scsi: storvsc: Fix swiotlb bounce buffer leak in confidential VM

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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: 743b237c3a ("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@microsoft.com
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>

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Michael Kelley 2022-12-04 11:52:44 -08:00 • committed by Martin K. Petersen

parent a3be19b91e

commit 67ff3d0a49

1 changed files with 3 additions and 0 deletions

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drivers/scsi/storvsc_drv.c

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