Will be in the next pull request.
On Tue, Nov 19, 2019 at 12:10:22PM +0100, Halil Pasic wrote:
> ping
>
> On Thu, 14 Nov 2019 13:46:46 +0100
> Halil Pasic <pasic@xxxxxxxxxxxxx> wrote:
>
> > 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 <pasic@xxxxxxxxxxxxx>
> > Tested-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
> > ---
> >
> > Notes
> > =====
> >
> > * When out of descriptors (which might regarded as a similar out of
> > resources condition) virtio uses -ENOSPC, this however seems wrong,
> > as ENOSPC is defined as -ENOSPC. Thus I choose -ENOMEM over -ENOSPC.
> >
> > * In virtio_queue_rq() in virtio_blk.c both -ENOMEM and -ENOSPC are
> > handled as BLK_STS_DEV_RESOURCE. Returning BLK_STS_RESOURCE however
> > seems more appropriate for dma mapping failed as we are talking about
> > a global, and not a device local resource. Both seem to do the trick.
> >
> > * Mimu tested the patch with virtio-blk and virtio-net (thanks!). We
> > should look into how other virtio devices behave when DMA mapping fails.
> > ---
> > drivers/virtio/virtio_ring.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> > index a8041e451e9e..867c7ebd3f10 100644
> > --- a/drivers/virtio/virtio_ring.c
> > +++ b/drivers/virtio/virtio_ring.c
> > @@ -583,7 +583,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
> > kfree(desc);
> >
> > END_USE(vq);
> > - return -EIO;
> > + return -ENOMEM;
> > }
> >
> > static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
> > @@ -1085,7 +1085,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
> > kfree(desc);
> >
> > END_USE(vq);
> > - return -EIO;
> > + return -ENOMEM;
> > }
> >
> > static inline int virtqueue_add_packed(struct virtqueue *_vq,
