drm/gpusvm, drm/pagemap: Move migration functionality to drm_pagemap

The migration functionality and track-keeping of per-pagemap VRAM
mapped to the CPU mm is not per GPU_vm, but rather per pagemap.
This is also reflected by the functions not needing the drm_gpusvm
structures. So move to drm_pagemap.

With this, drm_gpusvm shouldn't really access the page zone-device-data
since its meaning is internal to drm_pagemap. Currently it's used to
reject mapping ranges backed by multiple drm_pagemap allocations.
For now, make the zone-device-data a void pointer.

Alter the interface of drm_gpusvm_migrate_to_devmem() to ensure we don't
pass a gpusvm pointer.

Rename CONFIG_DRM_XE_DEVMEM_MIRROR to CONFIG_DRM_XE_PAGEMAP.

Matt is listed as author of this commit since he wrote most of the code,
and it makes sense to retain his git authorship.
Thomas mostly moved the code around.

v3:
- Kerneldoc fixes (CI)
- Don't update documentation about how the drm_pagemap
  migration should be interpreted until upcoming
  patches where the functionality is implemented.
  (Matt Brost)
v4:
- More kerneldoc fixes around timeslice_ms
  (Himal Ghimiray, Matt Brost)
v6:
- Fix an uninitialized pagemap pointer (CI)

Co-developed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250619134035.170086-2-thomas.hellstrom@linux.intel.com

2 files changed, 101 insertions, 96 deletions

diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
index 6a5156476bf4..4aedc5423aff 100644
--- a/include/drm/drm_gpusvm.h
+++ b/include/drm/drm_gpusvm.h
@@ -16,92 +16,10 @@ struct drm_gpusvm;
 struct drm_gpusvm_notifier;
 struct drm_gpusvm_ops;
 struct drm_gpusvm_range;
-struct drm_gpusvm_devmem;
 struct drm_pagemap;
 struct drm_pagemap_device_addr;
 
 /**
- * struct drm_gpusvm_devmem_ops - Operations structure for GPU SVM device memory
- *
- * This structure defines the operations for GPU Shared Virtual Memory (SVM)
- * device memory. These operations are provided by the GPU driver to manage device memory
- * allocations and perform operations such as migration between device memory and system
- * RAM.
- */
-struct drm_gpusvm_devmem_ops {
-	/**
-	 * @devmem_release: Release device memory allocation (optional)
-	 * @devmem_allocation: device memory allocation
-	 *
-	 * Release device memory allocation and drop a reference to device
-	 * memory allocation.
-	 */
-	void (*devmem_release)(struct drm_gpusvm_devmem *devmem_allocation);
-
-	/**
-	 * @populate_devmem_pfn: Populate device memory PFN (required for migration)
-	 * @devmem_allocation: device memory allocation
-	 * @npages: Number of pages to populate
-	 * @pfn: Array of page frame numbers to populate
-	 *
-	 * Populate device memory page frame numbers (PFN).
-	 *
-	 * Return: 0 on success, a negative error code on failure.
-	 */
-	int (*populate_devmem_pfn)(struct drm_gpusvm_devmem *devmem_allocation,
-				   unsigned long npages, unsigned long *pfn);
-
-	/**
-	 * @copy_to_devmem: Copy to device memory (required for migration)
-	 * @pages: Pointer to array of device memory pages (destination)
-	 * @dma_addr: Pointer to array of DMA addresses (source)
-	 * @npages: Number of pages to copy
-	 *
-	 * Copy pages to device memory.
-	 *
-	 * Return: 0 on success, a negative error code on failure.
-	 */
-	int (*copy_to_devmem)(struct page **pages,
-			      dma_addr_t *dma_addr,
-			      unsigned long npages);
-
-	/**
-	 * @copy_to_ram: Copy to system RAM (required for migration)
-	 * @pages: Pointer to array of device memory pages (source)
-	 * @dma_addr: Pointer to array of DMA addresses (destination)
-	 * @npages: Number of pages to copy
-	 *
-	 * Copy pages to system RAM.
-	 *
-	 * Return: 0 on success, a negative error code on failure.
-	 */
-	int (*copy_to_ram)(struct page **pages,
-			   dma_addr_t *dma_addr,
-			   unsigned long npages);
-};
-
-/**
- * struct drm_gpusvm_devmem - Structure representing a GPU SVM device memory allocation
- *
- * @dev: Pointer to the device structure which device memory allocation belongs to
- * @mm: Pointer to the mm_struct for the address space
- * @detached: device memory allocations is detached from device pages
- * @ops: Pointer to the operations structure for GPU SVM device memory
- * @dpagemap: The struct drm_pagemap of the pages this allocation belongs to.
- * @size: Size of device memory allocation
- * @timeslice_expiration: Timeslice expiration in jiffies
- */
-struct drm_gpusvm_devmem {
-	struct device *dev;
-	struct mm_struct *mm;
-	struct completion detached;
-	const struct drm_gpusvm_devmem_ops *ops;
-	struct drm_pagemap *dpagemap;
-	size_t size;
-	u64 timeslice_expiration;
-};
-
-/**
  * struct drm_gpusvm_ops - Operations structure for GPU SVM
  *
  * This structure defines the operations for GPU Shared Virtual Memory (SVM).
@@ -361,15 +279,6 @@ void drm_gpusvm_range_unmap_pages(struct drm_gpusvm *gpusvm,
 				  struct drm_gpusvm_range *range,
 				  const struct drm_gpusvm_ctx *ctx);
 
