Re: [PATCH 5/6] drm/amdkfd: Import DMABufs for interop through DRM

[Felix Kuehling <felix.kuehling@amd.com>]

On 2023-11-08 18:20, Chen, Xiaogang wrote:
>
> On 11/7/2023 10:58 AM, Felix Kuehling wrote:
>> Use drm_gem_prime_fd_to_handle to import DMABufs for interop. This
>> ensures that a GEM handle is created on import and that obj->dma_buf
>> will be set and remain set as long as the object is imported into KFD.
>>
>> Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h    |  9 ++-
>>   .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  | 64 +++++++++++++------
>>   drivers/gpu/drm/amd/amdkfd/kfd_chardev.c      | 15 ++---
>>   3 files changed, 52 insertions(+), 36 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> index 4caf8cece028..88a0e0734270 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
>> @@ -318,11 +318,10 @@ int 
>> amdgpu_amdkfd_gpuvm_restore_process_bos(void *process_info,
>>                           struct dma_fence **ef);
>>   int amdgpu_amdkfd_gpuvm_get_vm_fault_info(struct amdgpu_device *adev,
>>                             struct kfd_vm_fault_info *info);
>> -int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
>> -                      struct dma_buf *dmabuf,
>> -                      uint64_t va, void *drm_priv,
>> -                      struct kgd_mem **mem, uint64_t *size,
>> -                      uint64_t *mmap_offset);
>> +int amdgpu_amdkfd_gpuvm_import_dmabuf_fd(struct amdgpu_device *adev, 
>> int fd,
>> +                     uint64_t va, void *drm_priv,
>> +                     struct kgd_mem **mem, uint64_t *size,
>> +                     uint64_t *mmap_offset);
>>   int amdgpu_amdkfd_gpuvm_export_dmabuf(struct kgd_mem *mem,
>>                         struct dma_buf **dmabuf);
>>   void amdgpu_amdkfd_debug_mem_fence(struct amdgpu_device *adev);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> index 4bb8b5fd7598..1077de8bced2 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
>> @@ -2006,8 +2006,7 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
>>         /* Free the BO*/
>>       drm_vma_node_revoke(&mem->bo->tbo.base.vma_node, drm_priv);
>> -    if (!mem->is_imported)
>> -        drm_gem_handle_delete(adev->kfd.client.file, mem->gem_handle);
>> +    drm_gem_handle_delete(adev->kfd.client.file, mem->gem_handle);
>
> A minor thing for this patch: I think this is a correction for last 
> patch " Export DMABufs from KFD using GEM handles". mem->gem_handle is 
> created unconditionally at amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu.  
> drm_gem_handle_delete should be put at the lat patch.

This change was intentional. Without this patch, imported DMABufs didn't 
get a GEM handle, so I didn't need to delete one. With this patch, I now 
have a GEM handle for imported BOs, so I delete the GEM handle 
unconditionally.

