Sometimes, atomically set spte is not needed, this patch call __xchg_spte()
more smartly
Note: if the old mapping's access bit is already set, we no need atomic operation
since the access bit is not lost
Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index fb3ae54..71e9268 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -682,9 +682,14 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
static void set_spte_track_bits(u64 *sptep, u64 new_spte)
{
pfn_t pfn;
- u64 old_spte;
+ u64 old_spte = *sptep;
+
+ if (!shadow_accessed_mask || !is_shadow_present_pte(old_spte) ||
+ old_spte & shadow_accessed_mask) {
+ __set_spte(sptep, new_spte);
+ } else
+ old_spte = __xchg_spte(sptep, new_spte);
- old_spte = __xchg_spte(sptep, new_spte);
if (!is_rmap_spte(old_spte))
return;
pfn = spte_to_pfn(old_spte);
--
1.6.1.2
--
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