Re: [PATCH 6/8] drm/amdgpu: stop reserving VMIDs to enforce isolation

[SRINIVASAN SHANMUGAM <srinivasan.shanmugam@xxxxxxx>]

On 3/7/2025 7:18 PM, Christian König wrote:
> That was quite troublesome for gang submit. Completely drop this
> approach and enforce the isolation separately.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c  |  2 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c |  9 +--------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c | 11 +++--------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ids.h |  3 +--
>   4 files changed, 6 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> index 2ce0c6a152a6..4375e5019418 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> @@ -1111,7 +1111,7 @@ static int amdgpu_cs_vm_handling(struct amdgpu_cs_parser *p)
>   			struct drm_gpu_scheduler *sched = entity->rq->sched;
>   			struct amdgpu_ring *ring = to_amdgpu_ring(sched);
>   
> -			if (amdgpu_vmid_uses_reserved(adev, vm, ring->vm_hub))
> +			if (amdgpu_vmid_uses_reserved(vm, ring->vm_hub))
>   				return -EINVAL;
>   		}
>   	}
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> index a194bf3347cb..9e5f6b11d923 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> @@ -1665,15 +1665,8 @@ static ssize_t amdgpu_gfx_set_enforce_isolation(struct device *dev,
>   	}
>   
>   	mutex_lock(&adev->enforce_isolation_mutex);
> -	for (i = 0; i < num_partitions; i++) {
> -		if (adev->enforce_isolation[i] && !partition_values[i])
> -			/* Going from enabled to disabled */
> -			amdgpu_vmid_free_reserved(adev, AMDGPU_GFXHUB(i));
> -		else if (!adev->enforce_isolation[i] && partition_values[i])
> -			/* Going from disabled to enabled */
> -			amdgpu_vmid_alloc_reserved(adev, AMDGPU_GFXHUB(i));
> +	for (i = 0; i < num_partitions; i++)
>   		adev->enforce_isolation[i] = partition_values[i];
> -	}
>   	mutex_unlock(&adev->enforce_isolation_mutex);
>   
>   	amdgpu_mes_update_enforce_isolation(adev);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
> index 92ab821afc06..4c4e087230ac 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c
> @@ -411,7 +411,7 @@ int amdgpu_vmid_grab(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
>   	if (r || !idle)
>   		goto error;
>   
> -	if (amdgpu_vmid_uses_reserved(adev, vm, vmhub)) {
> +	if (amdgpu_vmid_uses_reserved(vm, vmhub)) {
>   		r = amdgpu_vmid_grab_reserved(vm, ring, job, &id, fence);
>   		if (r || !id)

Any Null checks here, needs to be considered?

if fence was expected to be valid after a failed call
        if (fence) {
            dma_fence_put(fence);
        }

>   			goto error;
> @@ -464,19 +464,14 @@ int amdgpu_vmid_grab(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
>   
>   /*
>    * amdgpu_vmid_uses_reserved - check if a VM will use a reserved VMID
> - * @adev: amdgpu_device pointer
>    * @vm: the VM to check
>    * @vmhub: the VMHUB which will be used
>    *
>    * Returns: True if the VM will use a reserved VMID.
>    */
> -bool amdgpu_vmid_uses_reserved(struct amdgpu_device *adev,
> -			       struct amdgpu_vm *vm, unsigned int vmhub)
> +bool amdgpu_vmid_uses_reserved(struct amdgpu_vm *vm, unsigned int vmhub)
>   {
> -	return vm->reserved_vmid[vmhub] ||
> -		(adev->enforce_isolation[(vm->root.bo->xcp_id != AMDGPU_XCP_NO_PARTITION) ?
> -					 vm->root.bo->xcp_id : 0] &&
> -		 AMDGPU_IS_GFXHUB(vmhub));
> +	return vm->reserved_vmid[vmhub];
>   }
>   
>   int amdgpu_vmid_alloc_reserved(struct amdgpu_device *adev,
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.h
> index 4012fb2dd08a..240fa6751260 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.h
> @@ -78,8 +78,7 @@ void amdgpu_pasid_free_delayed(struct dma_resv *resv,
>   
>   bool amdgpu_vmid_had_gpu_reset(struct amdgpu_device *adev,
>   			       struct amdgpu_vmid *id);
> -bool amdgpu_vmid_uses_reserved(struct amdgpu_device *adev,
> -			       struct amdgpu_vm *vm, unsigned int vmhub);
> +bool amdgpu_vmid_uses_reserved(struct amdgpu_vm *vm, unsigned int vmhub);
>   int amdgpu_vmid_alloc_reserved(struct amdgpu_device *adev,
>   				unsigned vmhub);
>   void amdgpu_vmid_free_reserved(struct amdgpu_device *adev,