On Tue, Mar 22, 2022, Maxim Levitsky wrote:

This can cause various unexpected issues, since VM is partially destroyed at that point.

For example when AVIC is enabled, this causes avic_vcpu_load to access physical id page entry which is already freed by .vm_destroy.

Hmm, the SEV unbinding of ASIDs should be done after MMU teardown too (which your patch also does).

Fixes: 8221c1370056 ("svm: Manage vcpu load/unload when enable AVIC") Cc: stable@vger.kernel.org

Signed-off-by: Maxim Levitsky mlevitsk@redhat.com

arch/x86/kvm/x86.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index d3a9ce07a565..ba920e537ddf 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11759,20 +11759,15 @@ static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu) vcpu_put(vcpu); } -static void kvm_free_vcpus(struct kvm *kvm) +static void kvm_unload_vcpu_mmus(struct kvm *kvm) { unsigned long i; struct kvm_vcpu *vcpu;

• /*

• * Unpin any mmu pages first.
  

• */
  

  kvm_for_each_vcpu(i, vcpu, kvm) { kvm_clear_async_pf_completion_queue(vcpu); kvm_unload_vcpu_mmu(vcpu); }
• kvm_destroy_vcpus(kvm);

} void kvm_arch_sync_events(struct kvm *kvm) @@ -11878,11 +11873,12 @@ void kvm_arch_destroy_vm(struct kvm *kvm) __x86_set_memory_region(kvm, TSS_PRIVATE_MEMSLOT, 0, 0); mutex_unlock(&kvm->slots_lock); }

• kvm_unload_vcpu_mmus(kvm); static_call_cond(kvm_x86_vm_destroy)(kvm); kvm_free_msr_filter(srcu_dereference_check(kvm->arch.msr_filter, &kvm->srcu, 1)); kvm_pic_destroy(kvm); kvm_ioapic_destroy(kvm);

• kvm_free_vcpus(kvm);

• kvm_destroy_vcpus(kvm);

Rather than split kvm_free_vcpus(), can we instead move the call to svm_vm_destroy() by adding a second hook, .vm_teardown(), which is needed for TDX? I.e. keep VMX where it is by using vm_teardown, but effectively move SVM?

https://lore.kernel.org/all/1fa2d0db387a99352d44247728c5b8ae5f5cab4d.1637799...

kvfree(rcu_dereference_check(kvm->arch.apic_map, 1)); kfree(srcu_dereference_check(kvm->arch.pmu_event_filter, &kvm->srcu, 1)); kvm_mmu_uninit_vm(kvm); -- 2.26.3