[PATCH v2 1/1] drm/amdgpu: Add gem_prime_mmap support

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>> +    vma->vm_pgoff = amdgpu_bo_mmap_offset(bo) >> PAGE_SHIFT;
> Maybe better use "vma->vm_pgoff += amdgpu_bo_mmap_offset(bo) >> PAGE_SHIFT;", but I'm not sure.
> How other drivers handle this?
This is a good catch. Looks like pgoff is honored during prime mmap, not a fake offset here.

>> +    dma_buf->ops = &amdgpu_dmabuf_ops;
> This isn't race free and needs to be fixed.
> Better add callbacks to drm_prime.c similar to drm_gem_dmabuf_mmap().
What do you mean "This isn't race free"?

Regards,
Sam



On 2017-09-15 11:05 AM, Christian König wrote:
> Am 14.09.2017 um 00:39 schrieb Samuel Li:
>> v2: drop hdp invalidate/flush.
>>
>> Signed-off-by: Samuel Li <Samuel.Li at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h       |  3 ++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c   |  3 +-
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c | 77 ++++++++++++++++++++++++++++++-
>>   3 files changed, 81 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> index d2aaad7..188b705 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> @@ -395,11 +395,14 @@ amdgpu_gem_prime_import_sg_table(struct drm_device *dev,
>>   struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
>>                       struct drm_gem_object *gobj,
>>                       int flags);
>> +struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev,
>> +                        struct dma_buf *dma_buf);
>>   int amdgpu_gem_prime_pin(struct drm_gem_object *obj);
>>   void amdgpu_gem_prime_unpin(struct drm_gem_object *obj);
>>   struct reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *);
>>   void *amdgpu_gem_prime_vmap(struct drm_gem_object *obj);
>>   void amdgpu_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr);
>> +int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
>>   int amdgpu_gem_debugfs_init(struct amdgpu_device *adev);
>>     /* sub-allocation manager, it has to be protected by another lock.
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> index 2cdf844..9b63ac5 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> @@ -835,7 +835,7 @@ static struct drm_driver kms_driver = {
>>       .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
>>       .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
>>       .gem_prime_export = amdgpu_gem_prime_export,
>> -    .gem_prime_import = drm_gem_prime_import,
>> +    .gem_prime_import = amdgpu_gem_prime_import,
>>       .gem_prime_pin = amdgpu_gem_prime_pin,
>>       .gem_prime_unpin = amdgpu_gem_prime_unpin,
>>       .gem_prime_res_obj = amdgpu_gem_prime_res_obj,
>> @@ -843,6 +843,7 @@ static struct drm_driver kms_driver = {
>>       .gem_prime_import_sg_table = amdgpu_gem_prime_import_sg_table,
>>       .gem_prime_vmap = amdgpu_gem_prime_vmap,
>>       .gem_prime_vunmap = amdgpu_gem_prime_vunmap,
>> +    .gem_prime_mmap = amdgpu_gem_prime_mmap,
>>         .name = DRIVER_NAME,
>>       .desc = DRIVER_DESC,
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
>> index 5b3f928..13c977a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_prime.c
>> @@ -57,6 +57,40 @@ void amdgpu_gem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
>>       ttm_bo_kunmap(&bo->dma_buf_vmap);
>>   }
>>   +int amdgpu_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
>> +{
>> +    struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
>> +    struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
>> +    unsigned asize = amdgpu_bo_size(bo);
>> +    int ret;
>> +
>> +    if (!vma->vm_file)
>> +        return -ENODEV;
>> +
>> +    if (adev == NULL)
>> +        return -ENODEV;
>> +
>> +    /* Check for valid size. */
>> +    if (asize < vma->vm_end - vma->vm_start)
>> +        return -EINVAL;
>> +
>> +    if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm) ||
>> +        (bo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS)) {
>> +        return -EPERM;
>> +    }
>> +    vma->vm_pgoff = amdgpu_bo_mmap_offset(bo) >> PAGE_SHIFT;
> 
> Maybe better use "vma->vm_pgoff += amdgpu_bo_mmap_offset(bo) >> PAGE_SHIFT;", but I'm not sure.
> 
> How other drivers handle this?
> 
>> +
>> +    /* prime mmap does not need to check access, so allow here */
>> +    ret = drm_vma_node_allow(&obj->vma_node, vma->vm_file->private_data);
>> +    if (ret)
>> +        return ret;
>> +
>> +    ret = ttm_bo_mmap(vma->vm_file, vma, &adev->mman.bdev);
>> +    drm_vma_node_revoke(&obj->vma_node, vma->vm_file->private_data);
>> +
>> +    return ret;
>> +}
>> +
>>   struct drm_gem_object *
>>   amdgpu_gem_prime_import_sg_table(struct drm_device *dev,
>>                    struct dma_buf_attachment *attach,
>> @@ -130,14 +164,55 @@ struct reservation_object *amdgpu_gem_prime_res_obj(struct drm_gem_object *obj)
>>       return bo->tbo.resv;
>>   }
>>   +static int amdgpu_gem_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
>> +{
>> +    return amdgpu_gem_prime_pin(dma_buf->priv);
>> +}
>> +
>> +static int amdgpu_gem_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction direction)
>> +{
>> +    amdgpu_gem_prime_unpin(dma_buf->priv);
>> +
>> +    return 0;
>> +}
>> +
>> +static struct dma_buf_ops amdgpu_dmabuf_ops;
>> +
>>   struct dma_buf *amdgpu_gem_prime_export(struct drm_device *dev,
>>                       struct drm_gem_object *gobj,
>>                       int flags)
>>   {
>>       struct amdgpu_bo *bo = gem_to_amdgpu_bo(gobj);
>> +    struct dma_buf *dma_buf;
>>         if (amdgpu_ttm_tt_get_usermm(bo->tbo.ttm))
>>           return ERR_PTR(-EPERM);
>>   -    return drm_gem_prime_export(dev, gobj, flags);
>> +    dma_buf = drm_gem_prime_export(dev, gobj, flags);
>> +    amdgpu_dmabuf_ops = *(dma_buf->ops);
>> +    amdgpu_dmabuf_ops.begin_cpu_access = amdgpu_gem_begin_cpu_access;
>> +    amdgpu_dmabuf_ops.end_cpu_access = amdgpu_gem_end_cpu_access;
>> +    dma_buf->ops = &amdgpu_dmabuf_ops;
> 
> This isn't race free and needs to be fixed.
> 
> Better add callbacks to drm_prime.c similar to drm_gem_dmabuf_mmap().
> 
> Alternative you could just completely drop amdgpu_gem_begin_cpu_access() and amdgpu_gem_end_cpu_access() as well.
> 
> When the buffer is shared between device it is pinned anyway and when it isn't shared ttm_bo_mmap() is able to handle VRAM mappings as well.
> 
> Regards,
> Christian.
> 
>> +
>> +    return dma_buf;
>> +}
>> +
>> +struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev,
>> +                        struct dma_buf *dma_buf)
>> +{
>> +    struct drm_gem_object *obj;
>> +
>> +    if (dma_buf->ops == &amdgpu_dmabuf_ops) {
>> +        obj = dma_buf->priv;
>> +        if (obj->dev == dev) {
>> +            /*
>> +             * Importing dmabuf exported from out own gem increases
>> +             * refcount on gem itself instead of f_count of dmabuf.
>> +             */
>> +            drm_gem_object_get(obj);
>> +            return obj;
>> +        }
>> +    }
>> +
>> +    return drm_gem_prime_import(dev, dma_buf);
>>   }
> 
> 


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