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: Tue, 12 Nov 2019 14:55:49 -0800 [thread overview]
Message-ID: <CAAfnVB=F+HeQrrn23c=rZeOa5BfHo=9ArcG--gLf87gqBXfZ9A@mail.gmail.com> (raw)
In-Reply-To: <4a5dd822e86757f004d04af62fb7dd35ba75392d.camel@linux.intel.com>
On Tue, Nov 12, 2019 at 5:56 AM Liam Girdwood
<liam.r.girdwood@linux.intel.com> wrote:
>
> On Mon, 2019-11-11 at 16:54 -0800, Gurchetan Singh wrote:
> > 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.
> >
>
> Audio also needs to share buffers with firmware running on DSPs.
>
> > 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}.
> >
>
> I need something where I can take a guest buffer and then convert it to
> physical scatter gather page list. I can then either pass the SG page
> list to the DSP firmware (for DMAC IP programming) or have the host
> driver program the DMAC directly using the page list (who programs DMAC
> depends on DSP architecture).
So you need the HW address space from a guest allocation? Would your
allocation hypercalls use something like the virtio_gpu_mem_entry
(virtio_gpu.h) and the draft virtio_video_mem_entry (draft)?
struct {
__le64 addr;
__le32 length;
__le32 padding;
};
/* VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING */
struct virtio_gpu_resource_attach_backing {
struct virtio_gpu_ctrl_hdr hdr;
__le32 resource_id;
__le32 nr_entries;
*struct struct virtio_gpu_mem_entry */
};
struct virtio_video_mem_entry {
__le64 addr;
__le32 length;
__u8 padding[4];
};
struct virtio_video_resource_attach_backing {
struct virtio_video_ctrl_hdr hdr;
__le32 resource_id;
__le32 nr_entries;
};
>
> DSP FW has no access to userspace so we would need some additional API
> on top of DMA_BUF_SET_NAME etc to get physical hardware pages ?
The dma-buf api currently can share guest memory sg-lists.
>
> Liam
>
>
>
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>
next prev parent reply other threads:[~2019-11-12 22:56 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
2019-11-12 13:56 ` Liam Girdwood
2019-11-12 22:55 ` Gurchetan Singh [this message]
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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