This is a note to let you know that I've just added the patch titled Drivers: hv: vmbus: Fix handling of messages with transaction ID of zero to the 5.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drivers-hv-vmbus-fix-handling-of-messages-with-trans.patch and it can be found in the queue-5.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit d91a8e2ec450a10e8ac82faf3a0d931d8a32ccbc Author: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx> Date: Tue Apr 19 14:23:20 2022 +0200 Drivers: hv: vmbus: Fix handling of messages with transaction ID of zero [ Upstream commit 82cd4bacff88a11e36f143e2cb950174b09c86c3 ] vmbus_request_addr() returns 0 (zero) if the transaction ID passed to as argument is 0. This is unfortunate for two reasons: first, netvsc_send_completion() does not check for a NULL cmd_rqst (before dereferencing the corresponding NVSP message); second, 0 is a *valid* value of cmd_rqst in netvsc_send_tx_complete(), cf. the call of vmbus_sendpacket() in netvsc_send_pkt(). vmbus_request_addr() has included the code in question since its introduction with commit e8b7db38449ac ("Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening"); such code was motivated by the early use of vmbus_requestor by hv_storvsc. Since hv_storvsc moved to a tag-based mechanism to generate and retrieve transaction IDs with commit bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs"), vmbus_request_addr() can be modified to return VMBUS_RQST_ERROR if the ID is 0. This change solves the issues in hv_netvsc (and makes the handling of messages with transaction ID of 0 consistent with the semantics "the ID is not contained in the requestor/invalid ID"). vmbus_next_request_id(), vmbus_request_addr() should still reserve the ID of 0 for Hyper-V, because Hyper-V will "ignore" (not respond to) VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED packets/requests with transaction ID of 0 from the guest. Fixes: bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs") Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@xxxxxxxxx> Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220419122325.10078-2-parri.andrea@xxxxxxxxx Signed-off-by: Wei Liu <wei.liu@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index dc5c35210c16..20fc8d50a039 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -1245,7 +1245,9 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr) /* * Cannot return an ID of 0, which is reserved for an unsolicited - * message from Hyper-V. + * message from Hyper-V; Hyper-V does not acknowledge (respond to) + * VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED requests with ID of + * 0 sent by the guest. */ return current_id + 1; } @@ -1270,7 +1272,7 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id) /* Hyper-V can send an unsolicited message with ID of 0 */ if (!trans_id) - return trans_id; + return VMBUS_RQST_ERROR; spin_lock_irqsave(&rqstor->req_lock, flags);