On 8/12/26 09:14, Yifan Zhang wrote:
> From: Prerona Ghosh <[email protected]>
>
> DMA-buf imports are created unbound and land on the VM idle list, so
> neither amdgpu_vm_validate() nor amdgpu_userq_bo_validate() ever binds
> them. Only the BO list of a command submission does, and a VM using user
> queues never runs amdgpu_cs. AMDGPU_GEM_VA then programs PTEs from a
> TTM_PL_SYSTEM resource, i.e. without AMDGPU_PTE_VALID, and the first GPU
> access faults.
>
> Validate imports in amdgpu_gem_object_open() instead, while the BO is
> already reserved by the drm_exec context. Graphics and compute VMs now
> follow the same rule, and a BO that cannot be bound fails the ioctl
> rather than handing out a handle that only maps to faulting PTEs.
>
> v3: validate inside amdgpu_gem_object_open (Christian)
>
> Signed-off-by: Prerona Ghosh <[email protected]>
> Signed-off-by: Yifan Zhang <[email protected]>
> Assisted-by: Claude:claude-opus-5.0
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index f754a4a3a1c2..261218cb57a6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -271,6 +271,20 @@ static int amdgpu_gem_object_open(struct drm_gem_object
> *obj,
> ++bo_va->ref_count;
> }
>
> + /* Imports are created unbound and land on the VM idle list, so neither
> + * amdgpu_vm_validate() nor an amdgpu_cs BO list ever binds them for a
> + * VM that submits through user queues. AMDGPU_GEM_VA would then program
> + * PTEs from a TTM_PL_SYSTEM resource, i.e. without AMDGPU_PTE_VALID.
> + */
> + if (drm_gem_is_imported(obj)) {
> + struct ttm_operation_ctx ctx = { false, false };
> +
> + amdgpu_bo_placement_from_domain(abo, abo->allowed_domains);
> + r = ttm_bo_validate(&abo->tbo, &abo->placement, &ctx);
> + if (r)
> + goto out_unlock;
Taking a look inside amdgpu_evf_mgr_attach_fence() we already have a validation
there for the exact same reason:
if (!dma_fence_is_signaled(ev_fence)) {
amdgpu_bo_placement_from_domain(bo, bo->allowed_domains);
ret = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
if (!ret)
dma_resv_add_fence(resv, ev_fence,
DMA_RESV_USAGE_BOOKKEEP);
} else {
ret = 0;
}
So something doesn't seem to work correctly here.
Can you keep investigating why that doesn't seem to work for imported DMA-bufs?
Thanks,
Christian.
> + }
> +
> drm_exec_fini(&exec);
>
> /* Validate and add eviction fence to DMABuf imports with dynamic
