Re: [RFC 5/5] drm/gpusvm: let the drm_gpusvm core context purely MM level

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Jun 03, 2026 at 02:56:20PM +0800, Honglei Huang wrote:
> From: Honglei Huang <honghuan@amd.com>
> 
> The core mechanism of drm_gpusvm is HMM, which is fundamentally an
> MM side subsystem. A drm_device, enters the picture on the device side at
> DMA mapping / GPU bind.
> 
> So drop struct drm_device from struct drm_gpusvm. Let drm_gpusvm keep
> its core neutral and leave device side decisions to the driver.
> Make drm_gpusvm a pure MM level object.
> 
>   - Drop the drm  from struct drm_gpusvm
>   - Drop the drm parameter from drm_gpusvm_init()
>   - Update the xe call sites in xe_svm_init() and other callers.
> 

I'd mention somewhere that drm_device is now stored in the pages.

Otherwise LGTM.

Matt

> Suggested-by: Matthew Brost <matthew.brost@intel.com>
> Signed-off-by: Honglei Huang <honghuan@amd.com>
> ---
>  drivers/gpu/drm/drm_gpusvm.c | 7 +++----
>  drivers/gpu/drm/xe/xe_svm.c  | 4 ++--
>  drivers/gpu/drm/xe/xe_svm.h  | 2 +-
>  include/drm/drm_gpusvm.h     | 4 +---
>  4 files changed, 7 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
> index 55515390c53..5cade46234c 100644
> --- a/drivers/gpu/drm/drm_gpusvm.c
> +++ b/drivers/gpu/drm/drm_gpusvm.c
> @@ -359,7 +359,6 @@ static const struct mmu_interval_notifier_ops drm_gpusvm_notifier_ops = {
>   * drm_gpusvm_init() - Initialize the GPU SVM.
>   * @gpusvm: Pointer to the GPU SVM structure.
>   * @name: Name of the GPU SVM.
> - * @drm: Pointer to the DRM device structure.
>   * @mm: Pointer to the mm_struct for the address space.
>   * @mm_start: Start address of GPU SVM.
>   * @mm_range: Range of the GPU SVM.
> @@ -373,7 +372,8 @@ static const struct mmu_interval_notifier_ops drm_gpusvm_notifier_ops = {
>   * This function initializes the GPU SVM.
>   *
>   * Note: If only using the simple drm_gpusvm_pages API (get/unmap/free),
> - * then only @gpusvm, @name, and @drm are expected. However, the same base
> + * then only @gpusvm and @name are expected. The struct @drm for dma
> + * mappings is now required in drm_gpusvm_get_pages(). However, the same base
>   * @gpusvm can also be used with both modes together in which case the full
>   * setup is needed, where the core drm_gpusvm_pages API will simply never use
>   * the other fields.
> @@ -381,7 +381,7 @@ static const struct mmu_interval_notifier_ops drm_gpusvm_notifier_ops = {
>   * Return: 0 on success, a negative error code on failure.
>   */
>  int drm_gpusvm_init(struct drm_gpusvm *gpusvm,
> -		    const char *name, struct drm_device *drm,
> +		    const char *name,
>  		    struct mm_struct *mm,
>  		    unsigned long mm_start, unsigned long mm_range,
>  		    unsigned long notifier_size,
> @@ -399,7 +399,6 @@ int drm_gpusvm_init(struct drm_gpusvm *gpusvm,
>  	}
>  
>  	gpusvm->name = name;
> -	gpusvm->drm = drm;
>  	gpusvm->mm = mm;
>  	gpusvm->mm_start = mm_start;
>  	gpusvm->mm_range = mm_range;
> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index 33c26df5111..b0b737234ee 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -905,7 +905,7 @@ int xe_svm_init(struct xe_vm *vm)
>  			return err;
>  		}
>  
> -		err = drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM", &vm->xe->drm,
> +		err = drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM",
>  				      current->mm, 0, vm->size,
>  				      xe_modparam.svm_notifier_size * SZ_1M,
>  				      &gpusvm_ops, fault_chunk_sizes,
> @@ -919,7 +919,7 @@ int xe_svm_init(struct xe_vm *vm)
>  		}
>  	} else {
>  		err = drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM (simple)",
> -				      &vm->xe->drm, NULL, 0, 0, 0, NULL,
> +				      NULL, 0, 0, 0, NULL,
>  				      NULL, 0);
>  	}
>  
> diff --git a/drivers/gpu/drm/xe/xe_svm.h b/drivers/gpu/drm/xe/xe_svm.h
> index ea73241d3d9..1c5195f5495 100644
> --- a/drivers/gpu/drm/xe/xe_svm.h
> +++ b/drivers/gpu/drm/xe/xe_svm.h
> @@ -238,7 +238,7 @@ static inline
>  int xe_svm_init(struct xe_vm *vm)
>  {
>  #if IS_ENABLED(CONFIG_DRM_GPUSVM)
> -	return drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM (simple)", &vm->xe->drm,
> +	return drm_gpusvm_init(&vm->svm.gpusvm, "Xe SVM (simple)",
>  			       NULL, 0, 0, 0, NULL, NULL, 0);
>  #else
>  	return 0;
> diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
> index 250c59f0930..2bea47ee171 100644
> --- a/include/drm/drm_gpusvm.h
> +++ b/include/drm/drm_gpusvm.h
> @@ -191,7 +191,6 @@ struct drm_gpusvm_range {
>   * struct drm_gpusvm - GPU SVM structure
>   *
>   * @name: Name of the GPU SVM
> - * @drm: Pointer to the DRM device structure
>   * @mm: Pointer to the mm_struct for the address space
>   * @mm_start: Start address of GPU SVM
>   * @mm_range: Range of the GPU SVM
> @@ -215,7 +214,6 @@ struct drm_gpusvm_range {
>   */
>  struct drm_gpusvm {
>  	const char *name;
> -	struct drm_device *drm;
>  	struct mm_struct *mm;
>  	unsigned long mm_start;
>  	unsigned long mm_range;
> @@ -267,7 +265,7 @@ struct drm_gpusvm_ctx {
>  };
>  
>  int drm_gpusvm_init(struct drm_gpusvm *gpusvm,
> -		    const char *name, struct drm_device *drm,
> +		    const char *name,
>  		    struct mm_struct *mm,
>  		    unsigned long mm_start, unsigned long mm_range,
>  		    unsigned long notifier_size,
> -- 
> 2.34.1
>