[Xen-changelog] [xen master] xen: arm: avoid reusing incorrect mappings when walking the p2m.

[patchbot@xxxxxxx]

commit 964fd5a99c13c707c0c3355743ed1fadf88fc9d9
Author:     Ian Campbell <ian.campbell@xxxxxxxxxx>
AuthorDate: Fri Jul 18 14:33:59 2014 +0100
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Mon Jul 21 12:15:25 2014 +0100

    xen: arm: avoid reusing incorrect mappings when walking the p2m.
    
    When we change which PT page we are mapping at a given level then we need to
    invalidate any cached mappings further down the tree, otherwise we risk 
using
    them because their offset might match but be based on a different offset
    further up the table.
    
    e.g. when remapping first then cur_first_offset and cur_second_offset (which
    indicate the currently mapped second and third tables respectively) both 
become
    invalid
    
    Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>
---
 xen/arch/arm/p2m.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 2f855b5..8ffddac 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -743,6 +743,8 @@ 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_first_offset = cur_second_offset = ~0;
         }
 
         /* We only use a 3 level p2m at the moment, so no level 0,
@@ -765,6 +767,8 @@ 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 */
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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