Re: [PATCH v3 0/5] virtio: Clean up scatterlists and use the DMA API

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 29/08/14 01:51, Andy Lutomirski wrote:
> This fixes virtio on Xen guests as well as on any other platform
> that uses virtio_pci on which physical addresses don't match bus
> addresses.
> 
> This can be tested with:
> 
>     virtme-run --xen xen --kimg arch/x86/boot/bzImage --console
> 
> using virtme from here:
> 
>     https://git.kernel.org/cgit/utils/kernel/virtme/virtme.git
> 
> Without these patches, the guest hangs forever.  With these patches,
> everything works.
> 
> This should be safe on all platforms that I'm aware of.  That
> doesn't mean that there isn't anything that I missed.
> 
> Patches 4 and 5 are optional cleanups.  I strongly encourage the
> virtio maintainers to apply patch 4, since it should be a very minor
> speedup as well as a cleanup, and patch 4 is critical fix if patch 5
> is applied.
> 
> Patch 5 is last for ease of reversion in case it causes problems.
> It is not necessary for DMA mappings to work, and it does not fix
> any bugs that I know of.  It's just a cleanup.
> 
> Thanks to everyone for putting up with the development of this
> series.  Hopefully it'll be the end of DMA issues in virtio. :)
> 
> Changes from v2:
>  - Reordered patches.
>  - Fixed a virtio_net OOPS.
> 
> Changes from v1:
>  - Using the DMA API is optional now.  It would be nice to improve the
>    DMA API to the point that it could be used unconditionally, but s390
>    proves that we're not there yet.
>  - Includes patch 4, which fixes DMA debugging warnings from virtio_net.
> 
> Andy Lutomirski (5):
>   virtio_ring: Support DMA APIs if requested
>   virtio_pci: Use the DMA API for virtqueues
>   virtio_net: Stop doing DMA from the stack
>   virtio_net: Don't set the end flag on reusable sg entries
>   virtio_ring: Remove sg_next indirection
> 
>  drivers/lguest/lguest_device.c         |   3 +-
>  drivers/misc/mic/card/mic_virtio.c     |   2 +-
>  drivers/net/virtio_net.c               |  59 ++++++---
>  drivers/remoteproc/remoteproc_virtio.c |   4 +-
>  drivers/s390/kvm/kvm_virtio.c          |   2 +-
>  drivers/s390/kvm/virtio_ccw.c          |   4 +-
>  drivers/virtio/virtio_mmio.c           |   5 +-
>  drivers/virtio/virtio_pci.c            |  35 ++++--
>  drivers/virtio/virtio_ring.c           | 219 ++++++++++++++++++++++++++-------
>  include/linux/virtio_ring.h            |   1 +
>  tools/virtio/linux/virtio.h            |   1 +
>  tools/virtio/virtio_test.c             |   2 +-
>  tools/virtio/vringh_test.c             |   3 +-
>  13 files changed, 256 insertions(+), 84 deletions(-)
> 

This series seems to work fine on s390-ccw. Thanks for the quick updates.

Christian