Re: [RFC PATCH 0/9] Net Control VQ support in vDPA SVQ

[Eugenio Perez Martin]

On Mon, Feb 14, 2022 at 8:38 PM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> Control virtqueue is used by networking device for accepting various
> commands from the driver. It's a must to support multiqueue and other
> configurations.
>
> Shadow VirtQueue (SVQ) [1] already makes possible migration of virtqueue
> states, effectively intercepting them so qemu can track what regions of memory
> are dirty because device action and needs migration. However, this does not
> solve networking device state seen by the driver because CVQ messages, like
> changes on MAC addresses from the driver.
>
> To solve that, this series uses SVQ infraestructure proposed at SVQ [1] to
> intercept networking control messages used by the device. This way, qemu is
> able to update VirtIONet device model and to migrate it. This series needs to
> be applied on top of [1].
>
> Ideally, only the control VQ would be shadowed for all the run of qemu and the
> rest of virtqueues would be passthrough unless it's migration time. However,
> this requires the vDPA device to support address translations from more than
> one address space, something that is not possible at the moment with the
> current vhost-vDPA API. The API change has been proposed at [2], but use of it
> is left for future series.
>
> Sending this as a RFC so some details like error control is still not 100%
> tested. Comments are welcomed on every aspect of the patch.
>
> [1] 
> https://lore.kernel.org/qemu-devel/20220121202733.404989-1-eperezma@redhat.com/
> [2] https://lkml.org/lkml/2020/9/23/1243
>
> Eugenio Pérez (9):
>   virtio-net: Expose ctrl virtqueue logic
>   vdpa: Extract get geatures part from vhost_vdpa_get_max_queue_pairs
>   virtio: Make virtqueue_alloc_element non-static
>   vhost: Add SVQElement
>   vhost: Add custom used buffer callback
>   vdpa: Add map/unmap operation callback to SVQ
>   vhost: Add vhost_svq_inject
>   vhost: Add vhost_svq_start_op
>   vdpa: control virtqueue support on shadow virtqueue
>
>  hw/virtio/vhost-shadow-virtqueue.h |  25 +++-
>  include/hw/virtio/vhost-vdpa.h     |   2 +
>  include/hw/virtio/virtio-net.h     |   3 +
>  include/hw/virtio/virtio.h         |   1 +
>  hw/net/virtio-net.c                |  83 ++++++-----
>  hw/virtio/vhost-shadow-virtqueue.c | 217 +++++++++++++++++++++++------
>  hw/virtio/vhost-vdpa.c             |  22 ++-
>  hw/virtio/virtio.c                 |   2 +-
>  net/vhost-vdpa.c                   | 140 +++++++++++++++++--
>  9 files changed, 405 insertions(+), 90 deletions(-)
>

This series is available to test at [1].

Thanks!

[1] 
https://github.com/eugpermar/qemu/releases/tag/vdpa_sw_live_migration.d%2Fcvq-v1

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