From: Vitaly Kuznetsov vkuznets@redhat.com
[ Upstream commit 9d68cd9120e4e3af38f843e165631c323b86b4e4 ]
Commit adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer") introduced a notion of maximum packet size and for KVM and FCOPY drivers set it to the length of the receive buffer. VSS driver wasn't updated, this means that the maximum packet size is now VMBUS_DEFAULT_MAX_PKT_SIZE (4k). Apparently, this is not enough. I'm observing a packet of 6304 bytes which is being truncated to 4096. When VSS driver tries to read next packet from ring buffer it starts from the wrong offset and receives garbage.
Set the maximum packet size to 'HV_HYP_PAGE_SIZE * 2' in VSS driver. This matches the length of the receive buffer and is in line with other utils drivers.
Fixes: adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer") Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com Reviewed-by: Michael Kelley mikelley@microsoft.com Link: https://lore.kernel.org/r/20210825133857.847866-1-vkuznets@redhat.com Signed-off-by: Wei Liu wei.liu@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/hv/hv_snapshot.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/hv/hv_snapshot.c b/drivers/hv/hv_snapshot.c index 2267bd4c3472..6018b9d1b1fb 100644 --- a/drivers/hv/hv_snapshot.c +++ b/drivers/hv/hv_snapshot.c @@ -375,6 +375,7 @@ hv_vss_init(struct hv_util_service *srv) } recv_buffer = srv->recv_buffer; vss_transaction.recv_channel = srv->channel; + vss_transaction.recv_channel->max_pkt_size = HV_HYP_PAGE_SIZE * 2;
/* * When this driver loads, the user level daemon that