[PATCH] kvm, mmu: fix incorrect return of spte

From: Zhao Jin
Date: Mon Sep 19 2011 - 00:20:10 EST


__update_clear_spte_slow should return original spte while the
current code returns low half of original spte combined with high
half of new spte.

Signed-off-by: Zhao Jin <cronozhj@xxxxxxxxx>
---
arch/x86/kvm/mmu.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1c5b693..8e8da79 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -400,7 +400,8 @@ static u64 __update_clear_spte_slow(u64 *sptep, u64 spte)

/* xchg acts as a barrier before the setting of the high bits */
orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low);
- orig.spte_high = ssptep->spte_high = sspte.spte_high;
+ orig.spte_high = ssptep->spte_high;
+ ssptep->spte_high = sspte.spte_high;
count_spte_clear(sptep, spte);

return orig.spte;
--
1.7.4.1

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