[PATCH v9 06/11] KVM: x86/mmu: Skip shadow MMU test_young if TDP MMU reports page as young

[James Houghton <jthoughton@google.com>]

Reorder the processing of the TDP MMU versus the shadow MMU when aging
SPTEs, and skip the shadow MMU entirely in the test-only case if the TDP
MMU reports that the page is young, i.e. completely avoid taking mmu_lock
if the TDP MMU SPTE is young.  Swap the order for the test-and-age helper
as well for consistency.

Signed-off-by: James Houghton <jthoughton@google.com>
Acked-by: Yu Zhao <yuzhao@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 1fa0f47eb6a5..4a9de4b330d7 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1592,15 +1592,15 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	bool young = false;
 
+	if (tdp_mmu_enabled)
+		young = kvm_tdp_mmu_age_gfn_range(kvm, range);
+
 	if (kvm_memslots_have_rmaps(kvm)) {
 		write_lock(&kvm->mmu_lock);
-		young = kvm_rmap_age_gfn_range(kvm, range, false);
+		young |= kvm_rmap_age_gfn_range(kvm, range, false);
 		write_unlock(&kvm->mmu_lock);
 	}
 
-	if (tdp_mmu_enabled)
-		young |= kvm_tdp_mmu_age_gfn_range(kvm, range);
-
 	return young;
 }
 
@@ -1608,15 +1608,15 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 {
 	bool young = false;
 
-	if (kvm_memslots_have_rmaps(kvm)) {
+	if (tdp_mmu_enabled)
+		young = kvm_tdp_mmu_test_age_gfn(kvm, range);
+
+	if (!young && kvm_memslots_have_rmaps(kvm)) {
 		write_lock(&kvm->mmu_lock);
-		young = kvm_rmap_age_gfn_range(kvm, range, true);
+		young |= kvm_rmap_age_gfn_range(kvm, range, true);
 		write_unlock(&kvm->mmu_lock);
 	}
 
-	if (tdp_mmu_enabled)
-		young |= kvm_tdp_mmu_test_age_gfn(kvm, range);
-
 	return young;
 }
 
-- 
2.48.1.362.g079036d154-goog