[PATCH v3 2/4] KVM: MMU: Move accessed/dirty bit checks from rmap_remove() to drop_spte()

[Avi Kivity <avi@redhat.com>]

Since we need to make the check atomic, move it to the place that will
set the new spte.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 arch/x86/kvm/mmu.c |   19 +++++++++++--------
 1 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5b211dc..e1e6967 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -612,19 +612,11 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
 	struct kvm_rmap_desc *desc;
 	struct kvm_rmap_desc *prev_desc;
 	struct kvm_mmu_page *sp;
-	pfn_t pfn;
 	gfn_t gfn;
 	unsigned long *rmapp;
 	int i;
 
-	if (!is_rmap_spte(*spte))
-		return;
 	sp = page_header(__pa(spte));
-	pfn = spte_to_pfn(*spte);
-	if (*spte & shadow_accessed_mask)
-		kvm_set_pfn_accessed(pfn);
-	if (is_writable_pte(*spte))
-		kvm_set_pfn_dirty(pfn);
 	gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt);
 	rmapp = gfn_to_rmap(kvm, gfn, sp->role.level);
 	if (!*rmapp) {
@@ -660,6 +652,17 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
 
 static void drop_spte(struct kvm *kvm, u64 *sptep, u64 new_spte)
 {
+	pfn_t pfn;
+
+	if (!is_rmap_spte(*sptep)) {
+		__set_spte(sptep, new_spte);
+		return;
+	}
+	pfn = spte_to_pfn(*sptep);
+	if (*sptep & shadow_accessed_mask)
+		kvm_set_pfn_accessed(pfn);
+	if (is_writable_pte(*sptep))
+		kvm_set_pfn_dirty(pfn);
 	rmap_remove(kvm, sptep);
 	__set_spte(sptep, new_spte);
 }
-- 
1.7.1