From: Michael Kelley mikelley@microsoft.com
[ Upstream commit 67ff3d0a49f3d445c3922e30a54e03c161da561e ]
storvsc_queuecommand() maps the scatter/gather list using scsi_dma_map(), which in a confidential VM allocates swiotlb bounce buffers. If the I/O submission fails in storvsc_do_io(), the I/O is typically retried by higher level code, but the bounce buffer memory is never freed. The mostly like cause of I/O submission failure is a full VMBus channel ring buffer, which is not uncommon under high I/O loads. Eventually enough bounce buffer memory leaks that the confidential VM can't do any I/O. The same problem can arise in a non-confidential VM with kernel boot parameter swiotlb=force.
Fix this by doing scsi_dma_unmap() in the case of an I/O submission error, which frees the bounce buffer memory.
Fixes: 743b237c3a7b ("scsi: storvsc: Add Isolation VM support for storvsc driver") Signed-off-by: Michael Kelley mikelley@microsoft.com Link: https://lore.kernel.org/r/1670183564-76254-1-git-send-email-mikelley@microso... Tested-by: Dexuan Cui decui@microsoft.com Reviewed-by: Dexuan Cui decui@microsoft.com Reviewed-by: Tianyu Lan Tianyu.Lan@microsoft.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/storvsc_drv.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 3c5b7e4227b2..55d6fb452680 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -1823,6 +1823,9 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd) ret = storvsc_do_io(dev, cmd_request, get_cpu()); put_cpu();
+ if (ret) + scsi_dma_unmap(scmnd); + if (ret == -EAGAIN) { /* no more space */ ret = SCSI_MLQUEUE_DEVICE_BUSY;