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@xxxxxxxxxxxxxxx
>
> Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
> ---
> 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.1637799475.git.isaku.yamahata@xxxxxxxxx
> 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
>
