On Tue, Aug 15, 2023 at 03:28:59AM +0800, Zhu Lingshan wrote:
> This seires introduces
> 1)a new SUSPEND bit in the device status
> Which is used to suspend the device, so that the device states
> and virtqueue states are stablized.
>
> 2)virtqueue state and accessors, to get and set last_avail_idx
> and last_used_idx of virtqueues.
>
> The main usecase of these new facilities is Live Migration.
>
> Furture work: dirty page tracking and in-flight descriptors.
>
> This is RFC, this series carries on Jason and Eugenio's pervious work.
>
> Any comments are welcome.
In order to support stateful devices like virtiofs, virtio-gpu, or
virtio-crypto it would be necessary to add device state save/load
functionality too.
Even virtio-net needs device state save/load functionality if the VMM is
not intercepting the stateful controlq.
In-flight descriptors can be included in the device state.
In fact, the only reason why I think VIRTIO_F_QUEUE_STATE makes sense is
for easy integration into existing vhost software stacks. Otherwise we
should just define a device state save/load interface along with
standard device state serialization for devices where migration
interoperability is possible. VIRTIO_F_QUEUE_STATE is a small subset of
device state save/load.
I think the convenience of integrating into existing vhost software
stacks is worth the duplication, but I wanted to mention that this
interface will not be enough to live migrate all device types and we'll
need something more in the future.
Stefan
>
> Zhu Lingshan (5):
> virtio: introduce SUSPEND bit in device status
> virtio: introduce vq state as basic facility
> virtio: The actions by the device upon SUSPEND
> virtqueue: constraints for virtqueue state
> virtio-pci: implement VIRTIO_F_QUEUE_STATE
>
> content.tex | 120 ++++++++++++++++++++++++++++++++++++++++++++++
> transport-pci.tex | 15 ++++++
> 2 files changed, 135 insertions(+)
>
> --
> 2.35.3
>
>
> This publicly archived list offers a means to provide input to the
> OASIS Virtual I/O Device (VIRTIO) TC.
>
> In order to verify user consent to the Feedback License terms and
> to minimize spam in the list archive, subscription is required
> before posting.
>
> Subscribe:
> Unsubscribe:
> List help:
> List archive: https://lists.oasis-open.org/archives/virtio-comment/
> Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf
> List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists
> Committee: https://www.oasis-open.org/committees/virtio/
> Join OASIS: https://www.oasis-open.org/join/
>
