Perfect! I can confirm it resolves the issue as well, thank you very much. Have a great day, Alejandro Sior. On Fri, 11 Sep 2020 at 07:58, Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> wrote: > > On 2020.09.08 20:11:21 +0200, Alejandro Sior wrote: > > In the function intel_vgpu_reg_rw_edid of kvmgt.c, pos can be equal > > to NULL for GPUs that do not properly support EDID. In those cases, when > > pos gets passed to the handle_edid functions, it gets added a short offset > > then it's dereferenced in memcpy's, leading to NULL pointer > > dereference kernel oops. > > > > More concretely, that kernel oops renders some Broadwell GPUs users > > unable to set up virtual machines with virtual GPU passthrough (virtual > > machines hang indefinitely when trying to make use of the virtual GPU), > > and make them unable to remove the virtual GPUs once the kernel oops has > > happened (it hangs indefinitely, and notably too when the kernel tries to > > shutdown). The issues that this causes and steps to reproduce are > > discussed in more details in this github issue post: > > https://github.com/intel/gvt-linux/issues/170#issuecomment-685806160 > > > > Check if pos is equal to NULL, and if it is, set ret to a negative > > value, making the module simply indicate that the access to EDID region > > has failed, without any fatal repercussion. > > > > Signed-off-by: Alejandro Sior <aho@xxxxxxx> > > > > --- > > Changes in v2: > > - removed middle name of author to comply with git name > > - rephrased the patch description with imperative phrasing > > - removed useless paragraph > > - made a paragraph more concise > > - fixed typos > > - made individual lines shorter than 75 chars > > > > drivers/gpu/drm/i915/gvt/kvmgt.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c > > index ad8a9df49f29..49163363ba4a 100644 > > --- a/drivers/gpu/drm/i915/gvt/kvmgt.c > > +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c > > @@ -557,7 +557,9 @@ static size_t intel_vgpu_reg_rw_edid(struct intel_vgpu *vgpu, char *buf, > > (struct vfio_edid_region *)kvmgt_vdev(vgpu)->region[i].data; > > loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK; > > > > - if (pos < region->vfio_edid_regs.edid_offset) { > > + if (pos == NULL) { > > + ret = -EINVAL; > > + } else if (pos < region->vfio_edid_regs.edid_offset) { > > ret = handle_edid_regs(vgpu, region, buf, count, pos, iswrite); > > } else { > > pos -= EDID_BLOB_OFFSET; > > Thanks for reporting this! Sorry that we failed to do sanity validation on older > platform when enabling vfio edid function for all platform. > > Could you try below one to see if it fixes your problem? Instead of refusing > possible read of edid, this fixes port number for BDW. > > From d5d9304b6bfdc31356fd2feb1ddbbf28073fe3d4 Mon Sep 17 00:00:00 2001 > From: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> > Date: Fri, 11 Sep 2020 13:50:20 +0800 > Subject: [PATCH] drm/i915/gvt: Fix port number for BDW on EDID region setup > > Current BDW virtual display port is initialized as PORT_B, so need > to use same port for VFIO EDID region, otherwise invalid EDID blob > pointer is assigned. > > Fixes: 0178f4ce3c3b ("drm/i915/gvt: Enable vfio edid for all GVT supported platform") > Signed-off-by: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/gvt/vgpu.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/gvt/vgpu.c b/drivers/gpu/drm/i915/gvt/vgpu.c > index 8fa9b31a2484..f6d7e33c7099 100644 > --- a/drivers/gpu/drm/i915/gvt/vgpu.c > +++ b/drivers/gpu/drm/i915/gvt/vgpu.c > @@ -368,6 +368,7 @@ void intel_gvt_destroy_idle_vgpu(struct intel_vgpu *vgpu) > static struct intel_vgpu *__intel_gvt_create_vgpu(struct intel_gvt *gvt, > struct intel_vgpu_creation_params *param) > { > + struct drm_i915_private *dev_priv = gvt->gt->i915; > struct intel_vgpu *vgpu; > int ret; > > @@ -436,7 +437,10 @@ static struct intel_vgpu *__intel_gvt_create_vgpu(struct intel_gvt *gvt, > if (ret) > goto out_clean_sched_policy; > > - ret = intel_gvt_hypervisor_set_edid(vgpu, PORT_D); > + if (IS_BROADWELL(dev_priv)) > + ret = intel_gvt_hypervisor_set_edid(vgpu, PORT_B); > + else > + ret = intel_gvt_hypervisor_set_edid(vgpu, PORT_D); > if (ret) > goto out_clean_sched_policy; > > -- > 2.28.0 > > > > -- > > $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
