[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2] 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> --- v2: Also invalidate cur_first_offset when changing cur_first_page. Corrected/clarified commit message, this issue isn't really specific to superpages, they just happen to expose it. --- 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 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 */ -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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