diff mbox series

[RFC,09/14] KVM: x86/MMU: Only make pages available on Shadow MMU fault

Message ID 20221221222418.3307832-10-bgardon@google.com
State New
Headers
Series KVM: x86/MMU: Formalize the Shadow MMU |

Commit Message

Ben Gardon Dec. 21, 2022, 10:24 p.m. UTC 
  Now that the Shadow MMU has been factored out of mmu.c and the naming
sheme has been cleaned up, it's clear that there's an unnecessary
operation in direct_page_fault(). Since the MMU page quota is only
applied to the Shadow MMU, there's no point to calling
kvm_shadow_mmu_make_pages_available on a fault where the TDP MMU is
going to handle installing new TDP PTEs.

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Comments

David Matlack Dec. 29, 2022, 6:30 p.m. UTC | #1 
On Wed, Dec 21, 2022 at 2:24 PM Ben Gardon <bgardon@google.com> wrote:
>
> Now that the Shadow MMU has been factored out of mmu.c and the naming
> sheme has been cleaned up, it's clear that there's an unnecessary
> operation in direct_page_fault(). Since the MMU page quota is only
> applied to the Shadow MMU, there's no point to calling
> kvm_shadow_mmu_make_pages_available on a fault where the TDP MMU is
> going to handle installing new TDP PTEs.

Jinx! An equivalent change recently went into kvm/queue:

https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?h=queue&id=1290f90e77186bf8a06a3a35ebf254f5b004676b
diff mbox series

Patch

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index bacb519ba7b4..568b36de9eeb 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1469,14 +1469,14 @@  static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
 	if (is_page_fault_stale(vcpu, fault, mmu_seq))
 		goto out_unlock;
 
-	r = kvm_shadow_mmu_make_pages_available(vcpu);
-	if (r)
-		goto out_unlock;
-
 	if (is_tdp_mmu_fault)
 		r = kvm_tdp_mmu_map(vcpu, fault);
-	else
+	else {
+		r = kvm_shadow_mmu_make_pages_available(vcpu);
+		if (r)
+			goto out_unlock;
 		r = kvm_shadow_mmu_direct_map(vcpu, fault);
+	}
 
 out_unlock:
 	if (is_tdp_mmu_fault)