[PATCH 09/21] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU is not in WFS

Sean Christopherson
2022-03-11T03:28:57Z

Fall through to handling other pending exception/events for L2 if SIPI
is pending while the CPU is not in Wait-for-SIPI. KVM correctly ignores
the event, but incorrectly returns immediately, e.g. a SIPI coincident
with another event could lead to KVM incorrectly routing the event to L1
instead of L2.

Fixes: bf0cd88ce363 ("KVM: x86: emulate wait-for-SIPI and SIPI-VMExit")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/nested.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 53ac6ebb3b3b..b22089ebfe76 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3911,10 +3911,12 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
return -EBUSY;

clear_bit(KVM_APIC_SIPI, &apic->pending_events);
- if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED)
+ if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) {
nested_vmx_vmexit(vcpu, EXIT_REASON_SIPI_SIGNAL, 0,
apic->sipi_vector & 0xFFUL);
- return 0;
+ return 0;
+ }
+ /* Fallthrough, the SIPI is completely ignored. */
}

/*
--
2.35.1.723.g4982287a31-goog