[PATCH libdrm 3/4] amdgpu: add a function to find bo by cpu mapping

[Christian König]

Am 07.08.2018 um 09:26 schrieb Junwei Zhang:
> Userspace needs to know if the user memory is from BO or malloc.
>
> Signed-off-by: Junwei Zhang <Jerry.Zhang at amd.com>
> ---
>   amdgpu/amdgpu.h    | 23 +++++++++++++++++++++++
>   amdgpu/amdgpu_bo.c | 34 ++++++++++++++++++++++++++++++++++
>   2 files changed, 57 insertions(+)
>
> diff --git a/amdgpu/amdgpu.h b/amdgpu/amdgpu.h
> index be83b45..a8c353c 100644
> --- a/amdgpu/amdgpu.h
> +++ b/amdgpu/amdgpu.h
> @@ -678,6 +678,29 @@ int amdgpu_create_bo_from_user_mem(amdgpu_device_handle dev,
>   				    amdgpu_bo_handle *buf_handle);
>   
>   /**
> + * Validate if the user memory comes from BO
> + *
> + * \param dev - [in] Device handle. See #amdgpu_device_initialize()
> + * \param cpu - [in] CPU address of user allocated memory which we
> + * want to map to GPU address space (make GPU accessible)
> + * (This address must be correctly aligned).
> + * \param size - [in] Size of allocation (must be correctly aligned)
> + * \param buf_handle - [out] Buffer handle for the userptr memory
> + * if the user memory is not from BO, the buf_handle will be NULL.
> + * \param offset_in_bo - [out] offset in this BO for this user memory
> + *
> + *
> + * \return   0 on success\n
> + *          <0 - Negative POSIX Error code
> + *
> +*/
> +int amdgpu_find_bo_by_cpu_mapping(amdgpu_device_handle dev,
> +				  void *cpu,
> +				  uint64_t size,
> +				  amdgpu_bo_handle *buf_handle,
> +				  uint64_t *offset_in_bo);
> +
> +/**
>    * Free previosuly allocated memory
>    *
>    * \param   dev	       - \c [in] Device handle. See #amdgpu_device_initialize()
> diff --git a/amdgpu/amdgpu_bo.c b/amdgpu/amdgpu_bo.c
> index b24e698..a631050 100644
> --- a/amdgpu/amdgpu_bo.c
> +++ b/amdgpu/amdgpu_bo.c
> @@ -529,6 +529,40 @@ int amdgpu_bo_wait_for_idle(amdgpu_bo_handle bo,
>   	}
>   }
>   
> +int amdgpu_find_bo_by_cpu_mapping(amdgpu_device_handle dev,
> +				  void *cpu,
> +				  uint64_t size,
> +				  amdgpu_bo_handle *buf_handle,
> +				  uint64_t *offset_in_bo)
> +{
> +	int i;
> +	struct amdgpu_bo *bo;
> +
> +	if (cpu == NULL || size == 0)
> +		return -EINVAL;
> +
> +	pthread_mutex_lock(&dev->bo_table_mutex);
> +	for (i = 0; i <= dev->bo_handles.max_key; i++) {
> +		bo = handle_table_lookup(&dev->bo_handles, i);
> +		if (!bo || !bo->cpu_ptr || size > bo->alloc_size)
> +			continue;
> +		if (cpu >= bo->cpu_ptr && cpu < (bo->cpu_ptr + bo->alloc_size))
> +			break;
> +	}
> +	pthread_mutex_unlock(&dev->bo_table_mutex);
> +
> +	if (i <= dev->bo_handles.max_key) {

This check needs to be inside the lock or otherwise max_key could change 
at the same time as you do the check.

Apart from that this looks good to me if you can live with the extra 
overhead of scanning all BOs.

Regards,
Christian.

> +		atomic_inc(&bo->refcount);
> +		*buf_handle = bo;
> +		*offset_in_bo = cpu - bo->cpu_ptr;
> +	} else {
> +		*buf_handle = NULL;
> +		*offset_in_bo = 0;
> +	}
> +
> +	return 0;
> +}
> +
>   int amdgpu_create_bo_from_user_mem(amdgpu_device_handle dev,
>   				    void *cpu,
>   				    uint64_t size,