KVM: MMU: Move accessed/dirty bit checks from rmap_remove() to drop_spte()

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>

1 files changed, 11 insertions, 8 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1ad39cf70e1..fbdca08b8d8 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);
 }