[Xen-devel] [PATCH] x86/mm/shadow: spurious warning when unmapping xenheap pages.

[Tim Deegan <tim@xxxxxxx>]

Xenheap pages will always have an extra typecount, taken in
share_xen_page_with_guest(), which doesn't come from a shadow PTE.
Adjust the warning in sh_remove_all_mappings() to account for it.

Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Signed-off-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm/shadow/common.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 4b576ac..adffa06 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -2437,10 +2437,13 @@ int sh_remove_all_mappings(struct vcpu *v, mfn_t gmfn)
     {
         /* Don't complain if we're in HVM and there are some extra mappings: 
          * The qemu helper process has an untyped mapping of this dom's RAM 
-         * and the HVM restore program takes another. */
+         * and the HVM restore program takes another.
+         * Also allow one typed refcount for xenheap pages, to match
+         * share_xen_page_with_guest(). */
         if ( !(shadow_mode_external(v->domain)
                && (page->count_info & PGC_count_mask) <= 3
-               && (page->u.inuse.type_info & PGT_count_mask) == 0) )
+               && ((page->u.inuse.type_info & PGT_count_mask)
+                   == !!is_xen_heap_page(page))) )
         {
             SHADOW_ERROR("can't find all mappings of mfn %lx: "
                           "c=%08lx t=%08lx\n", mfn_x(gmfn), 
-- 
1.7.10.4


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