[Xen-devel] [PATCH 1/3] xen: arm: avoid reusing incorrect mappings when walking the p2m.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

If we handle a change in a superpage then we need to invalidate any cached
mappings further down, otherwise we risk using them because their offset might
match but be based on a different offset further up the table.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/arch/arm/p2m.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index c0c011a..917baa3 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -719,6 +719,8 @@ static int apply_p2m_changes(struct domain *d,
                 goto out;
             }
             cur_first_page = p2m_first_level_index(addr);
+            /* Any mapping further down is now invalid */
+            cur_second_offset = ~0;
         }
 
         /* We only use a 3 level p2m at the moment, so no level 0,
@@ -741,6 +743,8 @@ static int apply_p2m_changes(struct domain *d,
             if (second) unmap_domain_page(second);
             second = map_domain_page(first[first_table_offset(addr)].p2m.base);
             cur_first_offset = first_table_offset(addr);
+            /* Any mapping further down is now invalid */
+            cur_second_offset = ~0;
         }
         /* else: second already valid */
 
-- 
1.7.10.4


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