linux-kernel - [PATCH 17/21] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after potential VM-Exit

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Message-Id: <20220311032801.3467418-18-seanjc@google.com>
Date:   Fri, 11 Mar 2022 03:27:57 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.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, Oliver Upton <oupton@...gle.com>,
        Peter Shier <pshier@...gle.com>
Subject: [PATCH 17/21] KVM: x86: Evaluate ability to inject SMI/NMI/IRQ after
 potential VM-Exit

Determine whether or not new events can be injected after checking nested
events.  If a VM-Exit occurred during nested event handling, any previous
event that needed re-injection is gone from's KVM perspective; the event
is captured in the vmc*12 VM-Exit information, but doesn't exist in terms
of what needs to be done for entry to L1.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/x86.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c1cd2166fe22..327a935712fb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9310,7 +9310,7 @@ static void kvm_inject_exception(struct kvm_vcpu *vcpu)
 
 static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
 {
-	bool can_inject = !kvm_event_needs_reinjection(vcpu);
+	bool can_inject;
 	int r;
 
 	/*
@@ -9375,7 +9375,13 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
 	if (r < 0)
 		goto out;
 
-	/* try to inject new event if pending */
+	/*
+	 * New events, other than exceptions, cannot be injected if KVM needs
+	 * to re-inject a previous event.  See above comments on re-injecting
+	 * for why pending exceptions get priority.
+	 */
+	can_inject = !kvm_event_needs_reinjection(vcpu);
+
 	if (vcpu->arch.exception.pending) {
 		trace_kvm_inj_exception(vcpu->arch.exception.vector,
 					vcpu->arch.exception.has_error_code,
-- 
2.35.1.723.g4982287a31-goog