On Wed, 5 Oct 2022 14:17:17 -0600
Alex Williamson <alex.williamson@xxxxxxxxxx> wrote:
> On Thu, 29 Sep 2022 14:48:35 -0300
> Jason Gunthorpe <jgg@xxxxxxxxxx> wrote:
>
> > When converting to directly create the vfio_device the mdev driver has to
> > put a vfio_register_emulated_iommu_dev() in the probe() and a pairing
> > vfio_unregister_group_dev() in the remove.
> >
> > This was missed for gvt, add it.
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Fixes: 978cf586ac35 ("drm/i915/gvt: convert to use vfio_register_emulated_iommu_dev")
> > Reported-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/gvt/kvmgt.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > Should go through Alex's tree.
> >
> > diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> > index 41bba40feef8f4..9003145adb5a93 100644
> > --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> > +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> > @@ -1615,6 +1615,7 @@ static void intel_vgpu_remove(struct mdev_device *mdev)
> > if (WARN_ON_ONCE(vgpu->attached))
> > return;
Actually, what's the purpose of this ^^^^ ?
We can't have a .remove callback that does nothing, this breaks
removing the device while it's in use. Once we have the
vfio_unregister_group_dev() fix below, we'll block until the device is
unused, at which point vgpu->attached becomes false. Unless I'm
missing something, I think we should also follow-up with a patch to
remove that bogus warn-on branch, right? Thanks,
Alex
> >
> > + vfio_unregister_group_dev(&vgpu->vfio_device);
> > vfio_put_device(&vgpu->vfio_device);
> > }
> >
> >
> > base-commit: c72e0034e6d4c36322d958b997d11d2627c6056c
>
> This is marked for stable, but I think the stable backport for
> existing kernels is actually:
>
> diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> index e3cd58946477..de89946c4817 100644
> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> @@ -1595,6 +1595,9 @@ static void intel_vgpu_remove(struct mdev_device *mdev)
>
> if (WARN_ON_ONCE(vgpu->attached))
> return;
> +
> + vfio_unregister_group_dev(&vgpu->vfio_device);
> + vfio_uninit_group_dev(&vgpu->vfio_device);
> intel_gvt_destroy_vgpu(vgpu);
> }
