1 files changed, 186 insertions, 0 deletions
diff --git a/drivers/iommu/iommu-pages.h b/drivers/iommu/iommu-pages.h
new file mode 100644
index 000000000000..82ebf0033081
--- /dev/null
+++ b/drivers/iommu/iommu-pages.h
@@ -0,0 +1,186 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2024, Google LLC.
+ * Pasha Tatashin <pasha.tatashin@soleen.com>
+ */
+
+#ifndef __IOMMU_PAGES_H
+#define __IOMMU_PAGES_H
+
+#include <linux/vmstat.h>
+#include <linux/gfp.h>
+#include <linux/mm.h>
+
+/*
+ * All page allocations that should be reported to as "iommu-pagetables" to
+ * userspace must use one of the functions below.  This includes allocations of
+ * page-tables and other per-iommu_domain configuration structures.
+ *
+ * This is necessary for the proper accounting as IOMMU state can be rather
+ * large, i.e. multiple gigabytes in size.
+ */
+
+/**
+ * __iommu_alloc_account - account for newly allocated page.
+ * @page: head struct page of the page.
+ * @order: order of the page
+ */
+static inline void __iommu_alloc_account(struct page *page, int order)
+{
+	const long pgcnt = 1l << order;
+
+	mod_node_page_state(page_pgdat(page), NR_IOMMU_PAGES, pgcnt);
+	mod_lruvec_page_state(page, NR_SECONDARY_PAGETABLE, pgcnt);
+}
+
+/**
+ * __iommu_free_account - account a page that is about to be freed.
+ * @page: head struct page of the page.
+ * @order: order of the page
+ */
+static inline void __iommu_free_account(struct page *page, int order)
+{
+	const long pgcnt = 1l << order;
+
+	mod_node_page_state(page_pgdat(page), NR_IOMMU_PAGES, -pgcnt);
+	mod_lruvec_page_state(page, NR_SECONDARY_PAGETABLE, -pgcnt);
+}
+
+/**
+ * __iommu_alloc_pages - allocate a zeroed page of a given order.
+ * @gfp: buddy allocator flags
+ * @order: page order
+ *
+ * returns the head struct page of the allocated page.
+ */
+static inline struct page *__iommu_alloc_pages(gfp_t gfp, int order)
+{
+	struct page *page;
+
+	page = alloc_pages(gfp | __GFP_ZERO, order);
+	if (unlikely(!page))
+		return NULL;
+
+	__iommu_alloc_account(page, order);
+
+	return page;
+}
+
+/**
+ * __iommu_free_pages - free page of a given order
+ * @page: head struct page of the page
+ * @order: page order
+ */
+static inline void __iommu_free_pages(struct page *page, int order)
+{
+	if (!page)
+		return;
+
+	__iommu_free_account(page, order);
+	__free_pages(page, order);
+}
+
+/**
+ * iommu_alloc_pages_node - allocate a zeroed page of a given order from
+ * specific NUMA node.
+ * @nid: memory NUMA node id
+ * @gfp: buddy allocator flags
+ * @order: page order
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_pages_node(int nid, gfp_t gfp, int order)
+{
+	struct page *page = alloc_pages_node(nid, gfp | __GFP_ZERO, order);
+
+	if (unlikely(!page))
+		return NULL;
+
+	__iommu_alloc_account(page, order);
+
+	return page_address(page);
+}
+
+/**
+ * iommu_alloc_pages - allocate a zeroed page of a given order
+ * @gfp: buddy allocator flags
+ * @order: page order
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_pages(gfp_t gfp, int order)
+{
+	struct page *page = __iommu_alloc_pages(gfp, order);
+
+	if (unlikely(!page))
+		return NULL;
+
+	return page_address(page);
+}
+
+/**
+ * iommu_alloc_page_node - allocate a zeroed page at specific NUMA node.
+ * @nid: memory NUMA node id
+ * @gfp: buddy allocator flags
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_page_node(int nid, gfp_t gfp)
+{
+	return iommu_alloc_pages_node(nid, gfp, 0);
+}
+
+/**
+ * iommu_alloc_page - allocate a zeroed page
+ * @gfp: buddy allocator flags
+ *
+ * returns the virtual address of the allocated page
+ */
+static inline void *iommu_alloc_page(gfp_t gfp)
+{
+	return iommu_alloc_pages(gfp, 0);
+}
+
+/**
+ * iommu_free_pages - free page of a given order
+ * @virt: virtual address of the page to be freed.
+ * @order: page order
+ */
+static inline void iommu_free_pages(void *virt, int order)
+{
+	if (!virt)
+		return;
+
+	__iommu_free_pages(virt_to_page(virt), order);
+}
+
+/**
+ * iommu_free_page - free page
+ * @virt: virtual address of the page to be freed.
+ */
+static inline void iommu_free_page(void *virt)
+{
+	iommu_free_pages(virt, 0);
+}
+
+/**
+ * iommu_put_pages_list - free a list of pages.
+ * @page: the head of the lru list to be freed.
+ *
+ * There are no locking requirement for these pages, as they are going to be
+ * put on a free list as soon as refcount reaches 0. Pages are put on this LRU
+ * list once they are removed from the IOMMU page tables. However, they can
+ * still be access through debugfs.
+ */
+static inline void iommu_put_pages_list(struct list_head *page)
+{
+	while (!list_empty(page)) {
+		struct page *p = list_entry(page->prev, struct page, lru);
+
+		list_del(&p->lru);
+		__iommu_free_account(p, 0);
+		put_page(p);
+	}
+}
+
+#endif	/* __IOMMU_PAGES_H */