[PATCH v2 1/7] KVM: MMU: correct the behavior of mmu_spte_update_no_track

From: guangrong . xiao
Date: Tue Jun 20 2017 - 05:18:24 EST


From: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxx>

Current behavior of mmu_spte_update_no_track() does not match
the name of _no_track() as actually the A/D bits are tracked
and returned to the caller

This patch introduces the real _no_track() function to update
the spte regardless of A/D bits and rename the original function
to _track()

The _no_track() function will be used by later patches to update
upper spte which need not care of A/D bits indeed

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5d3376f..d18c17c 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -583,10 +583,29 @@ static void mmu_spte_set(u64 *sptep, u64 new_spte)
}

/*
- * Update the SPTE (excluding the PFN), but do not track changes in its
+ * Update the SPTE (excluding the PFN) regardless of accessed/dirty
+ * status which is used to update the upper level spte.
+ */
+static void mmu_spte_update_no_track(u64 *sptep, u64 new_spte)
+{
+ u64 old_spte = *sptep;
+
+ WARN_ON(!is_shadow_present_pte(new_spte));
+
+ if (!is_shadow_present_pte(old_spte)) {
+ mmu_spte_set(sptep, new_spte);
+ return;
+ }
+
+ __update_clear_spte_fast(sptep, new_spte);
+}
+
+/*
+ * Update the SPTE (excluding the PFN), the original value is
+ * returned, based on it, the caller can track changes of its
* accessed/dirty status.
*/
-static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte)
+static u64 mmu_spte_update_track(u64 *sptep, u64 new_spte)
{
u64 old_spte = *sptep;

@@ -621,7 +640,7 @@ static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte)
static bool mmu_spte_update(u64 *sptep, u64 new_spte)
{
bool flush = false;
- u64 old_spte = mmu_spte_update_no_track(sptep, new_spte);
+ u64 old_spte = mmu_spte_update_track(sptep, new_spte);

if (!is_shadow_present_pte(old_spte))
return false;
--
2.9.4