Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 81401f3..e953ea3 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -319,44 +319,47 @@
 		 * to the kernel linear addresses of the struct pages.
 		 * These ptes are completely different from the user ptes dealt
 		 * with find_grant_ptes.
+		 * Note that GNTMAP_device_map isn't needed here: The
+		 * dev_bus_addr output field gets consumed only from ->map_ops,
+		 * and by not requesting it when mapping we also avoid needing
+		 * to mirror dev_bus_addr into ->unmap_ops (and holding an extra
+		 * reference to the page in the hypervisor).
 		 */
+		unsigned int flags = (map->flags & ~GNTMAP_device_map) |
+				     GNTMAP_host_map;
+
 		for (i = 0; i < map->count; i++) {
 			unsigned long address = (unsigned long)
 				pfn_to_kaddr(page_to_pfn(map->pages[i]));
 			BUG_ON(PageHighMem(map->pages[i]));
 
-			gnttab_set_map_op(&map->kmap_ops[i], address,
-				map->flags | GNTMAP_host_map,
+			gnttab_set_map_op(&map->kmap_ops[i], address, flags,
 				map->grants[i].ref,
 				map->grants[i].domid);
 			gnttab_set_unmap_op(&map->kunmap_ops[i], address,
-				map->flags | GNTMAP_host_map, -1);
+				flags, -1);
 		}
 	}
 
 	pr_debug("map %d+%d\n", map->index, map->count);
 	err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 			map->pages, map->count);
-	if (err)
-		return err;
 
 	for (i = 0; i < map->count; i++) {
-		if (map->map_ops[i].status) {
+		if (map->map_ops[i].status == GNTST_okay)
+			map->unmap_ops[i].handle = map->map_ops[i].handle;
+		else if (!err)
 			err = -EINVAL;
-			continue;
-		}
 
-		map->unmap_ops[i].handle = map->map_ops[i].handle;
-		if (use_ptemod)
-			map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
-#ifdef CONFIG_XEN_GRANT_DMA_ALLOC
-		else if (map->dma_vaddr) {
-			unsigned long bfn;
+		if (map->flags & GNTMAP_device_map)
+			map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr;
 
-			bfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
-			map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn);
+		if (use_ptemod) {
+			if (map->kmap_ops[i].status == GNTST_okay)
+				map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
+			else if (!err)
+				err = -EINVAL;
 		}
-#endif
 	}
 	return err;
 }
@@ -831,17 +834,18 @@
 	s16 __user *status[GNTDEV_COPY_BATCH];
 	unsigned int nr_ops;
 	unsigned int nr_pages;
+	bool writeable;
 };
 
 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
-			   bool writeable, unsigned long *gfn)
+				unsigned long *gfn)
 {
 	unsigned long addr = (unsigned long)virt;
 	struct page *page;
 	unsigned long xen_pfn;
 	int ret;
 
-	ret = get_user_pages_fast(addr, 1, writeable ? FOLL_WRITE : 0, &page);
+	ret = get_user_pages_fast(addr, 1, batch->writeable ? FOLL_WRITE : 0, &page);
 	if (ret < 0)
 		return ret;
 
@@ -857,9 +861,13 @@
 {
 	unsigned int i;
 
-	for (i = 0; i < batch->nr_pages; i++)
+	for (i = 0; i < batch->nr_pages; i++) {
+		if (batch->writeable && !PageDirty(batch->pages[i]))
+			set_page_dirty_lock(batch->pages[i]);
 		put_page(batch->pages[i]);
+	}
 	batch->nr_pages = 0;
+	batch->writeable = false;
 }
 
 static int gntdev_copy(struct gntdev_copy_batch *batch)
@@ -948,8 +956,9 @@
 			virt = seg->source.virt + copied;
 			off = (unsigned long)virt & ~XEN_PAGE_MASK;
 			len = min(len, (size_t)XEN_PAGE_SIZE - off);
+			batch->writeable = false;
 
-			ret = gntdev_get_page(batch, virt, false, &gfn);
+			ret = gntdev_get_page(batch, virt, &gfn);
 			if (ret < 0)
 				return ret;
 
@@ -967,8 +976,9 @@
 			virt = seg->dest.virt + copied;
 			off = (unsigned long)virt & ~XEN_PAGE_MASK;
 			len = min(len, (size_t)XEN_PAGE_SIZE - off);
+			batch->writeable = true;
 
-			ret = gntdev_get_page(batch, virt, true, &gfn);
+			ret = gntdev_get_page(batch, virt, &gfn);
 			if (ret < 0)
 				return ret;