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Tsirkin" , Eugenio =?utf-8?Q?P=C3=A9rez?= , Xuan Zhuo , linux-kernel@vger.kernel.org, Simona Vetter , Thomas Zimmermann , David Airlie , Gurchetan Singh , Gerd Hoffmann , virtualization@lists.linux.dev, dri-devel@lists.freedesktop.org, Maxime Ripard , Maarten Lankhorst Subject: Re: [PATCH v2 2/3] drm/virtio: honor blob_alignment requirements In-Reply-To: <17764937-21dc-4b4a-8def-e738b361bcd1@collabora.com> References: <20260428194450.518296-1-slp@redhat.com> <20260428194450.518296-3-slp@redhat.com> <87v7ajyw5j.fsf@alyssa.is> <17764937-21dc-4b4a-8def-e738b361bcd1@collabora.com> Date: Wed, 15 Jul 2026 12:13:52 +0200 Message-ID: <87ldbc4l27.fsf@alyssa.is> Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Dmitry Osipenko writes: > On 7/13/26 14:19, Alyssa Ross wrote: >> Dmitry Osipenko writes: >>=20 >>> On 7/1/26 14:10, Alyssa Ross wrote: >>>> On Tue, Apr 28, 2026 at 09:44:49PM +0200, Sergio Lopez wrote: >>>>> If VIRTIO_GPU_F_BLOB_ALIGNMENT has been negotiated, blob size must be >>>>> aligned to blob_alignment. Validate this in verify_blob() so that >>>>> invalid requests are rejected early. >>>>> >>>>> Signed-off-by: Sergio Lopez >>>> >>>> FYI: this change breaks crosvm, which is squatting the 5 and 6 values >>>> of VIRTIO_GPU_F_* with different meanings. I've reported it as a >>>> crosvm bug, so hopefully it can be taken care of there. >>>> >>>> https://issuetracker.google.com/issues/529852979 >>>> >>>>> --- >>>>> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 5 +++++ >>>>> 1 file changed, 5 insertions(+) >>>>> >>>>> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm= /virtio/virtgpu_ioctl.c >>>>> index c33c057365f8..d0c4edf1eaf4 100644 >>>>> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c >>>>> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c >>>>> @@ -489,6 +489,11 @@ static int verify_blob(struct virtio_gpu_device = *vgdev, >>>>> params->size =3D rc_blob->size; >>>>> params->blob =3D true; >>>>> params->blob_flags =3D rc_blob->blob_flags; >>>>> + >>>>> + if (vgdev->has_blob_alignment && >>>>> + !IS_ALIGNED(params->size, vgdev->blob_alignment)) >>>>> + return -EINVAL; >>>>> + >>>>> return 0; >>>>> } >>>>> >>>>> -- >>>>> 2.53.0 >>>>> >>> >>> Thanks for the report. Indeed, crosvm will need to fix its experimental >>> caps. CI will likely run into this problem first once it will update >>> guest to 7.2+ kernel. >>=20 >> I sent >> https://chromium-review.googlesource.com/c/crosvm/crosvm/+/8064741 last >> week but still waiting to hear anything. Do you have any insight into >> whether it's still used / being pursued? > > The GUEST_HANDLE should be used by Android [1]. The FENCE_PASSING > shouldn't be used in production, though don't know for sure. > > Crosvm should bump its experimental defines by +10 to prevent clash with > upstream in future. > > [1] > https://github.com/google/gfxstream/blob/main/host/vulkan/vk_decoder_glob= al_state.cpp#L107 Thanks for the extra info. :) They've agreed to go ahead and remove both of them, so the problem is solved. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQRV/neXydHjZma5XLJbRZGEIw/wogUCalddYAAKCRBbRZGEIw/w orGgAQC/YXYu4X+sdCLEkVpxdPV5ypPiF82l9tUZ4Wd+kuwJqQEA3aMqqCYrmTX3 e4gNsI1wlXn3W9wPHQe7CSogvsTvPQM= =xZq0 -----END PGP SIGNATURE----- --=-=-=--