Re: [RFC v3 15/29] vhost: Add enable_custom_iommu to VhostOps

[Jason Wang]

在 2021/5/20 上午12:28, Eugenio Pérez 写道:
> This operation enable the backend-specific IOTLB entries.
>
> If a backend support this, it start managing its own entries, and vhost
> can disable it through this operation and recover control.
>
> Every enable/disable operation must also clear all IOTLB device entries.
>
> At the moment, the only backend that does so is vhost-vdpa. To fully
> support these, vdpa needs also to expose a way for vhost subsystem to
> map and unmap entries. This will be done in future commits.
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>


I think there's probably no need to introduce this helper.

Instead, we can introduce ops like shadow_vq_start()/stop(). Then the 
details like this could be hided there.

(And hide the backend deatils (avoid calling vhost_vdpa_dma_map()) 
directly from the vhost.c)

Thanks


> ---
>   include/hw/virtio/vhost-backend.h | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/include/hw/virtio/vhost-backend.h 
> b/include/hw/virtio/vhost-backend.h
> index bcb112c166..f8eed2ace5 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -128,6 +128,9 @@ typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
>   
>   typedef int (*vhost_vring_pause_op)(struct vhost_dev *dev);
>   
> +typedef int (*vhost_enable_custom_iommu_op)(struct vhost_dev *dev,
> +                                            bool enable);
> +
>   typedef int (*vhost_get_iova_range)(struct vhost_dev *dev,
>                                       hwaddr *first, hwaddr *last);
>   
> @@ -177,6 +180,7 @@ typedef struct VhostOps {
>       vhost_get_device_id_op vhost_get_device_id;
>       vhost_vring_pause_op vhost_vring_pause;
>       vhost_force_iommu_op vhost_force_iommu;
> +    vhost_enable_custom_iommu_op vhost_enable_custom_iommu;
>       vhost_get_iova_range vhost_get_iova_range;
>   } VhostOps;
>