x86/mm: Enforce ordering constraints for the page alloc lock in the PoD code

The page alloc lock is sometimes used in the PoD code, with an
explicit expectation of ordering. Use our ordering constructs in the
mm layer to enforce this.

The additional book-keeping variables are kept in the arch_domain
sub-struct, as they are x86-specific to the whole domain.

Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org>
Acked-by: Tim Deegan <tim@xen.org>
Committed-by: Tim Deegan <tim@xen.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index 3e4408a0b9..00bbaebfcc 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -269,6 +269,9 @@ struct arch_domain
 
     struct paging_domain paging;
     struct p2m_domain *p2m;
+    /* To enforce lock ordering in the pod code wrt the 
+     * page_alloc lock */
+    int page_alloc_unlock_level;
 
     /* nestedhvm: translate l2 guest physical to host physical */
     struct p2m_domain *nested_p2m[MAX_NESTEDP2M];