linux-kernel - [PATCH 09/10] KVM: zero output of KVM_GET_VCPU

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Date:   Thu, 27 Oct 2022 12:49:43 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     mlevitsk@...hat.com, seanjc@...gle.com
Subject: [PATCH 09/10] KVM: zero output of KVM_GET_VCPU_EVENTS before filling in the struct

This allows making some fields optional, as will be the case soon
for SMM-related data.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/x86.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f6adb4145759..5959f74c5a0a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5056,16 +5056,15 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 	    ex->pending && ex->has_payload)
 		kvm_deliver_exception_payload(vcpu, ex);
 
+	memset(events, 0, sizeof(events));
+
 	/*
 	 * The API doesn't provide the instruction length for software
 	 * exceptions, so don't report them. As long as the guest RIP
 	 * isn't advanced, we should expect to encounter the exception
 	 * again.
 	 */
-	if (kvm_exception_is_soft(ex->vector)) {
-		events->exception.injected = 0;
-		events->exception.pending = 0;
-	} else {
+	if (!kvm_exception_is_soft(ex->vector)) {
 		events->exception.injected = ex->injected;
 		events->exception.pending = ex->pending;
 		/*
@@ -5085,15 +5084,13 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 	events->interrupt.injected =
 		vcpu->arch.interrupt.injected && !vcpu->arch.interrupt.soft;
 	events->interrupt.nr = vcpu->arch.interrupt.nr;
-	events->interrupt.soft = 0;
 	events->interrupt.shadow = static_call(kvm_x86_get_interrupt_shadow)(vcpu);
 
 	events->nmi.injected = vcpu->arch.nmi_injected;
 	events->nmi.pending = vcpu->arch.nmi_pending != 0;
 	events->nmi.masked = static_call(kvm_x86_get_nmi_mask)(vcpu);
-	events->nmi.pad = 0;
 
-	events->sipi_vector = 0; /* never valid when reporting to user space */
+	/* events->sipi_vector is never valid when reporting to user space */
 
 	events->smi.smm = is_smm(vcpu);
 	events->smi.pending = vcpu->arch.smi_pending;
@@ -5110,8 +5107,6 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu,
 		events->triple_fault.pending = kvm_test_request(KVM_REQ_TRIPLE_FAULT, vcpu);
 		events->flags |= KVM_VCPUEVENT_VALID_TRIPLE_FAULT;
 	}
-
-	memset(&events->reserved, 0, sizeof(events->reserved));
 }
 
 static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
-- 
2.31.1