On Thu, Apr 24, 2025 at 01:18:33PM +0100, Matthew Auld wrote:
> 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.a...@intel.com>
> Cc: Thomas Hellström <thomas.hellst...@linux.intel.com>
> Cc: Matthew Brost <matthew.br...@intel.com>
> ---
> drivers/gpu/drm/drm_gpusvm.c | 66 ++++++++++++++++++++++++++++--------
> include/drm/drm_gpusvm.h | 16 +++++++++
> 2 files changed, 67 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
> index fbe0d70ef163..0e0a3c995b4b 100644
> --- a/drivers/gpu/drm/drm_gpusvm.c
> +++ b/drivers/gpu/drm/drm_gpusvm.c
> @@ -539,6 +539,12 @@ 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,
> @@ -549,8 +555,16 @@ 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) {
Do you still need this if statement if GPU SVM is shared between userptr
and SVM? Shouldn't we always pass in the MM?
Or is this for the mode where SVM is disabled in Xe and we just use the
get_pages functionality?
Matt
> + 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;
> @@ -563,7 +577,6 @@ 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);
>
> @@ -671,7 +684,8 @@ 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);
> @@ -1185,6 +1199,27 @@ 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
> @@ -1360,13 +1395,12 @@ 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 :
> @@ -1548,6 +1582,7 @@ static int drm_gpusvm_get_pages(struct drm_gpusvm
> *gpusvm,
> goto retry;
> return err;
> }
> +EXPORT_SYMBOL_GPL(drm_gpusvm_get_pages);
>
> /**
> * drm_gpusvm_range_get_pages() - Get pages for a GPU SVM range
> @@ -1583,10 +1618,10 @@ 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);
> @@ -1598,6 +1633,7 @@ 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 1b7ed4f4a8e2..611aaba1ac80 100644
> --- a/include/drm/drm_gpusvm.h
> +++ b/include/drm/drm_gpusvm.h
> @@ -370,6 +370,22 @@ void drm_gpusvm_devmem_init(struct drm_gpusvm_devmem
> *devmem_allocation,
> const struct drm_gpusvm_devmem_ops *ops,
> struct drm_pagemap *dpagemap, size_t size);
>
> +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
> --
> 2.49.0
>
