Re: [QEMU PATCH v4 0/1] S3 support

["Chen, Jiqian" <Jiqian.Chen@xxxxxxx>]

Hi all,
Please forgive me for asking. Do you have any other comments on my latest 
version patches about virtio-gpu S3 on Xen? Looking forward to your reply.


On 2023/7/20 20:08, Jiqian Chen wrote:
> v4:
> 
> Hi all,
> Thanks for Gerd Hoffmann's advice. V4 makes below changes:
> * Use enum for freeze mode, so this can be extended with more
>   modes in the future.
> * Rename functions and paratemers with "_S3" postfix.
> And no functional changes.
> 
> latest version on kernel side:
> https://lore.kernel.org/lkml/20230720115805.8206-1-Jiqian.Chen@xxxxxxx/T/#t
> 
> Best regards,
> Jiqian Chen.
> 
> 
> v3:
> link,
> https://lore.kernel.org/qemu-devel/20230719074726.1613088-1-Jiqian.Chen@xxxxxxx/T/#t
> 
> Hi all,
> Thanks for Michael S. Tsirkin's advice. V3 makes below changes:
> * Remove changes in file include/standard-headers/linux/virtio_gpu.h
>   I am not supposed to edit this file and it will be imported after
>   the patches of linux kernel was merged.
> 
> 
> v2:
> link,
> https://lore.kernel.org/qemu-devel/20230630070016.841459-1-Jiqian.Chen@xxxxxxx/T/#t
> 
> Hi all,
> Thanks to Marc-André Lureau, Robert Beckett and Gerd Hoffmann for
> their advice and guidance. V2 makes below changes:
> 
> * Change VIRTIO_CPU_CMD_STATUS_FREEZING to 0x0400 (<0x1000)
> * Add virtio_gpu_device_unrealize to destroy resources to solve
>   potential memory leak problem. This also needs hot-plug support.
> * Add a new feature flag VIRTIO_GPU_F_FREEZING, so that guest and
>   host can negotiate whenever freezing is supported or not.
> 
> v1:
> link,
> https://lore.kernel.org/qemu-devel/20230608025655.1674357-1-Jiqian.Chen@xxxxxxx/
> 
> Hi all,
> I am working to implement virtgpu S3 function on Xen.
> 
> Currently on Xen, if we start a guest who enables virtgpu, and then
> run "echo mem > /sys/power/state" to suspend guest. And run
> "sudo xl trigger <guest id> s3resume" to resume guest. We can find that
> the guest kernel comes back, but the display doesn't. It just shown a
> black screen.
> 
> Through reading codes, I founded that when guest was during suspending,
> it called into Qemu to call virtio_gpu_gl_reset. In virtio_gpu_gl_reset,
> it destroyed all resources and reset renderer. This made the display
> gone after guest resumed.
> 
> I think we should keep resources or prevent they being destroyed when
> guest is suspending. So, I add a new status named freezing to virtgpu,
> and add a new ctrl message VIRTIO_GPU_CMD_STATUS_FREEZING to get
> notification from guest. If freezing is set to true, and then Qemu will
> realize that guest is suspending, it will not destroy resources and will
> not reset renderer. If freezing is set to false, Qemu will do its origin
> actions, and has no other impaction.
> 
> And now, display can come back and applications can continue their
> status after guest resumes.
> 
> Jiqian Chen (1):
>   virtgpu: do not destroy resources when guest suspend
> 
>  hw/display/virtio-gpu-base.c   |  3 ++
>  hw/display/virtio-gpu-gl.c     | 10 ++++++-
>  hw/display/virtio-gpu-virgl.c  |  7 +++++
>  hw/display/virtio-gpu.c        | 55 ++++++++++++++++++++++++++++++++--
>  hw/virtio/virtio.c             |  3 ++
>  include/hw/virtio/virtio-gpu.h |  6 ++++
>  6 files changed, 81 insertions(+), 3 deletions(-)
> 

-- 
Best regards,
Jiqian Chen.