drm/gpusvm: export drm_gpusvm_pages API

Export get/unmap/free pages API. We also need to tweak the SVM init to
allow skipping much of the unneeded parts.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://lore.kernel.org/r/20250828142430.615826-15-matthew.auld@intel.com

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index eb50ed0d0f55abd0deac85565a56f4fa47a2c5f8..eeeeb99cfdf667889991d8e4749d91cc396a103b 100644 (file)
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c
@@ -373,6 +373,12 @@ 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
+ * @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.
+ *
  * Return: 0 on success, a negative error code on failure.
  */
 int drm_gpusvm_init(struct drm_gpusvm *gpusvm,
@@ -383,8 +389,16 @@ int drm_gpusvm_init(struct drm_gpusvm *gpusvm,
                    const struct drm_gpusvm_ops *ops,
                    const unsigned long *chunk_sizes, int num_chunks)
 {
-       if (!ops->invalidate || !num_chunks)
-               return -EINVAL;
+       if (mm) {
+               if (!ops->invalidate || !num_chunks)
+                       return -EINVAL;
+               mmgrab(mm);
+       } else {
+               /* No full SVM mode, only core drm_gpusvm_pages API. */
+               if (ops || num_chunks || mm_range || notifier_size ||
+                   device_private_page_owner)
+                       return -EINVAL;
+       }
 
        gpusvm->name = name;
        gpusvm->drm = drm;
@@ -397,7 +411,6 @@ int drm_gpusvm_init(struct drm_gpusvm *gpusvm,
        gpusvm->chunk_sizes = chunk_sizes;
        gpusvm->num_chunks = num_chunks;
 
-       mmgrab(mm);
        gpusvm->root = RB_ROOT_CACHED;
        INIT_LIST_HEAD(&gpusvm->notifier_list);
 
@@ -489,7 +502,8 @@ void drm_gpusvm_fini(struct drm_gpusvm *gpusvm)
                        drm_gpusvm_range_remove(gpusvm, range);
        }
 
-       mmdrop(gpusvm->mm);
+       if (gpusvm->mm)
+               mmdrop(gpusvm->mm);
        WARN_ON(!RB_EMPTY_ROOT(&gpusvm->root.rb_root));
 }
 EXPORT_SYMBOL_GPL(drm_gpusvm_fini);
@@ -1044,6 +1058,27 @@ static void __drm_gpusvm_free_pages(struct drm_gpusvm *gpusvm,
        }
 }
 
+/**
+ * drm_gpusvm_free_pages() - Free dma-mapping associated with GPU SVM pages
+ * struct
+ * @gpusvm: Pointer to the GPU SVM structure
+ * @svm_pages: Pointer to the GPU SVM pages structure
+ * @npages: Number of mapped pages
+ *
+ * This function unmaps and frees the dma address array associated with a GPU
+ * SVM pages struct.
+ */
+void drm_gpusvm_free_pages(struct drm_gpusvm *gpusvm,
+                          struct drm_gpusvm_pages *svm_pages,
+                          unsigned long npages)
+{
+       drm_gpusvm_notifier_lock(gpusvm);
+       __drm_gpusvm_unmap_pages(gpusvm, svm_pages, npages);
+       __drm_gpusvm_free_pages(gpusvm, svm_pages);
+       drm_gpusvm_notifier_unlock(gpusvm);
+}
+EXPORT_SYMBOL_GPL(drm_gpusvm_free_pages);
+
 /**
  * drm_gpusvm_range_remove() - Remove GPU SVM range
  * @gpusvm: Pointer to the GPU SVM structure
@@ -1220,13 +1255,12 @@ static bool drm_gpusvm_pages_valid_unlocked(struct drm_gpusvm *gpusvm,
  *
  * Return: 0 on success, negative error code on failure.
  */
-static int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
-                               struct drm_gpusvm_pages *svm_pages,
-                               struct mm_struct *mm,
-                               struct mmu_interval_notifier *notifier,
-                               unsigned long pages_start,
-                               unsigned long pages_end,
-                               const struct drm_gpusvm_ctx *ctx)
+int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
+                        struct drm_gpusvm_pages *svm_pages,
+                        struct mm_struct *mm,
+                        struct mmu_interval_notifier *notifier,
+                        unsigned long pages_start, unsigned long pages_end,
+                        const struct drm_gpusvm_ctx *ctx)
 {
        struct hmm_range hmm_range = {
                .default_flags = HMM_PFN_REQ_FAULT | (ctx->read_only ? 0 :
@@ -1415,6 +1449,7 @@ err_free:
                goto retry;
        return err;
 }
+EXPORT_SYMBOL_GPL(drm_gpusvm_get_pages);
 
 /**
  * drm_gpusvm_range_get_pages() - Get pages for a GPU SVM range
@@ -1451,10 +1486,10 @@ EXPORT_SYMBOL_GPL(drm_gpusvm_range_get_pages);
  * Must be called in the invalidate() callback of the corresponding notifier for
  * IOMMU security model.
  */
-static void drm_gpusvm_unmap_pages(struct drm_gpusvm *gpusvm,
-                                  struct drm_gpusvm_pages *svm_pages,
-                                  unsigned long npages,
-                                  const struct drm_gpusvm_ctx *ctx)
+void drm_gpusvm_unmap_pages(struct drm_gpusvm *gpusvm,
+                           struct drm_gpusvm_pages *svm_pages,
+                           unsigned long npages,
+                           const struct drm_gpusvm_ctx *ctx)
 {
        if (ctx->in_notifier)
                lockdep_assert_held_write(&gpusvm->notifier_lock);
@@ -1466,6 +1501,7 @@ static void drm_gpusvm_unmap_pages(struct drm_gpusvm *gpusvm,
        if (!ctx->in_notifier)
                drm_gpusvm_notifier_unlock(gpusvm);
 }
+EXPORT_SYMBOL_GPL(drm_gpusvm_unmap_pages);
 
 /**
  * drm_gpusvm_range_unmap_pages() - Unmap pages associated with a GPU SVM range

diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h
index 1ee4188c30670e9240db11616ffa9cab771e4df6..5434048a2ca45343ea0a2210ae6e4a43f403d419 100644 (file)
--- a/include/drm/drm_gpusvm.h
+++ b/include/drm/drm_gpusvm.h
@@ -307,6 +307,22 @@ 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);
 
+int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
+                        struct drm_gpusvm_pages *svm_pages,
+                        struct mm_struct *mm,
+                        struct mmu_interval_notifier *notifier,
+                        unsigned long pages_start, unsigned long pages_end,
+                        const struct drm_gpusvm_ctx *ctx);
+
+void drm_gpusvm_unmap_pages(struct drm_gpusvm *gpusvm,
+                           struct drm_gpusvm_pages *svm_pages,
+                           unsigned long npages,
+                           const struct drm_gpusvm_ctx *ctx);
+
+void drm_gpusvm_free_pages(struct drm_gpusvm *gpusvm,
+                          struct drm_gpusvm_pages *svm_pages,
+                          unsigned long npages);
+
 #ifdef CONFIG_LOCKDEP
 /**
  * drm_gpusvm_driver_set_lock() - Set the lock protecting accesses to GPU SVM