796 nmi_handle_intr(u_int type, struct trapframe *frame)
801 if (nmi_is_broadcast) {
802 nmi_call_kdb_smp(type, frame);
806 nmi_call_kdb(PCPU_GET(cpuid), type, frame);
811 int hw_ibrs_disable = 1;
813 SYSCTL_INT(_hw, OID_AUTO, ibrs_active, CTLFLAG_RD, &hw_ibrs_active, 0,
814 "Indirect Branch Restricted Speculation active");
817 hw_ibrs_recalculate(void)
821 if ((cpu_ia32_arch_caps & IA32_ARCH_CAP_IBRS_ALL) != 0) {
822 if (hw_ibrs_disable) {
823 v = rdmsr(MSR_IA32_SPEC_CTRL);
824 v &= ~(uint64_t)IA32_SPEC_CTRL_IBRS;
825 wrmsr(MSR_IA32_SPEC_CTRL, v);
827 v = rdmsr(MSR_IA32_SPEC_CTRL);
828 v |= IA32_SPEC_CTRL_IBRS;
829 wrmsr(MSR_IA32_SPEC_CTRL, v);
833 hw_ibrs_active = (cpu_stdext_feature3 & CPUID_STDEXT3_IBPB) != 0 &&
838 hw_ibrs_disable_handler(SYSCTL_HANDLER_ARGS)
842 val = hw_ibrs_disable;
843 error = sysctl_handle_int(oidp, &val, 0, req);
844 if (error != 0 || req->newptr == NULL)
846 hw_ibrs_disable = val != 0;
847 hw_ibrs_recalculate();
850 SYSCTL_PROC(_hw, OID_AUTO, ibrs_disable, CTLTYPE_INT | CTLFLAG_RWTUN |
851 CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0, hw_ibrs_disable_handler, "I",
852 "Disable Indirect Branch Restricted Speculation");
857 SYSCTL_INT(_hw, OID_AUTO, spec_store_bypass_disable_active, CTLFLAG_RD,
859 "Speculative Store Bypass Disable active");
862 hw_ssb_set_one(bool enable)
866 v = rdmsr(MSR_IA32_SPEC_CTRL);
868 v |= (uint64_t)IA32_SPEC_CTRL_SSBD;
870 v &= ~(uint64_t)IA32_SPEC_CTRL_SSBD;
871 wrmsr(MSR_IA32_SPEC_CTRL, v);
875 hw_ssb_set(bool enable, bool for_all_cpus)
878 int bound_cpu, i, is_bound;
880 if ((cpu_stdext_feature3 & CPUID_STDEXT3_SSBD) == 0) {
884 hw_ssb_active = enable;
888 is_bound = sched_is_bound(td);
889 bound_cpu = td->td_oncpu;
892 hw_ssb_set_one(enable);
895 sched_bind(td, bound_cpu);
900 hw_ssb_set_one(enable);
905 hw_ssb_recalculate(bool all_cpus)
908 switch (hw_ssb_disable) {
913 hw_ssb_set(false, all_cpus);
916 hw_ssb_set(true, all_cpus);
919 hw_ssb_set((cpu_ia32_arch_caps & IA32_ARCH_CAP_SSBD_NO) != 0 ?
920 false : true, all_cpus);
926 hw_ssb_disable_handler(SYSCTL_HANDLER_ARGS)
930 val = hw_ssb_disable;
931 error = sysctl_handle_int(oidp, &val, 0, req);
932 if (error != 0 || req->newptr == NULL)
934 hw_ssb_disable = val;
935 hw_ssb_recalculate(true);
938 SYSCTL_PROC(_hw, OID_AUTO, spec_store_bypass_disable, CTLTYPE_INT |
939 CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
940 hw_ssb_disable_handler, "I",
941 "Speculative Store Bypass Disable (0 - off, 1 - on, 2 - auto");