linux-kernel - [PATCH v2 16/22] KVM: nVMX: Prioritize SMI over nested IRQ/NMI

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Date:   Sat, 25 Apr 2020 03:01:48 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     wei.huang2@....com, cavery@...hat.com, vkuznets@...hat.com,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Oliver Upton <oupton@...gle.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: [PATCH v2 16/22] KVM: nVMX: Prioritize SMI over nested IRQ/NMI

From: Sean Christopherson <sean.j.christopherson@...el.com>

Check for an unblocked SMI in vmx_check_nested_events() so that pending
SMIs are correctly prioritized over IRQs and NMIs when the latter events
will trigger VM-Exit.  This also fixes an issue where an SMI that was
marked pending while processing a nested VM-Enter wouldn't trigger an
immediate exit, i.e. would be incorrectly delayed until L2 happened to
take a VM-Exit.

Fixes: 64d6067057d96 ("KVM: x86: stubs for SMM support")
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
Message-Id: <20200423022550.15113-10-sean.j.christopherson@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/vmx/nested.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 188ff4cfdbaf..2c36f3f53108 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3750,6 +3750,12 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
 		return 0;
 	}
 
+	if (vcpu->arch.smi_pending && !is_smm(vcpu)) {
+		if (block_nested_events)
+			return -EBUSY;
+		goto no_vmexit;
+	}
+
 	if (vcpu->arch.nmi_pending && !vmx_nmi_blocked(vcpu)) {
 		if (block_nested_events)
 			return -EBUSY;
-- 
2.18.2