From: Sean Christopherson seanjc@google.com
commit 04dc4e6ce274fa729feda32aa957b27388a3870c upstream.
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: Sean Christopherson seanjc@google.com Message-Id: 20211215011557.399940-3-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/mmu/tdp_mmu.c | 12 ++++++++++-- arch/x86/kvm/mmu/tdp_mmu.h | 3 --- 2 files changed, 10 insertions(+), 5 deletions(-)
--- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -121,9 +121,14 @@ static struct kvm_mmu_page *tdp_mmu_next 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(stru
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)) --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -10,9 +10,6 @@ hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(stru __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); }