@@ -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);
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@gmail.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> --- The above hv_netvsc issues precede bf5fd8cae3c8f; however, these changes should not be backported to earlier commits since such a back-port would 'break' hv_storvsc. drivers/hv/channel.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)