diff mbox series

[v8,05/11] KVM: x86/mmu: Rearrange kvm_{test_,}age_gfn

Message ID 20241105184333.2305744-6-jthoughton@google.com (mailing list archive)
State New
Headers show
Series KVM: x86/mmu: Age sptes locklessly | expand

Commit Message

James Houghton Nov. 5, 2024, 6:43 p.m. UTC 
Reorder the TDP MMU check to be first for both kvm_test_age_gfn and
kvm_age_gfn. For kvm_test_age_gfn, this allows us to completely avoid
needing to grab the MMU lock when the TDP MMU reports that the page is
young. Do the same for kvm_age_gfn merely for consistency.

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

Comments

Yu Zhao Nov. 5, 2024, 6:46 p.m. UTC | #1 
On Tue, Nov 5, 2024 at 11:43 AM James Houghton <jthoughton@google.com> wrote:
>
> Reorder the TDP MMU check to be first for both kvm_test_age_gfn and
> kvm_age_gfn. For kvm_test_age_gfn, this allows us to completely avoid
> needing to grab the MMU lock when the TDP MMU reports that the page is
> young. Do the same for kvm_age_gfn merely for consistency.
>
> Signed-off-by: James Houghton <jthoughton@google.com>

Acked-by: Yu Zhao <yuzhao@google.com>
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 26797ccd34d8..793565a3a573 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1586,15 +1586,15 @@  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;
 }
 
@@ -1602,15 +1602,15 @@  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;
 }