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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Halil Pasic <pasic@linux.ibm.com>,
        Michael Mueller <mimu@linux.ibm.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 135/151] virtio_ring: fix return code on DMA mapping fails
Date:   Wed, 27 Nov 2019 21:31:58 +0100
Message-Id: <20191127203046.747863171@linuxfoundation.org>
In-Reply-To: <20191127203000.773542911@linuxfoundation.org>
References: <20191127203000.773542911@linuxfoundation.org>
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From: Halil Pasic <pasic@linux.ibm.com>

[ 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.

Cc: stable@vger.kernel.org
Fixes: 780bc7903a32 ("virtio_ring: Support DMA APIs")
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 2f09294c59460..e459cd7302e27 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -427,7 +427,7 @@ unmap_release:
 		kfree(desc);
 
 	END_USE(vq);
-	return -EIO;
+	return -ENOMEM;
 }
 
 /**
-- 
2.20.1