diff options
| -rw-r--r-- | drivers/xen/gntdev.c | 34 | ||||
| -rw-r--r-- | include/xen/interface/features.h | 6 | ||||
| -rw-r--r-- | include/xen/interface/grant_table.h | 7 |
3 files changed, 47 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; diff --git a/include/xen/interface/features.h b/include/xen/interface/features.h index 131a6cc..6ad3d11 100644 --- a/include/xen/interface/features.h +++ b/include/xen/interface/features.h @@ -41,6 +41,12 @@ /* x86: Does this Xen host support the MMU_PT_UPDATE_PRESERVE_AD hypercall? */ #define XENFEAT_mmu_pt_update_preserve_ad 5 +/* + * If set, GNTTABOP_map_grant_ref honors flags to be placed into guest kernel + * available pte bits. + */ +#define XENFEAT_gnttab_map_avail_bits 7 + /* x86: Does this Xen host support the HVM callback vector type? */ #define XENFEAT_hvm_callback_vector 8 diff --git a/include/xen/interface/grant_table.h b/include/xen/interface/grant_table.h index bcce564..56806bc 100644 --- a/include/xen/interface/grant_table.h +++ b/include/xen/interface/grant_table.h @@ -526,6 +526,13 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush); #define GNTMAP_contains_pte (1<<_GNTMAP_contains_pte) /* + * Bits to be placed in guest kernel available PTE bits (architecture + * dependent; only supported when XENFEAT_gnttab_map_avail_bits is set). + */ +#define _GNTMAP_guest_avail0 (16) +#define GNTMAP_guest_avail_mask ((uint32_t)~0 << _GNTMAP_guest_avail0) + +/* * Values for error status returns. All errors are -ve. */ #define GNTST_okay (0) /* Normal return. */ |