linux-kernel - [PATCH 02/10] KVM: nVMX: Drop a superfluous WARN on reflecting EXTERNAL

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Message-Id: <20200312184521.24579-3-sean.j.christopherson@intel.com>
Date:   Thu, 12 Mar 2020 11:45:13 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>
Subject: [PATCH 02/10] KVM: nVMX: Drop a superfluous WARN on reflecting EXTERNAL_INTERRUPT

Drop the WARN in nested_vmx_reflect_vmexit() that fires if KVM attempts
to reflect an external interrupt.  nested_vmx_exit_reflected() is now
called from nested_vmx_reflect_vmexit() and unconditionally returns
false for EXTERNAL_INTERRUPT, i.e. barring a compiler or major CPU bug,
the WARN will never fire.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/vmx/nested.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
index 6bc379cf4755..8f5ff3e259c9 100644
--- a/arch/x86/kvm/vmx/nested.h
+++ b/arch/x86/kvm/vmx/nested.h
@@ -84,12 +84,11 @@ static inline bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu,
 		return false;
 
 	/*
-	 * At this point, the exit interruption info in exit_intr_info
-	 * is only valid for EXCEPTION_NMI exits.  For EXTERNAL_INTERRUPT
-	 * we need to query the in-kernel LAPIC.
+	 * vmcs.VM_EXIT_INTR_INFO is only valid for EXCEPTION_NMI exits.  For
+	 * EXTERNAL_INTERRUPT, the value for vmcs12->vm_exit_intr_info would
+	 * need to be synthesized by querying the in-kernel LAPIC, but external
+	 * interrupts are never reflected to L1 so it's a non-issue.
 	 */
-	WARN_ON(exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT);
-
 	exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
 	if ((exit_intr_info &
 	     (INTR_INFO_VALID_MASK | INTR_INFO_DELIVER_CODE_MASK)) ==
-- 
2.24.1