KVM: x86/mmu: Allow parallel page faults for the TDP MMU

Make the last few changes necessary to enable the TDP MMU to handle page faults in parallel while holding the mmu_lock in read mode. Reviewed-by: Peter Feiner <[email protected]> Signed-off-by: Ben Gardon <[email protected]> Message-Id: <[email protected]> Signed-off-by: Paolo Bonzini <[email protected]>
khadas · Feb 4, 2021 · a2855af · a2855af
1 parent e25f0e0
commit a2855af
Showing 1 changed file with 10 additions and 2 deletions.
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
@@ -3718,7 +3718,12 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 		return r;
 
 	r = RET_PF_RETRY;
-	write_lock(&vcpu->kvm->mmu_lock);
+
+	if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
+		read_lock(&vcpu->kvm->mmu_lock);
+	else
+		write_lock(&vcpu->kvm->mmu_lock);
+
 	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
 		goto out_unlock;
 	r = make_mmu_pages_available(vcpu);
@@ -3733,7 +3738,10 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 				 prefault, is_tdp);
 
 out_unlock:
-	write_unlock(&vcpu->kvm->mmu_lock);
+	if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
+		read_unlock(&vcpu->kvm->mmu_lock);
+	else
+		write_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
 	return r;
 }