Re: [virtio-dev] Re: [VIRTIO PCI PATCH v5 1/1] transport-pci: Add freeze_mode to virtio_pci_common_cfg

Chen, Jiqian
2023-09-27T09:20:33Z

On 2023/9/26 19:37, Parav Pandit wrote:
> Hi Jiqian,
>
>> From: Chen, Jiqian <Jiqian.Chen@amd.com>
>> Sent: Tuesday, September 26, 2023 4:30 PM
>
>> It is not to trigger resume behavior to device by setting unfreeze in my scenario.
>> You may misunderstand my intention.
>> In current kernel and qemu code, it will trigger reset device behavior by setting
>> device_status to 0 during resuming, and I found some operations of reset is not
>> reasonable during resuming, like virtio_gpu_reset, it will destroy render
>> resources and then caused the display gone after guest finishing reusming.
>
> When suspend is done, resume must not be done.
Why? During S3, we firstly suspend guest, and then resume guest, not do suspend and resume at the same time.

> I don’t see a need to mix these operations from guest specially when suspend is done.
>
> Did I miss your response for my suggestion few days ago in [1] for not mixing reset with suspend?
>
> When new feature bit of suspend is offered, guest will _not_ do reset, hence no need to mix reset with suspend.
I didn't express clearly before. I think I need to clarify two things.
1. I think you also misunderstood the intention of my patch. When I set freeze_S3, it is not to trigger a suspend to device, it just set a freeze status, and then device can do something according to the freeze status(not to freeze or reset device).
2. I didn't mix reset with suspend. Actually, in current kernel code, during S3, it does reset after suspend, and also does reset again before resume.

>
> [1] https://lists.oasis-open.org/archives/virtio-comment/202309/msg00260.html

--
Best regards,
Jiqian Chen.