[PATCH v2 2/4] KVM: MMU: Move accessed/dirty bit checks from rmap_remove() to drop_spte()

Avi Kivity
2010-06-07T07:11:01Z

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 | 17 +++++++++--------
1 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 16cedc9..b5a2d3d 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -620,19 +620,11 @@ 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) {
@@ -668,6 +660,15 @@ 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))
+ 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