Commit 04dc4e6c authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Move "invalid" check out of kvm_tdp_mmu_get_root() 



Move the check for an invalid root out of kvm_tdp_mmu_get_root() and into
the one place it actually matters, tdp_mmu_next_root(), as the other user
already has an implicit validity check.  A future bug fix will need to
get references to invalid roots to honor mmu_notifier requests; there's
no point in forcing what will be a common path to open code getting a
reference to a root.

No functional change intended.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211215011557.399940-3-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 83b83a02

arch/x86/kvm/mmu/tdp_mmu.c

+10 −2
Original line number Diff line number Diff line
@@ -121,9 +121,14 @@ static struct kvm_mmu_page *tdp_mmu_next_root(struct kvm *kvm, 
		next_root = list_first_or_null_rcu(&kvm->arch.tdp_mmu_roots,

						   typeof(*next_root), link);



	while (next_root && !kvm_tdp_mmu_get_root(kvm, next_root))

	while (next_root) {

		if (!next_root->role.invalid &&

		    kvm_tdp_mmu_get_root(kvm, next_root))

			break;



		next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots,

				&next_root->link, typeof(*next_root), link);

	}



	rcu_read_unlock();
@@ -200,7 +205,10 @@ hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu) 


	role = page_role_for_level(vcpu, vcpu->arch.mmu->shadow_root_level);



	/* Check for an existing root before allocating a new one. */

	/*

	 * Check for an existing root before allocating a new one.  Note, the

	 * role check prevents consuming an invalid root.

	 */

	for_each_tdp_mmu_root(kvm, root, kvm_mmu_role_as_id(role)) {

		if (root->role.word == role.word &&

		    kvm_tdp_mmu_get_root(kvm, root))

arch/x86/kvm/mmu/tdp_mmu.h

+0 −3
Original line number Diff line number Diff line
@@ -10,9 +10,6 @@ hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(struct kvm_vcpu *vcpu); 
__must_check static inline bool kvm_tdp_mmu_get_root(struct kvm *kvm,

						     struct kvm_mmu_page *root)

{

	if (root->role.invalid)

		return false;



	return refcount_inc_not_zero(&root->tdp_mmu_root_count);

}