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Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Tue, 14 Jun 2022 20:47:17 +0000
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Subject: [PATCH v2 08/21] KVM: nVMX: Ignore SIPI that arrives in L2 when vCPU
 is not in WFS
From:   Sean Christopherson <seanjc@google.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Oliver Upton <oupton@google.com>,
        Peter Shier <pshier@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

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 e794791a6bdd..d080bfca16ef 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3936,10 +3936,12 @@ 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. */
 	}
 
 	/*
-- 
2.36.1.476.g0c4daa206d-goog