-int drm_gpusvm_migrate_to_devmem(struct drm_gpusvm *gpusvm,
-				 struct drm_gpusvm_range *range,
-				 struct drm_gpusvm_devmem *devmem_allocation,
-				 const struct drm_gpusvm_ctx *ctx);
-
-int drm_gpusvm_evict_to_ram(struct drm_gpusvm_devmem *devmem_allocation);
-
-const struct dev_pagemap_ops *drm_gpusvm_pagemap_ops_get(void);
-
 bool drm_gpusvm_has_mapping(struct drm_gpusvm *gpusvm, unsigned long start,
 			    unsigned long end);
 
@@ -380,11 +289,6 @@ drm_gpusvm_range_find(struct drm_gpusvm_notifier *notifier, unsigned long start,
 void drm_gpusvm_range_set_unmapped(struct drm_gpusvm_range *range,
 				   const struct mmu_notifier_range *mmu_range);
 
-void drm_gpusvm_devmem_init(struct drm_gpusvm_devmem *devmem_allocation,
-			    struct device *dev, struct mm_struct *mm,
-			    const struct drm_gpusvm_devmem_ops *ops,
-			    struct drm_pagemap *dpagemap, size_t size);
-
 #ifdef CONFIG_LOCKDEP
 /**
  * drm_gpusvm_driver_set_lock() - Set the lock protecting accesses to GPU SVM
diff --git a/include/drm/drm_pagemap.h b/include/drm/drm_pagemap.h
index 202c157ff4d7..dabc9c365df4 100644
--- a/include/drm/drm_pagemap.h
+++ b/include/drm/drm_pagemap.h
@@ -7,6 +7,7 @@
 #include <linux/types.h>
 
 struct drm_pagemap;
+struct drm_pagemap_zdd;
 struct device;
 
 /**
@@ -104,4 +105,104 @@ struct drm_pagemap {
 	struct device *dev;
 };
 
+struct drm_pagemap_devmem;
+
+/**
+ * struct drm_pagemap_devmem_ops - Operations structure for GPU SVM device memory
+ *
+ * This structure defines the operations for GPU Shared Virtual Memory (SVM)
+ * device memory. These operations are provided by the GPU driver to manage device memory
+ * allocations and perform operations such as migration between device memory and system
+ * RAM.
+ */
+struct drm_pagemap_devmem_ops {
+	/**
+	 * @devmem_release: Release device memory allocation (optional)
+	 * @devmem_allocation: device memory allocation
+	 *
+	 * Release device memory allocation and drop a reference to device
+	 * memory allocation.
+	 */
+	void (*devmem_release)(struct drm_pagemap_devmem *devmem_allocation);
+
+	/**
+	 * @populate_devmem_pfn: Populate device memory PFN (required for migration)
+	 * @devmem_allocation: device memory allocation
+	 * @npages: Number of pages to populate
+	 * @pfn: Array of page frame numbers to populate
+	 *
+	 * Populate device memory page frame numbers (PFN).
+	 *
+	 * Return: 0 on success, a negative error code on failure.
+	 */
+	int (*populate_devmem_pfn)(struct drm_pagemap_devmem *devmem_allocation,
+				   unsigned long npages, unsigned long *pfn);
+
+	/**
+	 * @copy_to_devmem: Copy to device memory (required for migration)
+	 * @pages: Pointer to array of device memory pages (destination)
+	 * @dma_addr: Pointer to array of DMA addresses (source)
+	 * @npages: Number of pages to copy
+	 *
+	 * Copy pages to device memory.
+	 *
+	 * Return: 0 on success, a negative error code on failure.
+	 */
+	int (*copy_to_devmem)(struct page **pages,
+			      dma_addr_t *dma_addr,
+			      unsigned long npages);
+
+	/**
+	 * @copy_to_ram: Copy to system RAM (required for migration)
+	 * @pages: Pointer to array of device memory pages (source)
+	 * @dma_addr: Pointer to array of DMA addresses (destination)
+	 * @npages: Number of pages to copy
+	 *
+	 * Copy pages to system RAM.
+	 *
+	 * Return: 0 on success, a negative error code on failure.
+	 */
+	int (*copy_to_ram)(struct page **pages,
+			   dma_addr_t *dma_addr,
+			   unsigned long npages);
+};
+
+/**
+ * struct drm_pagemap_devmem - Structure representing a GPU SVM device memory allocation
+ *
+ * @dev: Pointer to the device structure which device memory allocation belongs to
+ * @mm: Pointer to the mm_struct for the address space
+ * @detached: device memory allocations is detached from device pages
+ * @ops: Pointer to the operations structure for GPU SVM device memory
+ * @dpagemap: The struct drm_pagemap of the pages this allocation belongs to.
+ * @size: Size of device memory allocation
+ * @timeslice_expiration: Timeslice expiration in jiffies
+ */
+struct drm_pagemap_devmem {
+	struct device *dev;
+	struct mm_struct *mm;
+	struct completion detached;
+	const struct drm_pagemap_devmem_ops *ops;
+	struct drm_pagemap *dpagemap;
+	size_t size;
+	u64 timeslice_expiration;
+};
+
+int drm_pagemap_migrate_to_devmem(struct drm_pagemap_devmem *devmem_allocation,
+				  struct mm_struct *mm,
+				  unsigned long start, unsigned long end,
+				  unsigned long timeslice_ms,
+				  void *pgmap_owner);
+
+int drm_pagemap_evict_to_ram(struct drm_pagemap_devmem *devmem_allocation);
+
+const struct dev_pagemap_ops *drm_pagemap_pagemap_ops_get(void);
+
+struct drm_pagemap *drm_pagemap_page_to_dpagemap(struct page *page);
+
+void drm_pagemap_devmem_init(struct drm_pagemap_devmem *devmem_allocation,
+			     struct device *dev, struct mm_struct *mm,
+			     const struct drm_pagemap_devmem_ops *ops,
+			     struct drm_pagemap *dpagemap, size_t size);
+
 #endif