x86/mem-sharing: ensure consistent lock order in get_two_gfns()

While the comment validly says "Sort by domain, if same domain by gfn", the implementation also included equal domain IDs in the first part of the check, thus rending the second part entirely dead and leaving deadlock potential when there's only a single domain involved. Signed-off-by: Jan Beulich <[email protected]> Acked-by: Tamas K Lengyel <[email protected]>
nephele-vm · Jul 7, 2021 · 09af2d0 · 09af2d0
1 parent 980d6ac
commit 09af2d0
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
@@ -587,7 +587,7 @@ do {                                                    \
     dest ## _t   = (source ## t)   ?: &scratch_t;       \
 } while (0)
 
-    if ( (rd->domain_id <= ld->domain_id) ||
+    if ( (rd->domain_id < ld->domain_id) ||
          ((rd == ld) && (gfn_x(rgfn) <= gfn_x(lgfn))) )
     {
         assign_pointers(first, r);