[PATCH 4/4] KVM: MMU: skip obsolete sp in for_each_gfn_*()

[Xiao Guangrong]

The obsolete sp should not be used on current vCPUs and should not hurt
vCPU's running, so skip it from for_each_gfn_sp() and
for_each_gfn_indirect_valid_sp()

The side effort is we will double check role.invalid in kvm_mmu_get_page()
but i think it is okay as role is well cached

Signed-off-by: Xiao Guangrong <guangrong.x...@linux.intel.com>
---
 arch/x86/kvm/mmu.c | 28 ++++++++++++----------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index c396e8b..4d66a9e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1906,18 +1906,17 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
  * since it has been deleted from active_mmu_pages but still can be found
  * at hast list.
  *
- * for_each_gfn_indirect_valid_sp has skipped that kind of page and
- * kvm_mmu_get_page(), the only user of for_each_gfn_sp(), has skipped
- * all the obsolete pages.
+ * for_each_gfn_valid_sp() has skipped that kind of pages.
  */
-#define for_each_gfn_sp(_kvm, _sp, _gfn)                               \
+#define for_each_gfn_valid_sp(_kvm, _sp, _gfn)                         \
        hlist_for_each_entry(_sp,                                       \
          &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
-               if ((_sp)->gfn != (_gfn)) {} else
+               if ((_sp)->gfn != (_gfn) || is_obsolete_sp((_kvm), (_sp)) \
+                       || (_sp)->role.invalid) {} else
 
 #define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn)                        
\
-       for_each_gfn_sp(_kvm, _sp, _gfn)                                \
-               if ((_sp)->role.direct || (_sp)->role.invalid) {} else
+       for_each_gfn_valid_sp(_kvm, _sp, _gfn)                          \
+               if ((_sp)->role.direct) {} else
 
 /* @sp->gfn should be write-protected at the call site */
 static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
@@ -1958,6 +1957,11 @@ static void kvm_mmu_audit(struct kvm_vcpu *vcpu, int 
point) { }
 static void mmu_audit_disable(void) { }
 #endif
 
+static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+       return unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen);
+}
+
 static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
                         struct list_head *invalid_list)
 {
@@ -2092,11 +2096,6 @@ static void clear_sp_write_flooding_count(u64 *spte)
        __clear_sp_write_flooding_count(sp);
 }
 
-static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp)
-{
-       return unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen);
-}
-
 static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
                                             gfn_t gfn,
                                             gva_t gaddr,
@@ -2123,10 +2122,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct 
kvm_vcpu *vcpu,
                quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
                role.quadrant = quadrant;
        }
-       for_each_gfn_sp(vcpu->kvm, sp, gfn) {
-               if (is_obsolete_sp(vcpu->kvm, sp))
-                       continue;
-
+       for_each_gfn_valid_sp(vcpu->kvm, sp, gfn) {
                if (!need_sync && sp->unsync)
                        need_sync = true;
 
-- 
1.8.3.1