Re: [PATCH] drm/amd/amdgpu: Avoid writing GMC registers under sriov in gmc9

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 02.11.21 um 11:25 schrieb YuBiao Wang:
> [Why]
> For Vega10, disabling gart of gfxhub and mmhub could mess up KIQ and PSP under sriov mode, and lead to DMAR on host side.
>
> [How]
> Do not call gmc_gart_disable under sriov but keep vram_unpin to avoid
> pin_count leak.

NAK, if you want to do this you should probably avoid the write in the 
low level hardware callbacks and not here.

Christian.

>
> Signed-off-by: YuBiao Wang <YuBiao.Wang@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> index cb82404df534..365059a20ae8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> @@ -1793,14 +1793,13 @@ static void gmc_v9_0_gart_disable(struct amdgpu_device *adev)
>   {
>   	adev->gfxhub.funcs->gart_disable(adev);
>   	adev->mmhub.funcs->gart_disable(adev);
> -	amdgpu_gart_table_vram_unpin(adev);
>   }
>   
>   static int gmc_v9_0_hw_fini(void *handle)
>   {
>   	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
>   
> -	gmc_v9_0_gart_disable(adev);
> +	amdgpu_gart_table_vram_unpin(adev);
>   
>   	if (amdgpu_sriov_vf(adev)) {
>   		/* full access mode, so don't touch any GMC register */
> @@ -1808,6 +1807,7 @@ static int gmc_v9_0_hw_fini(void *handle)
>   		return 0;
>   	}
>   
> +	gmc_v9_0_gart_disable(adev);
>   	amdgpu_irq_put(adev, &adev->gmc.ecc_irq, 0);
>   	amdgpu_irq_put(adev, &adev->gmc.vm_fault, 0);
>