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
> --
> 2.27.0
>
>
>