xen/m2p: use GNTTABOP_unmap_and_replace to reinstate the original mapping
GNTTABOP_unmap_grant_ref unmaps a grant and replaces it with a 0
mapping instead of reinstating the original mapping.
Doing so separately would be racy.
To unmap a grant and reinstate the original mapping atomically we use
GNTTABOP_unmap_and_replace.
GNTTABOP_unmap_and_replace doesn't work with GNTMAP_contains_pte, so
don't use it for kmaps. GNTTABOP_unmap_and_replace zeroes the mapping
passed in new_addr so we have to reinstate it, however that is a
per-cpu mapping only used for balloon scratch pages, so we can be sure that
it's not going to be accessed while the mapping is not valid.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: alex@alex.org.uk
CC: dcrisan@flexiant.com
[v1: Konrad fixed up the conflicts]
Conflicts:
arch/x86/xen/p2m.c
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index eab5427..e41c79c 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -272,19 +272,12 @@
* with find_grant_ptes.
*/
for (i = 0; i < map->count; i++) {
- unsigned level;
unsigned long address = (unsigned long)
pfn_to_kaddr(page_to_pfn(map->pages[i]));
- pte_t *ptep;
- u64 pte_maddr = 0;
BUG_ON(PageHighMem(map->pages[i]));
- ptep = lookup_address(address, &level);
- pte_maddr = arbitrary_virt_to_machine(ptep).maddr;
- gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
- map->flags |
- GNTMAP_host_map |
- GNTMAP_contains_pte,
+ gnttab_set_map_op(&map->kmap_ops[i], address,
+ map->flags | GNTMAP_host_map,
map->grants[i].ref,
map->grants[i].domid);
}