From: David Stevens <stevensd@chromium.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Jason Wang <jasowang@redhat.com>,
Sumit Semwal <sumit.semwal@linaro.org>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
open list <linux-kernel@vger.kernel.org>,
ML dri-devel <dri-devel@lists.freedesktop.org>,
"open list:VIRTIO GPU DRIVER"
<virtualization@lists.linux-foundation.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
"moderated list:DMA BUFFER SHARING FRAMEWORK"
<linaro-mm-sig@lists.linaro.org>,
virtio-dev@lists.oasis-open.org
Subject: Re: [PATCH v3 4/4] drm/virtio: Support virtgpu exported resources
Date: Mon, 8 Jun 2020 19:36:55 +0900 [thread overview]
Message-ID: <CAD=HUj6kF2JFyC9c0CY5_f-cv6r97501Z2f8D9x0VhQpRen+bw@mail.gmail.com> (raw)
In-Reply-To: <20200608054234-mutt-send-email-mst@kernel.org>
On Mon, Jun 8, 2020 at 6:43 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Fri, May 15, 2020 at 04:26:15PM +0900, David Stevens wrote:
> > > > + if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_UUID)) {
> > > > + vgdev->has_resource_assign_uuid = true;
> > > > + }
> > >
> > >
> > > Just a question: this relies on DMA bufs so I assume it is
> > > not really assumed to work when DMA API is bypassed, right?
> > > Rather than worry what does it mean, how about just
> > > disabling this feature without PLATFORM_DMA for now?
> >
> > By PLATFORM_DMA, do you mean CONFIG_DMA_SHARED_BUFFER?
>
> Sorry, no. I mean VIRTIO_F_IOMMU_PLATFORM which in the
> future will be renamed to VIRTIO_F_PLATFORM_ACCESS.
Shouldn't things work independent of whether or not that feature is
set? If a virtio driver properly uses the dma_buf APIs (which virtgpu
seems to), then that should take care of any mapping/synchronization
related to VIRTIO_F_IOMMU_PLATFORM. If anything, the case where
VIRTIO_F_IOMMU_PLATFORM isn't set is easier, since then we know that
the "the device has same access [sic] to memory addresses supplied to
it as the driver has", according to the specification.
-David
next prev parent reply other threads:[~2020-06-08 10:37 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-11 11:20 [PATCH v3 0/4] Support virtio cross-device resources David Stevens
2020-03-11 11:20 ` [PATCH v3 1/4] dma-buf: add support for virtio exported objects David Stevens
2020-05-13 15:45 ` Daniel Vetter
2020-05-14 2:08 ` David Stevens
2020-05-14 12:28 ` Daniel Vetter
2020-05-14 7:59 ` Gerd Hoffmann
2020-05-14 12:31 ` Daniel Vetter
2020-05-14 8:19 ` David Stevens
2020-05-14 12:30 ` Daniel Vetter
2020-05-15 5:07 ` David Stevens
2020-05-15 14:03 ` Daniel Vetter
2020-05-18 11:17 ` Sumit Semwal
2020-03-11 11:20 ` [PATCH v3 2/4] drm/prime: " David Stevens
2020-03-11 11:20 ` [PATCH v3 3/4] virtio-gpu: add VIRTIO_GPU_F_RESOURCE_UUID feature David Stevens
2020-03-11 11:20 ` [PATCH v3 4/4] drm/virtio: Support virtgpu exported resources David Stevens
2020-05-13 16:34 ` Michael S. Tsirkin
2020-05-15 7:26 ` David Stevens
2020-06-08 9:43 ` Michael S. Tsirkin
2020-06-08 10:36 ` David Stevens [this message]
2020-06-08 15:17 ` Michael S. Tsirkin
2020-03-20 6:48 ` [PATCH v3 0/4] Support virtio cross-device resources Gerd Hoffmann
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