[PATCH] drm/amdgpu: clear set_q_mode_offs when VM changed

[Yin, ZhenGuo (Chris)]

[AMD Official Use Only - General]

Yeah, I agree.  But I have no idea which place is better.

Best,
Zhenguo
Cloud-GPU Core team, SRDC

-----Original Message-----
From: Koenig, Christian <Christian.Koenig at amd.com>
Sent: Tuesday, April 2, 2024 4:14 PM
To: Yin, ZhenGuo (Chris) <ZhenGuo.Yin at amd.com>; amd-gfx at lists.freedesktop.org
Cc: Deucher, Alexander <Alexander.Deucher at amd.com>
Subject: Re: [PATCH] drm/amdgpu: clear set_q_mode_offs when VM changed

Am 02.04.24 um 08:37 schrieb ZhenGuo Yin:
> [Why]
> set_q_mode_offs don't get cleared after GPU reset, nexting SET_Q_MODE
> packet to init shadow memory will be skiped, hence there has a page fault.
>
> [How]
> VM flush is needed after GPU reset, clear set_q_mode_offs when
> emitting VM flush.
>
> Fixes: 8dad9c062355 ("drm/amdgpu: workaround to avoid SET_Q_MODE
> packets v2")
> Signed-off-by: ZhenGuo Yin <zhenguo.yin at amd.com>

Good catch, yeah it probably doesn't make much sense to execute this after a VM flush.

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> index 7a906318e451..c11c6299711e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v11_0.c
> @@ -5465,6 +5465,7 @@ static void gfx_v11_0_ring_emit_vm_flush(struct amdgpu_ring *ring,
>       /* Make sure that we can't skip the SET_Q_MODE packets when the VM
>        * changed in any way.
>        */
> +     ring->set_q_mode_offs = 0;
>       ring->set_q_mode_ptr = NULL;
>   }
>