[Virtio-fs] [PATCH 2/4] vhost-user: Interface for migration state transfer

[Hanna Czenczek]

On 09.05.23 08:31, Eugenio Perez Martin wrote:
> On Mon, May 8, 2023 at 9:12 PM Stefan Hajnoczi <stefanha at redhat.com> wrote:

[...]

>> VHOST_USER_GET_VRING_BASE itself isn't really enough because it stops a
>> specific virtqueue but not the whole device. Unfortunately stopping all
>> virtqueues is not the same as SUSPEND since spontaneous device activity
>> is possible independent of any virtqueue (e.g. virtio-scsi events and
>> maybe virtio-net link status).
>>
>> That's why I think SUSPEND is necessary for a solution that's generic
>> enough to cover all device types.
>>
> I agree.
>
> In particular virtiofsd is already resetting all the device at
> VHOST_USER_GET_VRING_BASE if I'm not wrong, so that's even more of a
> reason to implement suspend call.

Oh, no, just the vring in question.  Not the whole device.

In addition, we still need the GET_VRING_BASE call anyway, because, 
well, we want to restore the vring on the destination via SET_VRING_BASE.

Hanna