[PATCH 1/3] drm/amdgpu: Add userptr bo support for mGPUs when iommu is on

[Christian König]

Am 04.04.23 um 11:56 schrieb Shane Xiao:
> For userptr bo with iommu on, multiple GPUs use same system
> memory dma mapping address when both bo_adev and adev in identity
> mode or in the same iommu group.

WTF? Userptr BOs are not allowed to be exported/imported between 
different GPUs.

So how can the same userptr BO be used on different GPUs?

Regards,
Christian.

>
> Signed-off-by: Shane Xiao <shane.xiao at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index e7403f8e4eba..33cda358cb9e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -804,11 +804,11 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
>   			 va + bo_size, vm);
>   
>   		if ((adev == bo_adev && !(mem->alloc_flags & KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP)) ||
> -		    (amdgpu_ttm_tt_get_usermm(mem->bo->tbo.ttm) && adev->ram_is_direct_mapped) ||
> -		    same_hive) {
> +		    (amdgpu_ttm_tt_get_usermm(mem->bo->tbo.ttm) && ((adev->ram_is_direct_mapped && bo_adev->ram_is_direct_mapped) ||
> +			adev->dev->iommu_group == bo_adev->dev->iommu_group)) || same_hive){
>   			/* Mappings on the local GPU, or VRAM mappings in the
> -			 * local hive, or userptr mapping IOMMU direct map mode
> -			 * share the original BO
> +			 * local hive, or userptr mapping in the same dma
> +			 * address space share the original BO
>   			 */
>   			attachment[i]->type = KFD_MEM_ATT_SHARED;
>   			bo[i] = mem->bo;