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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: References: <20260428194450.518296-1-slp@redhat.com> <20260428194450.518296-3-slp@redhat.com> Date: Mon, 13 Jul 2026 13:19:20 +0200 Message-ID: <87v7ajyw5j.fsf@alyssa.is> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org 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 7/1/26 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 >>=20 >> 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. >>=20 >> https://issuetracker.google.com/issues/529852979 >>=20 >>> --- >>> 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/v= irtio/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 *v= gdev, >>> 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. 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? --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYKAB0WIQRV/neXydHjZma5XLJbRZGEIw/wogUCalTJuAAKCRBbRZGEIw/w olSQAP9qzYChgBOtNgtwj23gpSHyaReaZOMLJq5xNMgU5uryywEA88prn6UVr8ZA o6rYMiGcL4mLSwcdy71KOyCnjbegdw0= =IPYo -----END PGP SIGNATURE----- --=-=-=--