[PATCH 5.5 220/367] xen/gntdev: Do not use mm notifiers with autotranslating guests

Greg Kroah-Hartman
2020-02-10T13:00:15Z

From: Boris Ostrovsky <boris.ostrovsky@oracle.com>

commit 9293724192a73f49c722e9685d45649c6df67dfe upstream.

Commit d3eeb1d77c5d ("xen/gntdev: use mmu_interval_notifier_insert")
missed a test for use_ptemod when calling mmu_interval_read_begin(). Fix
that.

Fixes: d3eeb1d77c5d ("xen/gntdev: use mmu_interval_notifier_insert")
CC: stable@vger.kernel.org # 5.5
Reported-by: Ilpo Järvinen <ilpo.jarvinen@cs.helsinki.fi>
Tested-by: Ilpo Järvinen <ilpo.jarvinen@cs.helsinki.fi>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/xen/gntdev.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1006,19 +1006,19 @@ static int gntdev_mmap(struct file *flip
}
mutex_unlock(&priv->lock);

- /*
- * gntdev takes the address of the PTE in find_grant_ptes() and passes
- * it to the hypervisor in gntdev_map_grant_pages(). The purpose of
- * the notifier is to prevent the hypervisor pointer to the PTE from
- * going stale.
- *
- * Since this vma's mappings can't be touched without the mmap_sem,
- * and we are holding it now, there is no need for the notifier_range
- * locking pattern.
- */
- mmu_interval_read_begin(&map->notifier);
-
if (use_ptemod) {
+ /*
+ * gntdev takes the address of the PTE in find_grant_ptes() and
+ * passes it to the hypervisor in gntdev_map_grant_pages(). The
+ * purpose of the notifier is to prevent the hypervisor pointer
+ * to the PTE from going stale.
+ *
+ * Since this vma's mappings can't be touched without the
+ * mmap_sem, and we are holding it now, there is no need for
+ * the notifier_range locking pattern.
+ */
+ 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,