[PATCH v2] KVM: x86: fix user triggerable warning in kvm_apic_accept_events()

[David Hildenbrand]

If we already entered/are about to enter SMM, don't allow switching to
INIT/SIPI_RECEIVED, otherwise the next call to kvm_apic_accept_events()
will report a warning.

Same applies if we are already in MP state INIT_RECEIVED and SMM is
requested to be turned on. Refuse to set the VCPU events in this case.

Fixes: cd7764fe9f73 ("KVM: x86: latch INITs while in system management mode")
Cc: sta...@vger.kernel.org # 4.2+
Reported-by: Dmitry Vyukov <dvyu...@google.com>
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 arch/x86/kvm/x86.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1faf620..f139c07 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3127,6 +3127,12 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct 
kvm_vcpu *vcpu,
            (events->exception.nr > 31 || events->exception.nr == NMI_VECTOR))
                return -EINVAL;
 
+       /* INITs are latched while in SMM */
+       if (events->flags & KVM_VCPUEVENT_VALID_SMM &&
+           (events->smi.smm || events->smi.pending) &&
+           vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED)
+               return -EINVAL;
+
        process_nmi(vcpu);
        vcpu->arch.exception.pending = events->exception.injected;
        vcpu->arch.exception.nr = events->exception.nr;
@@ -7355,6 +7361,12 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu 
*vcpu,
            mp_state->mp_state != KVM_MP_STATE_RUNNABLE)
                return -EINVAL;
 
+       /* INITs are latched while in SMM */
+       if ((is_smm(vcpu) || vcpu->arch.smi_pending) &&
+           (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED ||
+            mp_state->mp_state == KVM_MP_STATE_INIT_RECEIVED))
+               return -EINVAL;
+
        if (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED) {
                vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED;
                set_bit(KVM_APIC_SIPI, &vcpu->arch.apic->pending_events);
-- 
2.9.3