Re: [Qemu-devel] [RFC 3/3] vhost-user: add VFIO based accelerators support

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 22 Dec 2017 14:41:51 +0800
Tiwei Bie <tiwei.bie@intel.com> wrote:

> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> ---
>  docs/interop/vhost-user.txt    |  57 ++++++
>  hw/vfio/common.c               |   2 +-
>  hw/virtio/vhost-user.c         | 381 ++++++++++++++++++++++++++++++++++++++++-
>  hw/virtio/vhost.c              |   3 +-
>  hw/virtio/virtio-pci.c         |   8 -
>  hw/virtio/virtio-pci.h         |   8 +
>  include/hw/vfio/vfio.h         |   2 +
>  include/hw/virtio/vhost-user.h |  26 +++
>  8 files changed, 476 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 7b2924c0ef..53d8700581 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -49,7 +49,7 @@ struct vfio_as_head vfio_address_spaces =
>   * initialized, this file descriptor is only released on QEMU exit and
>   * we'll re-use it should another vfio device be attached before then.
>   */
> -static int vfio_kvm_device_fd = -1;
> +int vfio_kvm_device_fd = -1;
>  #endif

It seems troublesome for vhost to maintain it's own list of groups and
register them with the vfio-kvm device.  These should likely be made
into services provided by vfio/common.c such that we can have a single
group list and interfaces for adding and deleting them.  Thanks,

Alex