Re: [PATCH] drm/amdgpu: Fix VM clean check method

["Christian König" <ckoenig.leichtzumerken-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Am 30.04.19 um 16:18 schrieb Trigger Huang:
> amdgpu_vm_make_compute is used to turn a GFX VM into a compute VM,
> the prerequisite is this VM is clean. Let's check if some page tables
> are already filled , while not check if some mapping is already made.
>
> Signed-off-by: Trigger Huang <Trigger.Huang@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 36 +++++++++++++++++++++++++++++++++-
>   1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 56d838f..6752d4c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2755,6 +2755,40 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
>   }
>   
>   /**
> + * amdgpu_vm_check_clean_reserved - check if a VM is clean
> + *
> + * @adev: amdgpu_device pointer
> + * @vm: the VM to check
> + *
> + * check all entries of the root PD, if any subsequent PDs are allocated,
> + * it means there are page table creating and filling, and is no a clean
> + * VM
> + *
> + * Returns:
> + *	0 if this VM is clean
> + */
> +static int amdgpu_vm_check_clean_reserved(struct amdgpu_device *adev,
> +	struct amdgpu_vm *vm)
> +{
> +	int ret = 0;
> +
> +	if (vm->root.entries) {

Use an early return here.

> +		unsigned int i = 0;
> +		enum amdgpu_vm_level l = adev->vm_manager.root_level;
> +		unsigned int entries = amdgpu_vm_num_entries(adev, l);

And coding style usually uses reverse x-mas tree, e.g. stuff like "i" or 
"ret" last.

Christian.

> +
> +		for (i = 0; i < entries; i++) {
> +			if (vm->root.entries[i].base.bo) {
> +				ret = -EINVAL;
> +				break;
> +			}
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +/**
>    * amdgpu_vm_make_compute - Turn a GFX VM into a compute VM
>    *
>    * @adev: amdgpu_device pointer
> @@ -2784,7 +2818,7 @@ int amdgpu_vm_make_compute(struct amdgpu_device *adev, struct amdgpu_vm *vm, uns
>   		return r;
>   
>   	/* Sanity checks */
> -	if (!RB_EMPTY_ROOT(&vm->va.rb_root) || vm->root.entries) {
> +	if (amdgpu_vm_check_clean_reserved(adev, vm)) {
>   		r = -EINVAL;
>   		goto unreserve_bo;
>   	}

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