Message-ID: <20230911100430.1408168-1-Jiqian.Chen@amd.com>
Date:   Mon, 11 Sep 2023 18:04:29 +0800
From:   Jiqian Chen <Jiqian.Chen@....com>
To:     Gerd Hoffmann <kraxel@...hat.com>,
        Marc-André Lureau <marcandre.lureau@...il.com>,
        Robert Beckett <bob.beckett@...labora.com>,
        <virtio-comment@...ts.oasis-open.org>,
        <virtio-dev@...ts.oasis-open.org>
CC:     <qemu-devel@...gnu.org>, <linux-kernel@...r.kernel.org>,
        "Stefano Stabellini" <sstabellini@...nel.org>,
        Roger Pau Monné <roger.pau@...rix.com>,
        Alex Deucher <Alexander.Deucher@....com>,
        "Christian Koenig" <Christian.Koenig@....com>,
        Stewart Hildebrand <Stewart.Hildebrand@....com>,
        Xenia Ragiadakou <burzalodowa@...il.com>,
        Honglei Huang <Honglei1.Huang@....com>,
        Julia Zhang <Julia.Zhang@....com>,
        Huang Rui <Ray.Huang@....com>,
        Jiqian Chen <Jiqian.Chen@....com>
Subject: [RESEND VIRTIO GPU PATCH v3 0/1] Add new feature flag VIRTIO_GPU_F_FREEZE_S3

Hi all,
I hope you’ll forgive me if this disturb you. Since it has been almost two
months since the latest patch was sent out, I didn't receive any reply, so I
rebase the latest master branch and sent it again. I am looking forward to
getting your response.

Best regards,
Jiqian Chen

v3:
Hi all,
Thanks for Gerd Hoffmann's advice. V3 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.
* Explain in more detail

And latest version on QEMU and Linux kernel side:
	QEMU: https://lore.kernel.org/qemu-devel/20230720120816.8751-1-Jiqian.Chen@amd.com
	Kernel: https://lore.kernel.org/lkml/20230720115805.8206-1-Jiqian.Chen@amd.com/T/#t


v2:
Hi all,
Thanks to Gerd Hoffmann for his suggestions. V2 makes below changes:
* Elaborate on the types of resources.
* Add some descriptions for S3 and S4.

Link:
https://lists.oasis-open.org/archives/virtio-comment/202307/msg00160.html
V2 of Qemu patch:
https://lore.kernel.org/qemu-devel/20230630070016.841459-1-Jiqian.Chen@amd.com/T/#t
V2 of Kernel patch:
https://lore.kernel.org/lkml/20230630073448.842767-1-Jiqian.Chen@amd.com/T/#t


v1:
Hi all,
I am working to implement virtgpu S3 function on Xen.

Currently on Xen, if we start a guest through Qemu with enabling virtgpu, and then suspend
and s3resume guest. We can find that the guest kernel comes back, but the display doesn't.
It just shown a black screen.

That is because when guest was during suspending, it called into Qemu and Qemu destroyed
all resources and reset renderer. This made the display gone after guest resumed.

So, I add a mechanism that when guest is suspending, it will notify Qemu, and then Qemu will
not destroy resources. That can help guest's display come back.

As discussed and suggested by Robert Beckett and Gerd Hoffmann on v1 qemu's mailing list.
Due to that mechanism needs cooperation between guest and host. What's more, as virtio drivers
by design paravirt drivers, it is reasonable for guest to accept some cooperation with host to
manage suspend/resume. So I request to add a new feature flag, so that guest and host can
negotiate whenever freezing is supported or not.

Link:
https://lists.oasis-open.org/archives/virtio-comment/202306/msg00595.html
V1 of Qemu patch:
https://lore.kernel.org/qemu-devel/20230608025655.1674357-2-Jiqian.Chen@amd.com/
V1 of Kernel patch:
https://lore.kernel.org/lkml/20230608063857.1677973-1-Jiqian.Chen@amd.com/

Jiqian Chen (1):
  virtio-gpu: Add new feature flag VIRTIO_GPU_F_FREEZE_S3

 device-types/gpu/description.tex | 42 ++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

-- 
2.34.1

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