Re: [PATCH V2 2/2] virtio: support IOMMU platform

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

On Wed, Sep 28, 2016 at 04:25:12PM +0800, Jason Wang wrote:
> Negotiate VIRTIO_F_IOMMU_PLATFORM to have IOMMU support.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
> Changes from v1:
> - remove unnecessary NEED_MAPPING flag

One thing we probably should do is enable this flag
with VFIO but not with UIO or VFIO-noiommu.

> ---
>  drivers/net/virtio/virtio_ethdev.h | 3 ++-
>  drivers/net/virtio/virtio_pci.h    | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.h b/drivers/net/virtio/virtio_ethdev.h
> index 2ecec6e..04a06e2 100644
> --- a/drivers/net/virtio/virtio_ethdev.h
> +++ b/drivers/net/virtio/virtio_ethdev.h
> @@ -63,7 +63,8 @@
>  	 1u << VIRTIO_NET_F_CTRL_RX	  |	\
>  	 1u << VIRTIO_NET_F_CTRL_VLAN	  |	\
>  	 1u << VIRTIO_NET_F_MRG_RXBUF	  |	\
> -	 1ULL << VIRTIO_F_VERSION_1)
> +	 1ULL << VIRTIO_F_VERSION_1       |	\
> +	 1ULL << VIRTIO_F_IOMMU_PLATFORM )

Space before ) looks kind of ugly.

>  
>  /*
>   * CQ function prototype
> diff --git a/drivers/net/virtio/virtio_pci.h b/drivers/net/virtio/virtio_pci.h
> index 3430a39..0aa0015 100644
> --- a/drivers/net/virtio/virtio_pci.h
> +++ b/drivers/net/virtio/virtio_pci.h
> @@ -138,6 +138,7 @@ struct virtnet_ctl;
>  #define VIRTIO_RING_F_INDIRECT_DESC	28
>  
>  #define VIRTIO_F_VERSION_1		32
> +#define VIRTIO_F_IOMMU_PLATFORM	33
>  
>  /*
>   * Some VirtIO feature bits (currently bits 28 through 31) are
> @@ -145,7 +146,7 @@ struct virtnet_ctl;
>   * rest are per-device feature bits.
>   */
>  #define VIRTIO_TRANSPORT_F_START 28
> -#define VIRTIO_TRANSPORT_F_END   32
> +#define VIRTIO_TRANSPORT_F_END   34
>  

This seems unused. Drop it?

>  /* The Guest publishes the used index for which it expects an interrupt
>   * at the end of the avail ring. Host should ignore the avail->flags field. */
> -- 
> 2.7.4