[PATCH 5.17 35/75] KVM: x86: avoid loading a vCPU after .vm_destroy was called

Greg Kroah-Hartman
2022-06-03T18:08:39Z

From: Maxim Levitsky <mlevitsk@redhat.com>

commit 6fcee03df6a1a3101a77344be37bb85c6142d56c upstream.

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.

Fixes: 8221c1370056 ("svm: Manage vcpu load/unload when enable AVIC")
Cc: stable@vger.kernel.org
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-2-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kvm/x86.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11655,20 +11655,15 @@ static void kvm_unload_vcpu_mmu(struct k
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)
@@ -11774,11 +11769,12 @@ 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);
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);