[PATCH v4 5/7] drm/pagemap: Add helper to access zone_device_data

[Francois Dugast <francois.dugast@intel.com>]

This new helper helps ensure all accesses to zone_device_data use the
correct API whether the page is part of a folio or not.

v2:
- Move to drm_pagemap.h, stick to folio_zone_device_data (Matthew Brost)
- Return struct drm_pagemap_zdd * (Matthew Brost)

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: linux-mm@kvack.org
Suggested-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
---
 drivers/gpu/drm/drm_gpusvm.c  |  7 +++++--
 drivers/gpu/drm/drm_pagemap.c | 21 ++++++++++++---------
 include/drm/drm_pagemap.h     | 15 +++++++++++++++
 3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index aa9a0b60e727..585d913d3d19 100644
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c
@@ -1488,12 +1488,15 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm,
 		order = drm_gpusvm_hmm_pfn_to_order(pfns[i], i, npages);
 		if (is_device_private_page(page) ||
 		    is_device_coherent_page(page)) {
+			struct drm_pagemap_zdd *__zdd =
+				drm_pagemap_page_zone_device_data(page);
+
 			if (!ctx->allow_mixed &&
-			    zdd != page->zone_device_data && i > 0) {
+			    zdd != __zdd && i > 0) {
 				err = -EOPNOTSUPP;
 				goto err_unmap;
 			}
-			zdd = page->zone_device_data;
+			zdd = __zdd;
 			if (pagemap != page_pgmap(page)) {
 				if (i > 0) {
 					err = -EOPNOTSUPP;
diff --git a/drivers/gpu/drm/drm_pagemap.c b/drivers/gpu/drm/drm_pagemap.c
index bd9a4703fbce..308c14291eba 100644
--- a/drivers/gpu/drm/drm_pagemap.c
+++ b/drivers/gpu/drm/drm_pagemap.c
@@ -252,7 +252,7 @@ static int drm_pagemap_migrate_map_pages(struct device *dev,
 		order = folio_order(folio);
 
 		if (is_device_private_page(page)) {
-			struct drm_pagemap_zdd *zdd = page->zone_device_data;
+			struct drm_pagemap_zdd *zdd = drm_pagemap_page_zone_device_data(page);
 			struct drm_pagemap *dpagemap = zdd->dpagemap;
 			struct drm_pagemap_addr addr;
 
@@ -323,7 +323,7 @@ static void drm_pagemap_migrate_unmap_pages(struct device *dev,
 			goto next;
 
 		if (is_zone_device_page(page)) {
-			struct drm_pagemap_zdd *zdd = page->zone_device_data;
+			struct drm_pagemap_zdd *zdd = drm_pagemap_page_zone_device_data(page);
 			struct drm_pagemap *dpagemap = zdd->dpagemap;
 
 			dpagemap->ops->device_unmap(dpagemap, dev, pagemap_addr[i]);
@@ -611,7 +611,8 @@ int drm_pagemap_migrate_to_devmem(struct drm_pagemap_devmem *devmem_allocation,
 
 		pages[i] = NULL;
 		if (src_page && is_device_private_page(src_page)) {
-			struct drm_pagemap_zdd *src_zdd = src_page->zone_device_data;
+			struct drm_pagemap_zdd *src_zdd =
+				drm_pagemap_page_zone_device_data(src_page);
 
 			if (page_pgmap(src_page) == pagemap &&
 			    !mdetails->can_migrate_same_pagemap) {
@@ -733,8 +734,8 @@ static int drm_pagemap_migrate_populate_ram_pfn(struct vm_area_struct *vas,
 			goto next;
 
 		if (fault_page) {
-			if (src_page->zone_device_data !=
-			    fault_page->zone_device_data)
+			if (drm_pagemap_page_zone_device_data(src_page) !=
+			    drm_pagemap_page_zone_device_data(fault_page))
 				goto next;
 		}
 
@@ -1075,7 +1076,7 @@ static int __drm_pagemap_migrate_to_ram(struct vm_area_struct *vas,
 	void *buf;
 	int i, err = 0;
 
-	zdd = page->zone_device_data;
+	zdd = drm_pagemap_page_zone_device_data(page);
 	if (time_before64(get_jiffies_64(), zdd->devmem_allocation->timeslice_expiration))
 		return 0;
 
@@ -1159,7 +1160,9 @@ static int __drm_pagemap_migrate_to_ram(struct vm_area_struct *vas,
  */
 static void drm_pagemap_folio_free(struct folio *folio, unsigned int order)
 {
-	drm_pagemap_zdd_put(folio->page.zone_device_data);
+	struct page *page = folio_page(folio, 0);
+
+	drm_pagemap_zdd_put(drm_pagemap_page_zone_device_data(page));
 }
 
 /**
@@ -1175,7 +1178,7 @@ static void drm_pagemap_folio_free(struct folio *folio, unsigned int order)
  */
 static vm_fault_t drm_pagemap_migrate_to_ram(struct vm_fault *vmf)
 {
-	struct drm_pagemap_zdd *zdd = vmf->page->zone_device_data;
+	struct drm_pagemap_zdd *zdd = drm_pagemap_page_zone_device_data(vmf->page);
 	int err;
 
 	err = __drm_pagemap_migrate_to_ram(vmf->vma,
@@ -1241,7 +1244,7 @@ EXPORT_SYMBOL_GPL(drm_pagemap_devmem_init);
  */
 struct drm_pagemap *drm_pagemap_page_to_dpagemap(struct page *page)
 {
-	struct drm_pagemap_zdd *zdd = page->zone_device_data;
+	struct drm_pagemap_zdd *zdd = drm_pagemap_page_zone_device_data(page);
 
 	return zdd->devmem_allocation->dpagemap;
 }
diff --git a/include/drm/drm_pagemap.h b/include/drm/drm_pagemap.h
index 46e9c58f09e0..736fb6cb7b33 100644
--- a/include/drm/drm_pagemap.h
+++ b/include/drm/drm_pagemap.h
@@ -4,6 +4,7 @@
 
 #include <linux/dma-direction.h>
 #include <linux/hmm.h>
+#include <linux/memremap.h>
 #include <linux/types.h>
 
 #define NR_PAGES(order) (1U << (order))
@@ -359,4 +360,18 @@ int drm_pagemap_populate_mm(struct drm_pagemap *dpagemap,
 void drm_pagemap_destroy(struct drm_pagemap *dpagemap, bool is_atomic_or_reclaim);
 
 int drm_pagemap_reinit(struct drm_pagemap *dpagemap);
+
+/**
+ * drm_pagemap_page_zone_device_data() - Page to zone_device_data
+ * @page: Pointer to the page
+ *
+ * Return: Page's zone_device_data
+ */
+static inline struct drm_pagemap_zdd *drm_pagemap_page_zone_device_data(struct page *page)
+{
+	struct folio *folio = page_folio(page);
+
+	return folio_zone_device_data(folio);
+}
+
 #endif
-- 
2.43.0