[PATCH] drm/amdgpu: Block MMR_READ IOCTL in reset

[Skvortsov, Victor]

[AMD Official Use Only - AMD Internal Distribution Only]

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>
>
> On Thu, Aug 8, 2024 at 1:48 PM Victor Skvortsov
> <victor.skvortsov at amd.com> wrote:
> >
> > Register access from userspace should be blocked until reset is
> > complete.
>
> While you are at it, you should protect AMDGPU_INFO_SENSOR as well.
> That queries PMFW which doesn't make sense during reset.  A few minor
> comments below as well.

In general, all PMFW queries are already blocked by pm.dpm_enabled flag. This flag is toggled off in pre_asic_reset, so generally I don't think it will be a problem. Only edge cases I can think of is GFX clock gating that is setup later in hw_resume sequence. But I don't think it warrants this lock.

>
> >
> > Signed-off-by: Victor Skvortsov <victor.skvortsov at amd.com>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 44
> > ++++++++++++++++++-------
> >  1 file changed, 32 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> > index 260cd0ad286d..038b400be437 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> > @@ -778,6 +778,7 @@ int amdgpu_info_ioctl(struct drm_device *dev, void
> *data, struct drm_file *filp)
> >                                     ? -EFAULT : 0;
> >         }
> >         case AMDGPU_INFO_READ_MMR_REG: {
> > +               int ret = 0;
> >                 unsigned int n, alloc_size;
> >                 uint32_t *regs;
> >                 unsigned int se_num = (info->read_mmr_reg.instance >>
> > @@ -787,24 +788,39 @@ int amdgpu_info_ioctl(struct drm_device *dev,
> void *data, struct drm_file *filp)
> >                                    AMDGPU_INFO_MMR_SH_INDEX_SHIFT) &
> >                                   AMDGPU_INFO_MMR_SH_INDEX_MASK;
> >
> > +               if (!down_read_trylock(&adev->reset_domain->sem))
> > +                       return -ENOENT;
> > +
> >                 /* set full masks if the userspace set all bits
> >                  * in the bitfields
> >                  */
> > -               if (se_num == AMDGPU_INFO_MMR_SE_INDEX_MASK)
> > +               if (se_num == AMDGPU_INFO_MMR_SE_INDEX_MASK) {
> >                         se_num = 0xffffffff;
> > -               else if (se_num >= AMDGPU_GFX_MAX_SE)
> > -                       return -EINVAL;
> > -               if (sh_num == AMDGPU_INFO_MMR_SH_INDEX_MASK)
> > +               }
> > +               else if (se_num >= AMDGPU_GFX_MAX_SE) {
>
> Kernel coding style.  Put the } on the same line as the else.
>
> > +                       ret = -EINVAL;
> > +                       goto out;
> > +               }
> > +
> > +               if (sh_num == AMDGPU_INFO_MMR_SH_INDEX_MASK) {
> >                         sh_num = 0xffffffff;
> > -               else if (sh_num >= AMDGPU_GFX_MAX_SH_PER_SE)
> > -                       return -EINVAL;
> > +               }
> > +               else if (sh_num >= AMDGPU_GFX_MAX_SH_PER_SE) {
>
> Same here.
>
> > +                       ret = -EINVAL;
> > +                       goto out;
> > +               }
> >
> > -               if (info->read_mmr_reg.count > 128)
> > -                       return -EINVAL;
> > +               if (info->read_mmr_reg.count > 128) {
> > +                       ret = -EINVAL;
> > +                       goto out;
> > +               }
> >
> >                 regs = kmalloc_array(info->read_mmr_reg.count, sizeof(*regs),
> GFP_KERNEL);
> > -               if (!regs)
> > -                       return -ENOMEM;
> > +               if (!regs) {
> > +                       ret = -ENOMEM;
> > +                       goto out;
> > +               }
> > +
> >                 alloc_size = info->read_mmr_reg.count * sizeof(*regs);
> >
> >                 amdgpu_gfx_off_ctrl(adev, false); @@ -816,13 +832,17
> > @@ int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct
> drm_file *filp)
> >                                               info->read_mmr_reg.dword_offset + i);
> >                                 kfree(regs);
> >                                 amdgpu_gfx_off_ctrl(adev, true);
> > -                               return -EFAULT;
> > +                               ret = -EFAULT;
> > +                               goto out;
> >                         }
> >                 }
> >                 amdgpu_gfx_off_ctrl(adev, true);
> >                 n = copy_to_user(out, regs, min(size, alloc_size));
> >                 kfree(regs);
> > -               return n ? -EFAULT : 0;
> > +               ret = (n ? -EFAULT : 0);
> > +out:
> > +               up_read(&adev->reset_domain->sem);
> > +               return ret;
> >         }
> >         case AMDGPU_INFO_DEV_INFO: {
> >                 struct drm_amdgpu_info_device *dev_info;
> > --
> > 2.34.1
> >