diff options
Diffstat (limited to 'drivers/xen/gntdev.c')
| -rw-r--r-- | drivers/xen/gntdev.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index bccc54a..20c6577 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -244,6 +244,14 @@ static int find_grant_ptes(pte_t *pte, pgtable_t token, 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); @@ -252,6 +260,15 @@ static int find_grant_ptes(pte_t *pte, pgtable_t token, return 0; } +#ifdef CONFIG_X86 +static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token, + unsigned long addr, void *data) +{ + set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte)); + return 0; +} +#endif + static int map_grant_pages(struct grant_map *map) { int i, err = 0; @@ -840,6 +857,23 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) if (err) goto out_put_map; } + } else { +#ifdef CONFIG_X86 + /* + * If the PTEs were not made special by the grant map + * hypercall, do so here. + * + * This is racy since the mapping is already visible + * to userspace but userspace should be well-behaved + * enough to not touch it until the mmap() call + * returns. + */ + if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) { + apply_to_page_range(vma->vm_mm, vma->vm_start, + vma->vm_end - vma->vm_start, + set_grant_ptes_as_special, NULL); + } +#endif } return 0; |