Regards,
   Felix


>
> Regards
>
> Xiaogang
>
>>       if (mem->dmabuf) {
>>           dma_buf_put(mem->dmabuf);
>>           mem->dmabuf = NULL;
>> @@ -2363,34 +2362,26 @@ int 
>> amdgpu_amdkfd_gpuvm_get_vm_fault_info(struct amdgpu_device *adev,
>>       return 0;
>>   }
>>   -int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
>> -                      struct dma_buf *dma_buf,
>> -                      uint64_t va, void *drm_priv,
>> -                      struct kgd_mem **mem, uint64_t *size,
>> -                      uint64_t *mmap_offset)
>> +static int import_obj_create(struct amdgpu_device *adev,
>> +                 struct dma_buf *dma_buf,
>> +                 struct drm_gem_object *obj,
>> +                 uint64_t va, void *drm_priv,
>> +                 struct kgd_mem **mem, uint64_t *size,
>> +                 uint64_t *mmap_offset)
>>   {
>>       struct amdgpu_vm *avm = drm_priv_to_vm(drm_priv);
>> -    struct drm_gem_object *obj;
>>       struct amdgpu_bo *bo;
>>       int ret;
>>   -    obj = amdgpu_gem_prime_import(adev_to_drm(adev), dma_buf);
>> -    if (IS_ERR(obj))
>> -        return PTR_ERR(obj);
>> -
>>       bo = gem_to_amdgpu_bo(obj);
>>       if (!(bo->preferred_domains & (AMDGPU_GEM_DOMAIN_VRAM |
>> -                    AMDGPU_GEM_DOMAIN_GTT))) {
>> +                    AMDGPU_GEM_DOMAIN_GTT)))
>>           /* Only VRAM and GTT BOs are supported */
>> -        ret = -EINVAL;
>> -        goto err_put_obj;
>> -    }
>> +        return -EINVAL;
>>         *mem = kzalloc(sizeof(struct kgd_mem), GFP_KERNEL);
>> -    if (!*mem) {
>> -        ret = -ENOMEM;
>> -        goto err_put_obj;
>> -    }
>> +    if (!*mem)
>> +        return -ENOMEM;
>>         ret = drm_vma_node_allow(&obj->vma_node, drm_priv);
>>       if (ret)
>> @@ -2440,8 +2431,41 @@ int amdgpu_amdkfd_gpuvm_import_dmabuf(struct 
>> amdgpu_device *adev,
>>       drm_vma_node_revoke(&obj->vma_node, drm_priv);
>>   err_free_mem:
>>       kfree(*mem);
>> +    return ret;
>> +}
>> +
>> +int amdgpu_amdkfd_gpuvm_import_dmabuf_fd(struct amdgpu_device *adev, 
>> int fd,
>> +                     uint64_t va, void *drm_priv,
>> +                     struct kgd_mem **mem, uint64_t *size,
>> +                     uint64_t *mmap_offset)
>> +{
>> +    struct drm_gem_object *obj;
>> +    uint32_t handle;
>> +    int ret;
>> +
>> +    ret = drm_gem_prime_fd_to_handle(&adev->ddev, 
>> adev->kfd.client.file, fd,
>> +                     &handle);
>> +    if (ret)
>> +        return ret;
>> +    obj = drm_gem_object_lookup(adev->kfd.client.file, handle);
>> +    if (!obj) {
>> +        ret = -EINVAL;
>> +        goto err_release_handle;
>> +    }
>> +
>> +    ret = import_obj_create(adev, obj->dma_buf, obj, va, drm_priv, 
>> mem, size,
>> +                mmap_offset);
>> +    if (ret)
>> +        goto err_put_obj;
>> +
>> +    (*mem)->gem_handle = handle;
>> +
>> +    return 0;
>> +
>>   err_put_obj:
>>       drm_gem_object_put(obj);
>> +err_release_handle:
>> +    drm_gem_handle_delete(adev->kfd.client.file, handle);
>>       return ret;
>>   }
>>   diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c 
>> b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>> index 4417a9863cd0..1a2e9f564b7f 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
>> @@ -1564,16 +1564,11 @@ static int kfd_ioctl_import_dmabuf(struct 
>> file *filep,
>>   {
>>       struct kfd_ioctl_import_dmabuf_args *args = data;
>>       struct kfd_process_device *pdd;
>> -    struct dma_buf *dmabuf;
>>       int idr_handle;
>>       uint64_t size;
>>       void *mem;
>>       int r;
>>   -    dmabuf = dma_buf_get(args->dmabuf_fd);
>> -    if (IS_ERR(dmabuf))
>> -        return PTR_ERR(dmabuf);
>> -
>>       mutex_lock(&p->mutex);
>>       pdd = kfd_process_device_data_by_id(p, args->gpu_id);
>>       if (!pdd) {
>> @@ -1587,10 +1582,10 @@ static int kfd_ioctl_import_dmabuf(struct 
>> file *filep,
>>           goto err_unlock;
>>       }
>>   -    r = amdgpu_amdkfd_gpuvm_import_dmabuf(pdd->dev->adev, dmabuf,
>> -                          args->va_addr, pdd->drm_priv,
>> -                          (struct kgd_mem **)&mem, &size,
>> -                          NULL);
>> +    r = amdgpu_amdkfd_gpuvm_import_dmabuf_fd(pdd->dev->adev, 
>> args->dmabuf_fd,
>> +                         args->va_addr, pdd->drm_priv,
>> +                         (struct kgd_mem **)&mem, &size,
>> +                         NULL);
>>       if (r)
>>           goto err_unlock;
>>   @@ -1601,7 +1596,6 @@ static int kfd_ioctl_import_dmabuf(struct 
>> file *filep,
>>       }
>>         mutex_unlock(&p->mutex);
>> -    dma_buf_put(dmabuf);
>>         args->handle = MAKE_HANDLE(args->gpu_id, idr_handle);
>>   @@ -1612,7 +1606,6 @@ static int kfd_ioctl_import_dmabuf(struct 
>> file *filep,
>>                              pdd->drm_priv, NULL);
>>   err_unlock:
>>       mutex_unlock(&p->mutex);
>> -    dma_buf_put(dmabuf);
>>       return r;
>>   }