linux-kernel - [PATCH 3/7] xen/gntdev: Remove apply_to_page

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Message-ID: <20210412080611.702979288@infradead.org>
Date:   Mon, 12 Apr 2021 10:00:15 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        boris.ostrovsky@...cle.com, jgross@...e.com,
        sstabellini@...nel.org, x86@...nel.org,
        jani.nikula@...ux.intel.com, joonas.lahtinen@...ux.intel.com,
        rodrigo.vivi@...el.com, chris@...is-wilson.co.uk,
        intel-gfx@...ts.freedesktop.org, linux-mm@...ck.org,
        keescook@...omium.org, hch@....de
Subject: [PATCH 3/7] xen/gntdev: Remove apply_to_page_range() use from module

Instead of relying on apply_to_page_range() being available to
modules, move its use into core kernel code and export it's
application.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 drivers/xen/gntdev-common.h |    2 ++
 drivers/xen/gntdev.c        |   30 +-----------------------------
 drivers/xen/grant-table.c   |   37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 29 deletions(-)

--- a/drivers/xen/gntdev-common.h
+++ b/drivers/xen/gntdev-common.h
@@ -86,4 +86,6 @@ bool gntdev_test_page_count(unsigned int
 
 int gntdev_map_grant_pages(struct gntdev_grant_map *map);
 
+int gnttab_use_ptemod(struct vm_area_struct *vma, struct gntdev_grant_map *map);
+
 #endif
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -262,32 +262,6 @@ void gntdev_put_map(struct gntdev_priv *
 
 /* ------------------------------------------------------------------ */
 
-static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data)
-{
-	struct gntdev_grant_map *map = data;
-	unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
-	int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
-	u64 pte_maddr;
-
-	BUG_ON(pgnr >= map->count);
-	pte_maddr = arbitrary_virt_to_machine(pte).maddr;
-
-	/*
-	 * Set the PTE as special to force get_user_pages_fast() fall
-	 * back to the slow path.  If this is not supported as part of
-	 * the grant map, it will be done afterwards.
-	 */
-	if (xen_feature(XENFEAT_gnttab_map_avail_bits))
-		flags |= (1 << _GNTMAP_guest_avail0);
-
-	gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
-			  map->grants[pgnr].ref,
-			  map->grants[pgnr].domid);
-	gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
-			    INVALID_GRANT_HANDLE);
-	return 0;
-}
-
 int gntdev_map_grant_pages(struct gntdev_grant_map *map)
 {
 	int i, err = 0;
@@ -1028,9 +1002,7 @@ static int gntdev_mmap(struct file *flip
 		mmu_interval_read_begin(&map->notifier);
 
 		map->pages_vm_start = vma->vm_start;
-		err = apply_to_page_range(vma->vm_mm, vma->vm_start,
-					  vma->vm_end - vma->vm_start,
-					  find_grant_ptes, map);
+		err = gnttab_use_ptemod(vma, map);
 		if (err) {
 			pr_warn("find_grant_ptes() failure.\n");
 			goto out_put_map;
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -1591,6 +1591,43 @@ int gnttab_init(void)
 }
 EXPORT_SYMBOL_GPL(gnttab_init);
 
+#include <xen/gntdev.h>
+#include "gntdev-common.h"
+
+static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data)
+{
+	struct gntdev_grant_map *map = data;
+	unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
+	int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
+	u64 pte_maddr;
+
+	BUG_ON(pgnr >= map->count);
+	pte_maddr = arbitrary_virt_to_machine(pte).maddr;
+
+	/*
+	 * Set the PTE as special to force get_user_pages_fast() fall
+	 * back to the slow path.  If this is not supported as part of
+	 * the grant map, it will be done afterwards.
+	 */
+	if (xen_feature(XENFEAT_gnttab_map_avail_bits))
+		flags |= (1 << _GNTMAP_guest_avail0);
+
+	gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
+			  map->grants[pgnr].ref,
+			  map->grants[pgnr].domid);
+	gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
+			    INVALID_GRANT_HANDLE);
+	return 0;
+}
+
+int gnttab_use_ptemod(struct vm_area_struct *vma, struct gntdev_grant_map *map)
+{
+	return apply_to_page_range(vma->vm_mm, vma->vm_start,
+				   vma->vm_end - vma->vm_start,
+				   find_grant_ptes, map);
+}
+EXPORT_SYMBOL_GPL(gnttab_use_ptemod);
+
 static int __gnttab_init(void)
 {
 	if (!xen_domain())