vmbus_requestor has included code for handling unsolicited messages
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 from storvsc. Since
storvsc moved to a tag-based mechanism to generate/retrieve request IDs
with commit bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to
generate requestIDs"), the special handling of unsolicited messages in
vmbus_requestor is not useful and can be removed.
Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
---
drivers/hv/channel.c | 13 +------------
1 file changed, 1 insertion(+), 12 deletions(-)
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index dc5c35210c16a..a253eee3aeb1a 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -1243,11 +1243,7 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
spin_unlock_irqrestore(&rqstor->req_lock, flags);
- /*
- * Cannot return an ID of 0, which is reserved for an unsolicited
- * message from Hyper-V.
- */
- return current_id + 1;
+ return current_id;
}
EXPORT_SYMBOL_GPL(vmbus_next_request_id);
@@ -1268,15 +1264,8 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
if (!channel->rqstor_size)
return VMBUS_NO_RQSTOR;
- /* Hyper-V can send an unsolicited message with ID of 0 */
- if (!trans_id)
- return trans_id;
-
spin_lock_irqsave(&rqstor->req_lock, flags);
- /* Data corresponding to trans_id is stored at trans_id - 1 */
- trans_id--;
-
/* Invalid trans_id */
if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
spin_unlock_irqrestore(&rqstor->req_lock, flags);
--
2.25.1
From: Andrea Parri (Microsoft) <[email protected]> Sent: Monday, March 28, 2022 7:43 AM
>
> vmbus_requestor has included code for handling unsolicited messages
> 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 from storvsc. Since
> storvsc moved to a tag-based mechanism to generate/retrieve request IDs
> with commit bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to
> generate requestIDs"), the special handling of unsolicited messages in
> vmbus_requestor is not useful and can be removed.
>
> Signed-off-by: Andrea Parri (Microsoft) <[email protected]>
> ---
> drivers/hv/channel.c | 13 +------------
> 1 file changed, 1 insertion(+), 12 deletions(-)
>
> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
> index dc5c35210c16a..a253eee3aeb1a 100644
> --- a/drivers/hv/channel.c
> +++ b/drivers/hv/channel.c
> @@ -1243,11 +1243,7 @@ u64 vmbus_next_request_id(struct vmbus_channel
> *channel, u64 rqst_addr)
>
> spin_unlock_irqrestore(&rqstor->req_lock, flags);
>
> - /*
> - * Cannot return an ID of 0, which is reserved for an unsolicited
> - * message from Hyper-V.
> - */
> - return current_id + 1;
> + return current_id;
> }
> EXPORT_SYMBOL_GPL(vmbus_next_request_id);
>
> @@ -1268,15 +1264,8 @@ u64 vmbus_request_addr(struct vmbus_channel *channel,
> u64 trans_id)
> if (!channel->rqstor_size)
> return VMBUS_NO_RQSTOR;
>
> - /* Hyper-V can send an unsolicited message with ID of 0 */
> - if (!trans_id)
> - return trans_id;
> -
> spin_lock_irqsave(&rqstor->req_lock, flags);
>
> - /* Data corresponding to trans_id is stored at trans_id - 1 */
> - trans_id--;
> -
> /* Invalid trans_id */
> if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
> spin_unlock_irqrestore(&rqstor->req_lock, flags);
> --
> 2.25.1
Reviewed-by: Michael Kelley <[email protected]>
On Mon, Mar 28, 2022 at 04:42:41PM +0200, Andrea Parri (Microsoft) wrote:
> vmbus_requestor has included code for handling unsolicited messages
> 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 from storvsc. Since
> storvsc moved to a tag-based mechanism to generate/retrieve request IDs
> with commit bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to
> generate requestIDs"), the special handling of unsolicited messages in
> vmbus_requestor is not useful and can be removed.
As it turns out, this is not quite right. In particular...
> @@ -1243,11 +1243,7 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
>
> spin_unlock_irqrestore(&rqstor->req_lock, flags);
>
> - /*
> - * Cannot return an ID of 0, which is reserved for an unsolicited
> - * message from Hyper-V.
> - */
> - return current_id + 1;
> + return current_id;
Hyper-V treats requests with ID of 0 as "non-transactional" and it does
not respond to such requests.
> @@ -1268,15 +1264,8 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
> if (!channel->rqstor_size)
> return VMBUS_NO_RQSTOR;
>
> - /* Hyper-V can send an unsolicited message with ID of 0 */
> - if (!trans_id)
> - return trans_id;
This remains problematic: I will elaborate and propose some solution in
the next iteration (to be sent shortly).
Thanks,
Andrea
> -
> spin_lock_irqsave(&rqstor->req_lock, flags);
>
> - /* Data corresponding to trans_id is stored at trans_id - 1 */
> - trans_id--;
> -
> /* Invalid trans_id */
> if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
> spin_unlock_irqrestore(&rqstor->req_lock, flags);