From 75c2786c25fef9a6f8239c9fc1631cd17756579b Mon Sep 17 00:00:00 2001
From: Wei Hu <whu@FreeBSD.org>
Date: Thu, 15 Oct 2020 05:57:20 +0000
Subject: [PATCH] Hyper-V: pcib: Check revoke status during device attach

It is possible that the vmbus pcib channel is revoked during attach path.
The attach path could be waiting for response from host and this response will never
arrive since the channel has already been revoked from host point of view. Check
this situation during wait complete and return failed if this happens.

Reported by:	Netapp
MFC after:	2 weeks
Sponsored by:	Microsoft
Differential Revision:	https://reviews.freebsd.org/D26486
---
 sys/dev/hyperv/pcib/vmbus_pcib.c | 78 +++++++++++++++++++++++++++-----
 1 file changed, 66 insertions(+), 12 deletions(-)

diff --git a/sys/dev/hyperv/pcib/vmbus_pcib.c b/sys/dev/hyperv/pcib/vmbus_pcib.c
index 0d49ae313cc..72e430c946d 100644
--- a/sys/dev/hyperv/pcib/vmbus_pcib.c
+++ b/sys/dev/hyperv/pcib/vmbus_pcib.c
@@ -117,6 +117,31 @@ wait_for_completion(struct completion *c)
 	mtx_unlock(&c->lock);
 }
 
+/*
+ * Return: 0 if completed, a non-zero value if timed out.
+ */
+static int
+wait_for_completion_timeout(struct completion *c, int timeout)
+{
+	int ret;
+
+	mtx_lock(&c->lock);
+
+	if (c->done == 0)
+		mtx_sleep(c, &c->lock, 0, "hvwfc", timeout);
+
+	if (c->done > 0) {
+		c->done--;
+		ret = 0;
+	} else {
+		ret = 1;
+	}
+
+	mtx_unlock(&c->lock);
+
+	return (ret);
+}
+
 #define PCI_MAKE_VERSION(major, minor) ((uint32_t)(((major) << 16) | (major)))
 
 enum {
@@ -438,6 +463,25 @@ struct compose_comp_ctxt {
 	struct tran_int_desc int_desc;
 };
 
+/*
+ * It is possible the device is revoked during initialization.
+ * Check if this happens during wait.
+ * Return: 0 if response arrived, ENODEV if device revoked.
+ */
+static int
+wait_for_response(struct hv_pcibus *hbus, struct completion *c)
+{
+	do {
+		if (vmbus_chan_is_revoked(hbus->sc->chan)) {
+			device_printf(hbus->pcib,
+			    "The device is revoked.\n");
+			return (ENODEV);
+		}
+	} while (wait_for_completion_timeout(c, hz /10) != 0);
+
+	return 0;
+}
+
 static void
 hv_pci_generic_compl(void *context, struct pci_response *resp,
     int resp_packet_size)
@@ -568,7 +612,9 @@ new_pcichild_device(struct hv_pcibus *hbus, struct pci_func_desc *desc)
 	if (ret)
 		goto err;
 
-	wait_for_completion(&comp_pkt.host_event);
+	if (wait_for_response(hbus, &comp_pkt.host_event))
+		goto err;
+
 	free_completion(&comp_pkt.host_event);
 
 	hpdev->desc = *desc;
@@ -1011,10 +1057,15 @@ hv_pci_protocol_negotiation(struct hv_pcibus *hbus)
 	ret = vmbus_chan_send(hbus->sc->chan, VMBUS_CHANPKT_TYPE_INBAND,
 	    VMBUS_CHANPKT_FLAG_RC, version_req, sizeof(*version_req),
 	    (uint64_t)(uintptr_t)&ctxt.pkt);
-	if (ret)
-		goto out;
+	if (!ret)
+		ret = wait_for_response(hbus, &comp_pkt.host_event);
 
-	wait_for_completion(&comp_pkt.host_event);
+	if (ret) {
+		device_printf(hbus->pcib,
+		    "vmbus_pcib failed to request version: %d\n",
+		    ret);
+		goto out;
+	}
 
 	if (comp_pkt.completion_status < 0) {
 		device_printf(hbus->pcib,
@@ -1072,11 +1123,12 @@ hv_pci_enter_d0(struct hv_pcibus *hbus)
 	ret = vmbus_chan_send(hbus->sc->chan, VMBUS_CHANPKT_TYPE_INBAND,
 	    VMBUS_CHANPKT_FLAG_RC, d0_entry, sizeof(*d0_entry),
 	    (uint64_t)(uintptr_t)&ctxt.pkt);
+	if (!ret)
+		ret = wait_for_response(hbus, &comp_pkt.host_event);
+
 	if (ret)
 		goto out;
 
-	wait_for_completion(&comp_pkt.host_event);
-
 	if (comp_pkt.completion_status < 0) {
 		device_printf(hbus->pcib, "vmbus_pcib failed to enable D0\n");
 		ret = EPROTO;
@@ -1125,14 +1177,14 @@ hv_send_resources_allocated(struct hv_pcibus *hbus)
 		    VMBUS_CHANPKT_TYPE_INBAND, VMBUS_CHANPKT_FLAG_RC,
 		    &pkt->message, sizeof(*res_assigned),
 		    (uint64_t)(uintptr_t)pkt);
-		if (ret) {
-			free_completion(&comp_pkt.host_event);
-			break;
-		}
+		if (!ret)
+			ret = wait_for_response(hbus, &comp_pkt.host_event);
 
-		wait_for_completion(&comp_pkt.host_event);
 		free_completion(&comp_pkt.host_event);
 
+		if (ret)
+			break;
+
 		if (comp_pkt.completion_status < 0) {
 			ret = EPROTO;
 			device_printf(hbus->pcib,
@@ -1413,9 +1465,11 @@ vmbus_pcib_attach(device_t dev)
 		goto vmbus_close;
 
 	ret = hv_pci_query_relations(hbus);
+	if (!ret)
+		ret = wait_for_response(hbus, hbus->query_comp);
+
 	if (ret)
 		goto vmbus_close;
-	wait_for_completion(hbus->query_comp);
 
 	ret = hv_pci_enter_d0(hbus);
 	if (ret)
-- 
2.45.2