[Xen-devel] [PATCH 3/4] xen/arm: create_p2m_entries should not call free_domheap_page

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

The guest is entitled to use valid memory pages as pfns for grant_table
usage.

In these cases we shouldn't call free_domheap_page to free the existing
page from create_p2m_entries, because it resets the reference counting
but the page is still allocated to the guest (even if not in the p2m
anymore) and common grant_table code is also going to call put_page on
it.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 xen/arch/arm/p2m.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 7c23b7d..7ae4515 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -189,12 +189,7 @@ static int create_p2m_entries(struct domain *d,
         /* else: third already valid */
 
         if ( third[third_table_offset(addr)].p2m.valid )
-        {
-            /* p2m entry already present */
-            free_domheap_page(
-                    mfn_to_page(third[third_table_offset(addr)].p2m.base));
             flush_tlb_all_local();
-        }
 
         /* Allocate a new RAM page and attach */
         switch (op) {
-- 
1.7.2.5


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