From: Gurchetan Singh <gurchetansingh@chromium.org>
To: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Cc: "David Stevens" <stevensd@chromium.org>,
"Stefan Hajnoczi" <stefanha@gmail.com>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Keiichi Watanabe" <keiichiw@chromium.org>,
geoff@hostfission.com, virtio-dev@lists.oasis-open.org,
"Alex Lau" <alexlau@chromium.org>,
"Alexandre Courbot" <acourbot@chromium.org>,
qemu-devel@nongnu.org, "Tomasz Figa" <tfiga@chromium.org>,
"Hans Verkuil" <hverkuil@xs4all.nl>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Stéphane Marchesin" <marcheu@chromium.org>,
"Dylan Reid" <dgreid@chromium.org>,
"Dmitry Morozov" <dmitry.morozov@opensynergy.com>,
"Pawel Osciak" <posciak@chromium.org>,
"Linux Media Mailing List" <linux-media@vger.kernel.org>
Subject: Re: [virtio-dev] Re: guest / host buffer sharing ...
Date: Mon, 11 Nov 2019 16:54:14 -0800 [thread overview]
Message-ID: <CAAfnVBkMWurTpseQFjcna5kk3__40n6M68=RTHLbQsu__2AFxg@mail.gmail.com> (raw)
In-Reply-To: <c8a6b6f35664ce036c2a48ec41eab97b0f40704d.camel@linux.intel.com>
On Tue, Nov 5, 2019 at 2:55 AM Gerd Hoffmann <kraxel@redhat.com> wrote:
> Each buffer also has some properties to carry metadata, some fixed (id, size, application), but
> also allow free form (name = value, framebuffers would have
> width/height/stride/format for example).
Sounds a lot like the recently added DMA_BUF_SET_NAME ioctls:
https://patchwork.freedesktop.org/patch/310349/
For virtio-wayland + virtio-vdec, the problem is sharing -- not allocation.
As the buffer reaches a kernel boundary, it's properties devolve into
[fd, size]. Userspace can typically handle sharing metadata. The
issue is the guest dma-buf fd doesn't mean anything on the host.
One scenario could be:
1) Guest userspace (say, gralloc) allocates using virtio-gpu. When
allocating, we call uuidgen() and then pass that via RESOURCE_CREATE
hypercall to the host.
2) When exporting the dma-buf, we call DMA_BUF_SET_NAME (the buffer
name will be "virtgpu-buffer-${UUID}").
3) When importing, virtio-{vdec, video} reads the dma-buf name in
userspace, and calls fd to handle. The name is sent to the host via a
hypercall, giving host virtio-{vdec, video} enough information to
identify the buffer.
This solution is entirely userspace -- we can probably come up with
something in kernel space [generate_random_uuid()] if need be. We
only need two universal IDs: {device ID, buffer ID}.
> On Wed, Nov 6, 2019 at 2:28 PM Geoffrey McRae <geoff@hostfission.com> wrote:
> The entire point of this for our purposes is due to the fact that we can
> not allocate the buffer, it's either provided by the GPU driver or
> DirectX. If virtio-gpu were to allocate the buffer we might as well
> forget
> all this and continue using the ivshmem device.
We have a similar problem with closed source drivers. As @lfy
mentioned, it's possible to map memory directory into virtio-gpu's PCI
bar and it's actually a planned feature. Would that work for your use
case?
next prev parent reply other threads:[~2019-11-12 0:54 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 10:54 guest / host buffer sharing Gerd Hoffmann
2019-11-05 11:35 ` Geoffrey McRae
2019-11-06 6:24 ` Gerd Hoffmann
2019-11-06 8:36 ` David Stevens
2019-11-06 12:41 ` Gerd Hoffmann
2019-11-06 22:28 ` Geoffrey McRae
2019-11-07 6:48 ` Gerd Hoffmann
2019-11-20 12:13 ` Tomasz Figa
2019-11-20 21:41 ` Geoffrey McRae
2019-11-21 5:51 ` Tomasz Figa
2019-12-04 22:22 ` Dylan Reid
2019-12-11 5:08 ` David Stevens
2019-12-11 9:26 ` Gerd Hoffmann
2019-12-11 16:05 ` [virtio-dev] " Enrico Granata
2019-12-12 6:40 ` David Stevens
2019-12-12 9:41 ` Gerd Hoffmann
2019-12-12 12:26 ` David Stevens
2019-12-12 13:30 ` Gerd Hoffmann
2019-12-13 3:21 ` David Stevens
2019-12-16 13:47 ` Gerd Hoffmann
2019-12-17 12:59 ` David Stevens
2019-11-06 8:43 ` Stefan Hajnoczi
2019-11-06 9:51 ` Gerd Hoffmann
2019-11-06 10:10 ` [virtio-dev] " Dr. David Alan Gilbert
2019-11-07 11:11 ` Gerd Hoffmann
2019-11-07 11:16 ` Dr. David Alan Gilbert
2019-11-08 6:45 ` Gerd Hoffmann
2019-11-06 11:46 ` Stefan Hajnoczi
2019-11-06 12:50 ` Gerd Hoffmann
2019-11-07 12:10 ` Stefan Hajnoczi
2019-11-08 7:22 ` Gerd Hoffmann
2019-11-08 7:35 ` Stefan Hajnoczi
2019-11-09 1:41 ` Stéphane Marchesin
2019-11-09 10:12 ` Stefan Hajnoczi
2019-11-09 11:16 ` Tomasz Figa
2019-11-09 12:08 ` Stefan Hajnoczi
2019-11-09 15:12 ` Tomasz Figa
2019-11-18 10:20 ` Stefan Hajnoczi
2019-11-20 10:11 ` Tomasz Figa
[not found] ` <CAEkmjvU8or7YT7CCBe7aUx-XQ3yJpUrY4CfBOnqk7pUH9d9RGQ@mail.gmail.com>
2019-11-20 11:58 ` Tomasz Figa
2019-11-20 12:11 ` Tomasz Figa
2019-11-11 3:04 ` David Stevens
2019-11-11 15:36 ` [virtio-dev] " Liam Girdwood
2019-11-12 0:54 ` Gurchetan Singh [this message]
2019-11-12 13:56 ` Liam Girdwood
2019-11-12 22:55 ` Gurchetan Singh
2019-11-19 15:31 ` Liam Girdwood
2019-11-20 0:42 ` Gurchetan Singh
2019-11-20 9:53 ` Gerd Hoffmann
2019-11-25 16:46 ` Liam Girdwood
2019-11-27 7:58 ` Gerd Hoffmann
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