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Drivers: hv: vss: run only on supported host versions

PATCH Superseded Olaf Hering 2 participants 2 messages Oct 13, 2015 – Oct 19, 2015 Hyper-V/Azure core and drivers

v1 of 2 Superseded Latest is v2 →

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#0 lore raw

PATCH 1/1 Drivers: hv: vss: run only on supported host versions

The Backup integration service on WS2012 has appearently trouble to negotiate with a guest which does not support the provided util version. Currently the VSS driver supports only version 5/0. A WS2012 offers only version 1/x and 3/x, and vmbus_prep_negotiate_resp correctly returns an empty icframe_vercnt/icmsg_vercnt. But the host ignores that and continues to send ICMSGTYPE_NEGOTIATE messages. The result are weird errors during boot and general misbehaviour.

Check the Windows version to work around the host bug, skip hv_vss_init on WS2012 and older.

---
 drivers/hv/hv_snapshot.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
drivers/hv/hv_snapshot.c +10 -0
index a548ae4..52f10ed 100644
@@ -331,6 +331,16 @@ static void vss_on_reset(void)
 int
 hv_vss_init(struct hv_util_service *srv)
 {
+	switch (vmbus_proto_version) {
+		case VERSION_WS2008:
+		case VERSION_WIN7:
+		case VERSION_WIN8:
+			pr_warn("Integration service 'Backup (volume snapshot)'"
+				" not supported on this host version.\n");
+			return -ENOTSUPP;
+		default:
+			break;
+	}
 	recv_buffer = srv->recv_buffer;
 
 	/*
#1 lore raw
Quoted 21 lines · Olaf Hering

The Backup integration service on WS2012 has appearently trouble to negotiate with a guest which does not support the provided util version. Currently the VSS driver supports only version 5/0. A WS2012 offers only version 1/x and 3/x, and vmbus_prep_negotiate_resp correctly returns an empty icframe_vercnt/icmsg_vercnt. But the host ignores that and continues to send ICMSGTYPE_NEGOTIATE messages. The result are weird errors during boot and general misbehaviour.

Check the Windows version to work around the host bug, skip hv_vss_init on WS2012 and older.

---
 drivers/hv/hv_snapshot.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
drivers/hv/hv_snapshot.c +0 -0
index a548ae4..52f10ed 100644

drivers/hv/hv_snapshot.c static void vss_on_reset(void) · line 337

Quoted 7 lines
drivers/hv/hv_snapshot.c +4 -0
@@ -331,6 +331,16 @@ static void vss_on_reset(void)
 int
 hv_vss_init(struct hv_util_service *srv)
 {
+	switch (vmbus_proto_version) {
+		case VERSION_WS2008:
+		case VERSION_WIN7:
+		case VERSION_WIN8:

Wouldn't it be better to simplify it to

    if (vmbus_proto_version < VERSION_WIN8_1) {
        pr_warn();
        return ...
    }

E.g. there was a patch for storvsc some time ago:

commit 6ee5c61535a2df807069145970d3e7fa492a3fac

Author: Keith Mange <[email protected]>
Date:   Thu Aug 13 08:43:46 2015 -0700

storvsc: Rather than look for sets of specific protocol versions, make decisions based on ranges.

Quoted 13 lines
drivers/hv/hv_snapshot.c +6 -0
+			pr_warn("Integration service 'Backup (volume snapshot)'"
+				" not supported on this host version.\n");
+			return -ENOTSUPP;
+		default:
+			break;
+	}
 	recv_buffer = srv->recv_buffer;
 
 	/*

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