Re: [PATCH 1/2] vdpa: support per virtqueue max queue size

[Stefan Hajnoczi]

On Mon, Jul 05, 2021 at 03:19:09PM +0800, Jason Wang wrote:
> Virtio spec allows the device to specify the per virtqueue max queue
> size. vDPA needs to adapt to this flexibility. E.g Qemu advertise a
> small control virtqueue for virtio-net.
> 
> So this patch adds a index parameter to get_vq_num_max bus operations
> for the device to report its per virtqueue max queue size.
> 
> Both VHOST_VDPA_GET_VRING_NUM and VDPA_ATTR_DEV_MAX_VQ_SIZE assume a
> global maximum size. So we iterate all the virtqueues to return the
> minimal size in this case. Actually, the VHOST_VDPA_GET_VRING_NUM is
> not a must for the userspace. Userspace may choose to check the
> VHOST_SET_VRING_NUM for proving or validating the maximum virtqueue
> size. Anyway, we can invent a per vq version of
> VHOST_VDPA_GET_VRING_NUM in the future if it's necessary.
> 
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
>  drivers/vdpa/ifcvf/ifcvf_main.c   |  2 +-
>  drivers/vdpa/mlx5/net/mlx5_vnet.c |  2 +-
>  drivers/vdpa/vdpa.c               | 22 +++++++++++++++++++++-
>  drivers/vdpa/vdpa_sim/vdpa_sim.c  |  2 +-
>  drivers/vdpa/virtio_pci/vp_vdpa.c |  2 +-
>  drivers/vhost/vdpa.c              |  9 ++++++---
>  drivers/virtio/virtio_vdpa.c      |  2 +-
>  include/linux/vdpa.h              |  5 ++++-
>  8 files changed, 36 insertions(+), 10 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>

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