On Tue, Jul 11, 2023 at 05:52:22PM +0200, Hanna Czenczek wrote:
> Hi,
>
> As discussed on the previous version of the virtio-fs migration series
> (https://lists.nongnu.org/archive/html/qemu-devel/2023-04/msg01575.html),
> we currently don’t have a good way to have a vhost-user back-end fully
> cease all operations, including background operations. To work around
> this, we reset it, which is not an option for stateful devices like
> virtio-fs.
>
> Instead, we want the same SUSPEND/RESUME model that vhost-vdpa already
> has, so that we can suspend back-ends when we want them to stop doing
> anything (i.e. on VM stop), and resume them later (i.e. on VM resume).
> This series adds these vhost-user operations to the protocol and
> implements them in qemu. Furthermore, it has vhost-user and vhost-vdpa
> do roughly the same thing in their reset paths, as far as possible.
> That path will still remain as a fall-back if SUSPEND/RESUME is not
> implemented, and, given that qemu’s vhost-vdpa code currently does not
> make use of RESUME, it is actually always used for vhost-vdpa (to take
> the device out of a suspended state).
>
>
> Hanna Czenczek (6):
> vhost-user.rst: Add suspend/resume
> vhost-vdpa: Move vhost_vdpa_reset_status() up
> vhost: Do not reset suspended devices on stop
> vhost-user: Implement suspend/resume
> vhost-vdpa: Match vhost-user's status reset
> vhost-user: Have reset_status fall back to reset
>
> docs/interop/vhost-user.rst| 35 +++-
> include/hw/virtio/vhost-vdpa.h | 2 -
> include/hw/virtio/vhost.h | 8 +++
> hw/virtio/vhost-user.c | 101 -
> hw/virtio/vhost-vdpa.c | 41 ++---
> hw/virtio/vhost.c | 8 ++-
> 6 files changed, 169 insertions(+), 26 deletions(-)
Hi Hanna,
I posted comments but wanted to say great job! There was a long and
somewhat messy email discussion to figure out how to proceed and you
came up with a clean patch series that solves the issues.
Stefan
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