Re: [PATCH v3 0/5] Move ASID test to vhost-vdpa net initialization

[Lei Yang]

QE tested this series with sanity testing on the vdpa_sim device,
everything are works fine and there is no any new regression problems.

Tested-by: Lei Yang <leiyang@redhat.com>



On Tue, May 9, 2023 at 11:44 PM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> QEMU v8.0 is able to switch dynamically between vhost-vdpa passthrough
> and SVQ mode as long as the net device does not have CVQ.  The net device
> state followed (and migrated) by CVQ requires special care.
>
> A pre-requisite to add CVQ to that framework is to determine if devices with
> CVQ are migratable or not at initialization time.  The solution to it is to
> always shadow only CVQ, and vq groups and ASID are used for that.
>
> However, current qemu version only checks ASID at device start (as "driver set
> DRIVER_OK status bit"), not at device initialization.  A check at
> initialization time is required.  Otherwise, the guest would be able to set
> and remove migration blockers at will [1].
>
> This series is a requisite for migration of vhost-vdpa net devices with CVQ.
> However it already makes sense by its own, as it reduces the number of ioctls
> at migration time, decreasing the error paths there.
>
> [1] 
> https://lore.kernel.org/qemu-devel/2616f0cd-f9e8-d183-ea78-db1be4825d9c@redhat.com/
> ---
> v3:
> * Only record cvq_isolated, true if the device have cvq isolated in both !MQ
> * and MQ configurations.
> * Drop the cache of cvq group, it can be done on top
>
> v2:
> * Take out the reset of the device from vhost_vdpa_cvq_is_isolated
>   (reported by Lei Yang).
> * Expand patch messages by Stefano G. questions.
>
> Eugenio Pérez (5):
>   vdpa: Remove status in reset tracing
>   vdpa: add vhost_vdpa_reset_status_fd
>   vdpa: add vhost_vdpa_set_dev_features_fd
>   vdpa: return errno in vhost_vdpa_get_vring_group error
>   vdpa: move CVQ isolation check to net_init_vhost_vdpa
>
>  include/hw/virtio/vhost-vdpa.h |   2 +
>  hw/virtio/vhost-vdpa.c         |  78 ++++++++++-----
>  net/vhost-vdpa.c               | 171 ++++++++++++++++++++++++++-------
>  hw/virtio/trace-events         |   2 +-
>  4 files changed, 192 insertions(+), 61 deletions(-)
>
> --
> 2.31.1
>
>