Re: [PATCH v3 0/3] virtio DMA API core stuff

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Oct 27, 2015 at 11:38:57PM -0700, Andy Lutomirski wrote:
> This switches virtio to use the DMA API unconditionally.  I'm sure
> it breaks things, but it seems to work on x86 using virtio-pci, with
> and without Xen, and using both the modern 1.0 variant and the
> legacy variant.

I'm very glad to see work on this making progress.

I suspect we'll have to find a way to make this optional though, and
keep doing the non-DMA API thing with old devices.  And I've been
debating with myself whether a pci specific thing or a feature bit is
preferable.

Thoughts?

> Changes from v2:
>  - Fix really embarrassing bug.  This version actually works.
> 
> Changes from v1:
>  - Fix an endian conversion error causing a BUG to hit.
>  - Fix a DMA ordering issue (swiotlb=force works now).
>  - Minor cleanups.
> 
> Andy Lutomirski (3):
>   virtio_net: Stop doing DMA from the stack
>   virtio_ring: Support DMA APIs
>   virtio_pci: Use the DMA API
> 
>  drivers/net/virtio_net.c           |  53 +++++++----
>  drivers/virtio/Kconfig             |   2 +-
>  drivers/virtio/virtio_pci_common.h |   3 +-
>  drivers/virtio/virtio_pci_legacy.c |  19 +++-
>  drivers/virtio/virtio_pci_modern.c |  34 +++++--
>  drivers/virtio/virtio_ring.c       | 187 ++++++++++++++++++++++++++++++-------
>  tools/virtio/linux/dma-mapping.h   |  17 ++++
>  7 files changed, 246 insertions(+), 69 deletions(-)
>  create mode 100644 tools/virtio/linux/dma-mapping.h
> 
> -- 
> 2.4.3