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Subject[PATCH 4.19 291/306] virtio_ring: fix return code on DMA mapping fails
From: Halil Pasic <>

[ Upstream commit f7728002c1c7bfa787b276a31c3ef458739b8e7c ]

Commit 780bc7903a32 ("virtio_ring: Support DMA APIs") makes
virtqueue_add() return -EIO when we fail to map our I/O buffers. This is
a very realistic scenario for guests with encrypted memory, as swiotlb
may run out of space, depending on it's size and the I/O load.

The virtio-blk driver interprets -EIO form virtqueue_add() as an IO
error, despite the fact that swiotlb full is in absence of bugs a
recoverable condition.

Let us change the return code to -ENOMEM, and make the block layer
recover form these failures when virtio-blk encounters the condition
described above.

Fixes: 780bc7903a32 ("virtio_ring: Support DMA APIs")
Signed-off-by: Halil Pasic <>
Tested-by: Michael Mueller <>
Signed-off-by: Michael S. Tsirkin <>
Signed-off-by: Sasha Levin <>
drivers/virtio/virtio_ring.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 9529e28e18222..6228b48d1e127 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -431,7 +431,7 @@ unmap_release:

- return -EIO;
+ return -ENOMEM;


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