Re: [PATCH v2] vhost-vdpa: Set discarding of RAM broken when initializing the backend

[Stefano Garzarella <sgarzare@redhat.com>]

On Wed, Oct 27, 2021 at 03:03:24PM +0200, David Hildenbrand wrote:
>Similar to VFIO, vDPA will go ahead an map+pin all guest memory. Memory
>that used to be discarded will get re-populated and if we
>discard+re-access memory after mapping+pinning, the pages mapped into the
>vDPA IOMMU will go out of sync with the actual pages mapped into the user
>space page tables.
>
>Set discarding of RAM broken such that:
>- virtio-mem and vhost-vdpa run mutually exclusive
>- virtio-balloon is inhibited and no memory discards will get issued
>
>In the future, we might be able to support coordinated discarding of RAM
>as used by virtio-mem and already supported by vfio via the
>RamDiscardManager.
>
>Acked-by: Jason Wang <jasowang@redhat.com>
>Cc: Jason Wang <jasowang@redhat.com>
>Cc: Michael S. Tsirkin <mst@redhat.com>
>Cc: Cindy Lu <lulu@redhat.com>
>Signed-off-by: David Hildenbrand <david@redhat.com>
>---
>
>Unfortuantely, v1 never got picked up no matter how "hard" I tried to
>ping :)
>
>v1 -> v2:
>- Add ack from Jason
>- Extend patch description now that RamDiscardManager is upstream.
>
>---
> hw/virtio/vhost-vdpa.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>