drm/gpusvm: embed struct drm_device into drm_gpusvm_pages

drm_gpusvm_pages is the layer that actually represents physical
pages/mappings it owns the dma_addr array, the dma_iova_state...
With the previous patch, so drm_gpusvm_pages is now strictly about
physical pages and their DMA view.

Since now the drm_gpusvm_pages instance is inherently bound to one
specific drm_device, make that ownership explicit by giving
drm_gpusvm_pages its own drm_device handle, and drive all DMA through
it instead of through the gpusvm:

  - Add drm to struct drm_gpusvm_pages and route all DMA in
    drm_gpusvm_get_pages() / __drm_gpusvm_unmap_pages() through
    svm_pages->drm instead of gpusvm->drm.
  - Bind svm_pages->drm where the pages object is initialised
    (drm_gpusvm_range_alloc() and the xe userptr setup) and require
    it to be set on entry to drm_gpusvm_get_pages(); the dma device
    is immutable for the lifetime of the pages instance. A later
    patch introduces drm_gpusvm_init_pages() to centralise this.

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Honglei Huang <honghuan@amd.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260630102127.392396-3-honghuan@amd.com

1 files changed, 2 insertions, 0 deletions

diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
index 251a7266a73f..842353afb27b 100644
--- a/include/drm/drm_gpusvm.h
+++ b/include/drm/drm_gpusvm.h
@@ -129,6 +129,7 @@ struct drm_gpusvm_pages_flags {
 /**
  * struct drm_gpusvm_pages - Structure representing a GPU SVM mapped pages
  *
+ * @drm: The DRM device that owns the dma mappings
  * @dma_addr: Device address array
  * @dpagemap: The struct drm_pagemap of the device pages we're dma-mapping.
  *            Note this is assuming only one drm_pagemap per range is allowed.
@@ -138,6 +139,7 @@ struct drm_gpusvm_pages_flags {
  * @flags: Flags for the range; see &struct drm_gpusvm_pages_flags
  */
 struct drm_gpusvm_pages {
+	struct drm_device *drm;
 	struct drm_pagemap_addr *dma_addr;
 	struct drm_pagemap *dpagemap;
 	struct dma_iova_state state;