[PATCH 2/2] drm/amdgpu: Synchronize after mapping into a compute VM

[Christian König]

Am 25.02.23 um 00:36 schrieb Felix Kuehling:
> Compute VMs use user mode queues for command submission. They cannot use
> a CS ioctl to synchronize with pending PTE updates and flush TLBs. Do
> this synchronization in amdgpu_gem_va_ioctl for compute VMs.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 16 ++++++++++++++--
>   1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index 6936cd63df42..7de5057c40ec 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -601,7 +601,7 @@ int amdgpu_gem_metadata_ioctl(struct drm_device *dev, void *data,
>   static void amdgpu_gem_va_update_vm(struct amdgpu_device *adev,
>   				    struct amdgpu_vm *vm,
>   				    struct amdgpu_bo_va *bo_va,
> -				    uint32_t operation)
> +				    uint32_t operation, uint32_t flags)
>   {
>   	int r;
>   
> @@ -620,6 +620,18 @@ static void amdgpu_gem_va_update_vm(struct amdgpu_device *adev,
>   	}
>   
>   	r = amdgpu_vm_update_pdes(adev, vm, false);
> +	if (r)
> +		goto error;
> +
> +	if (vm->is_compute_context) {
> +		if (bo_va->last_pt_update)
> +			r = dma_fence_wait(bo_va->last_pt_update, true);
> +		if (!r && vm->last_update)
> +			r = dma_fence_wait(vm->last_update, true);
> +		if (!r)
> +			r = amdgpu_amdkfd_flush_tlb(adev, vm,
> +			    TLB_FLUSH_LEGACY);
> +	}

Mhm, that's not really something we can do here. The GEM VA IOCTL is 
supposed to be async and never block.

Can we do that on the KFD side in some IOCTL instead?

Regards,
Christian.

>   
>   error:
>   	if (r && r != -ERESTARTSYS)
> @@ -789,7 +801,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
>   	}
>   	if (!r && !(args->flags & AMDGPU_VM_DELAY_UPDATE) && !amdgpu_vm_debug)
>   		amdgpu_gem_va_update_vm(adev, &fpriv->vm, bo_va,
> -					args->operation);
> +					args->operation, args->flags);
>   
>   error_backoff:
>   	ttm_eu_backoff_reservation(&ticket, &list);