[PATCH 1/2] drm/xe: keep list of system pages in xe_userptr

[Andrzej Hajda <andrzej.hajda@intel.com>]

In case of accessing data provided by userptr in the driver we need to
have list of corresponding pages. This list is created by
xe_hmm_userptr_populate_range and stored in xe_userptr.sgl sg list.
Since we are not allowed to get pages from sg list, let's store them in
separate field.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
---
 drivers/gpu/drm/xe/xe_hmm.c      | 52 ++++++++++++++++----------------
 drivers/gpu/drm/xe/xe_vm_types.h |  2 ++
 2 files changed, 28 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_hmm.c b/drivers/gpu/drm/xe/xe_hmm.c
index 2c32dc46f7d4..6fc21e04ef2e 100644
--- a/drivers/gpu/drm/xe/xe_hmm.c
+++ b/drivers/gpu/drm/xe/xe_hmm.c
@@ -44,13 +44,13 @@ static void xe_mark_range_accessed(struct hmm_range *range, bool write)
 }
 
 /*
- * xe_build_sg() - build a scatter gather table for all the physical pages/pfn
- * in a hmm_range. dma-map pages if necessary. dma-address is save in sg table
+ * xe_build_sg() - build a scatter gather table for given physical pages
+ * and perform dma-map. dma-address is saved in sg table
  * and will be used to program GPU page table later.
  *
  * @xe: the xe device who will access the dma-address in sg table
- * @range: the hmm range that we build the sg table from. range->hmm_pfns[]
- * has the pfn numbers of pages that back up this hmm address range.
+ * @pages: array of page pointers
+ * @npages: number of entries in @pages
  * @st: pointer to the sg table.
  * @write: whether we write to this range. This decides dma map direction
  * for system pages. If write we map it bi-diretional; otherwise
@@ -77,38 +77,22 @@ static void xe_mark_range_accessed(struct hmm_range *range, bool write)
  *
  * Returns 0 if successful; -ENOMEM if fails to allocate memory
  */
-static int xe_build_sg(struct xe_device *xe, struct hmm_range *range,
+static int xe_build_sg(struct xe_device *xe, struct page **pages, u64 npages,
 		       struct sg_table *st, bool write)
 {
 	struct device *dev = xe->drm.dev;
-	struct page **pages;
-	u64 i, npages;
 	int ret;
 
-	npages = xe_npages_in_range(range->start, range->end);
-	pages = kvmalloc_array(npages, sizeof(*pages), GFP_KERNEL);
-	if (!pages)
-		return -ENOMEM;
-
-	for (i = 0; i < npages; i++) {
-		pages[i] = hmm_pfn_to_page(range->hmm_pfns[i]);
-		xe_assert(xe, !is_device_private_page(pages[i]));
-	}
-
 	ret = sg_alloc_table_from_pages_segment(st, pages, npages, 0, npages << PAGE_SHIFT,
 						xe_sg_segment_size(dev), GFP_KERNEL);
 	if (ret)
-		goto free_pages;
+		return ret;
 
 	ret = dma_map_sgtable(dev, st, write ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE,
 			      DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_NO_KERNEL_MAPPING);
-	if (ret) {
+	if (ret)
 		sg_free_table(st);
-		st = NULL;
-	}
 
-free_pages:
-	kvfree(pages);
 	return ret;
 }
 
@@ -136,6 +120,8 @@ void xe_hmm_userptr_free_sg(struct xe_userptr_vma *uvma)
 
 	sg_free_table(userptr->sg);
 	userptr->sg = NULL;
+	kvfree(userptr->pages);
+	userptr->pages = NULL;
 }
 
 /**
@@ -175,7 +161,7 @@ int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma,
 	struct hmm_range hmm_range;
 	bool write = !xe_vma_read_only(vma);
 	unsigned long notifier_seq;
-	u64 npages;
+	u64 i, npages;
 	int ret;
 
 	userptr = &uvma->userptr;
@@ -238,9 +224,23 @@ int xe_hmm_userptr_populate_range(struct xe_userptr_vma *uvma,
 	if (ret)
 		goto free_pfns;
 
-	ret = xe_build_sg(vm->xe, &hmm_range, &userptr->sgt, write);
-	if (ret)
+	userptr->pages = kvmalloc_array(npages, sizeof(*userptr->pages), GFP_KERNEL);
+	if (!userptr->pages) {
+		ret = -ENOMEM;
+		goto free_pfns;
+	}
+
+	for (i = 0; i < npages; i++) {
+		userptr->pages[i] = hmm_pfn_to_page(hmm_range.hmm_pfns[i]);
+		xe_assert(vm->xe, !is_device_private_page(userptr->pages[i]));
+	}
+
+	ret = xe_build_sg(vm->xe, userptr->pages, npages, &userptr->sgt, write);
+	if (ret) {
+		kvfree(userptr->pages);
+		userptr->pages = NULL;
 		goto free_pfns;
+	}
 
 	xe_mark_range_accessed(&hmm_range, write);
 	userptr->sg = &userptr->sgt;
diff --git a/drivers/gpu/drm/xe/xe_vm_types.h b/drivers/gpu/drm/xe/xe_vm_types.h
index 557b047ebdd7..f1ec3925dea0 100644
--- a/drivers/gpu/drm/xe/xe_vm_types.h
+++ b/drivers/gpu/drm/xe/xe_vm_types.h
@@ -53,6 +53,8 @@ struct xe_userptr {
 	 * @notifier: MMU notifier for user pointer (invalidation call back)
 	 */
 	struct mmu_interval_notifier notifier;
+	/** @pages: pointer to array of pointers to corresponding pages */
+	struct page **pages;
 	/** @sgt: storage for a scatter gather table */
 	struct sg_table sgt;
 	/** @sg: allocated scatter gather table */
-- 
2.34.1