[PATCH] drm/amdgpu: Add missing locking for MES API calls

[Joshi, Mukul]

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Russell, Kent <Kent.Russell at amd.com>
> Sent: Thursday, June 6, 2024 12:57 PM
> To: Joshi, Mukul <Mukul.Joshi at amd.com>; amd-gfx at lists.freedesktop.org
> Cc: Kuehling, Felix <Felix.Kuehling at amd.com>; Deucher, Alexander
> <Alexander.Deucher at amd.com>; Joshi, Mukul <Mukul.Joshi at amd.com>
> Subject: RE: [PATCH] drm/amdgpu: Add missing locking for MES API calls
>
> [AMD Official Use Only - AMD Internal Distribution Only]
>
> > -----Original Message-----
> > From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of
> > Mukul Joshi
> > Sent: Thursday, June 6, 2024 12:51 PM
> > To: amd-gfx at lists.freedesktop.org
> > Cc: Kuehling, Felix <Felix.Kuehling at amd.com>; Deucher, Alexander
> > <Alexander.Deucher at amd.com>; Joshi, Mukul <Mukul.Joshi at amd.com>
> > Subject: [PATCH] drm/amdgpu: Add missing locking for MES API calls
> >
> > Add missing locking at a few places when calling MES APIs to ensure
> > exclusive access to MES queue.
> >
> > Signed-off-by: Mukul Joshi <mukul.joshi at amd.com>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> > index 62edf6328566..df6c067b1dc9 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mes.c
> > @@ -801,7 +801,9 @@ int amdgpu_mes_map_legacy_queue(struct
> > amdgpu_device *adev,
> >       queue_input.mqd_addr = amdgpu_bo_gpu_offset(ring->mqd_obj);
> >       queue_input.wptr_addr = ring->wptr_gpu_addr;
> >
> > +     amdgpu_mes_lock(&adev->mes);
> >       r = adev->mes.funcs->map_legacy_queue(&adev->mes, &queue_input);
> > +     amdgpu_mes_unlock(&adev->mes);
> >       if (r)
> >               DRM_ERROR("failed to map legacy queue\n");
> >
> > @@ -824,7 +826,9 @@ int amdgpu_mes_unmap_legacy_queue(struct
> > amdgpu_device *adev,
> >       queue_input.trail_fence_addr = gpu_addr;
> >       queue_input.trail_fence_data = seq;
> >
> > +     amdgpu_mes_lock(&adev->mes);
> >       r = adev->mes.funcs->unmap_legacy_queue(&adev->mes,
> > &queue_input);
> > +     amdgpu_mes_unlock(&adev->mes);
> >       if (r)
> >               DRM_ERROR("failed to unmap legacy queue\n");
> >
> > @@ -845,11 +849,13 @@ uint32_t amdgpu_mes_rreg(struct
> amdgpu_device
> > *adev, uint32_t reg)
> >               goto error;
> >       }
> >
> > +     amdgpu_mes_lock(&adev->mes);
> >       r = adev->mes.funcs->misc_op(&adev->mes, &op_input);
> >       if (r)
> >               DRM_ERROR("failed to read reg (0x%x)\n", reg);
> >       else
> >               val = *(adev->mes.read_val_ptr);
> > +     amdgpu_mes_unlock(&adev->mes);
> If we're following the pattern, this should go before the if/else block
>
>  Kent

I wanted to make sure read_val_ptr wasn't updated before its value was read.
That's the reason to put the unlock after fetching the read_val_ptr.

Mukul
>
> >
> >  error:
> >       return val;
> > @@ -871,7 +877,9 @@ int amdgpu_mes_wreg(struct amdgpu_device
> *adev,
> >               goto error;
> >       }
> >
> > +     amdgpu_mes_lock(&adev->mes);
> >       r = adev->mes.funcs->misc_op(&adev->mes, &op_input);
> > +     amdgpu_mes_unlock(&adev->mes);
> >       if (r)
> >               DRM_ERROR("failed to write reg (0x%x)\n", reg);
> >
> > @@ -898,7 +906,9 @@ int amdgpu_mes_reg_write_reg_wait(struct
> > amdgpu_device *adev,
> >               goto error;
> >       }
> >
> > +     amdgpu_mes_lock(&adev->mes);
> >       r = adev->mes.funcs->misc_op(&adev->mes, &op_input);
> > +     amdgpu_mes_unlock(&adev->mes);
> >       if (r)
> >               DRM_ERROR("failed to reg_write_reg_wait\n");
> >
> > @@ -923,7 +933,9 @@ int amdgpu_mes_reg_wait(struct amdgpu_device
> > *adev, uint32_t reg,
> >               goto error;
> >       }
> >
> > +     amdgpu_mes_lock(&adev->mes);
> >       r = adev->mes.funcs->misc_op(&adev->mes, &op_input);
> > +     amdgpu_mes_unlock(&adev->mes);
> >       if (r)
> >               DRM_ERROR("failed to reg_write_reg_wait\n");
> >
> > --
> > 2.35.1
>