[PATCH V2 01/12] Drivers: hv: vss: run only on supported host versions

From: K. Y. Srinivasan
Date: Wed Nov 11 2015 - 19:57:52 EST

From: Olaf Hering <olaf@xxxxxxxxx>

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.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
drivers/hv/hv_snapshot.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c
index a548ae4..81882d4 100644
--- a/drivers/hv/hv_snapshot.c
+++ b/drivers/hv/hv_snapshot.c
@@ -331,6 +331,11 @@ static void vss_on_reset(void)
hv_vss_init(struct hv_util_service *srv)
+ if (vmbus_proto_version < VERSION_WIN8_1) {
+ pr_warn("Integration service 'Backup (volume snapshot)'"
+ " not supported on this host version.\n");
+ return -ENOTSUPP;
+ }
recv_buffer = srv->recv_buffer;


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