linux-kernel - [PATCH 3/4] KVM: x86: pending exception must be be injected even with an injected event

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Date:   Thu, 25 Feb 2021 17:41:34 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Ingo Molnar <mingo@...hat.com>,
        linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
        64-BIT)), Jim Mattson <jmattson@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Wanpeng Li <wanpengli@...cent.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH 3/4] KVM: x86: pending exception must be be injected even with an injected event

Injected events should not block a pending exception, but rather,
should either be lost or be delivered to the nested hypervisor as part of
exitintinfo/IDT_VECTORING_INFO
(if nested hypervisor intercepts the pending exception)

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/kvm/svm/nested.c | 7 ++++++-
 arch/x86/kvm/vmx/nested.c | 9 +++++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 881e3954d753b..4c82abce0ea0c 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1024,7 +1024,12 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu)
 	}
 
 	if (vcpu->arch.exception.pending) {
-		if (block_nested_events)
+		/*
+		 * Only pending nested run can block an pending exception
+		 * Otherwise an injected NMI/interrupt should either be
+		 * lost or delivered to the nested hypervisor in EXITINTINFO
+		 * */
+		if (svm->nested.nested_run_pending)
                         return -EBUSY;
 		if (!nested_exit_on_exception(svm))
 			return 0;
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index b34e284bfa62a..20ed1a351b2d9 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3810,9 +3810,14 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
 
 	/*
 	 * Process any exceptions that are not debug traps before MTF.
+	 *
+	 * Note that only pending nested run can block an pending exception
+	 * Otherwise an injected NMI/interrupt should either be
+	 * lost or delivered to the nested hypervisor in EXITINTINFO
 	 */
+
 	if (vcpu->arch.exception.pending && !vmx_pending_dbg_trap(vcpu)) {
-		if (block_nested_events)
+		if (vmx->nested.nested_run_pending)
 			return -EBUSY;
 		if (!nested_vmx_check_exception(vcpu, &exit_qual))
 			goto no_vmexit;
@@ -3829,7 +3834,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu)
 	}
 
 	if (vcpu->arch.exception.pending) {
-		if (block_nested_events)
+		if (vmx->nested.nested_run_pending)
 			return -EBUSY;
 		if (!nested_vmx_check_exception(vcpu, &exit_qual))
 			goto no_vmexit;
-- 
2.26.2