[PATCH 2/2] KVM: x86: Fix access to vcpu->arch.apic when the irqchip is not in kernel

From: Jue Wang <juew@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Jim Mattson <jmattson@google.com>,
	Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Joerg Roedel <joro@8bytes.org>,
	David Matlack <dmatlack@google.com>,
	Tony Luck <tony.luck@intel.com>,
	kvm@vger.kernel.org, Jiaqi Yan <jiaqiyan@google.com>,
	Jue Wang <juew@google.com>
Subject: [PATCH 2/2] KVM: x86: Fix access to vcpu->arch.apic when the irqchip is not in kernel
Date: Fri,  1 Jul 2022 09:50:45 -0700	[thread overview]
Message-ID: <20220701165045.4074471-2-juew@google.com> (raw)
In-Reply-To: <20220701165045.4074471-1-juew@google.com>

Fix an access to vcpu->arch.apic when KVM_X86_SETUP_MCE is called
without KVM_CREATE_IRQCHIP called or KVM_CAP_SPLIT_IRQCHIP is
enabled.

Fixes: 4b903561ec49 ("KVM: x86: Add Corrected Machine Check Interrupt (CMCI) emulation to lapic.")
Signed-off-by: Jue Wang <juew@google.com>
---
 arch/x86/kvm/x86.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4322a1365f74..d81020dd0fea 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4820,8 +4820,9 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
 		if (mcg_cap & MCG_CMCI_P)
 			vcpu->arch.mci_ctl2_banks[bank] = 0;
 	}
-	vcpu->arch.apic->nr_lvt_entries =
-		KVM_APIC_MAX_NR_LVT_ENTRIES - !(mcg_cap & MCG_CMCI_P);
+	if (vcpu->arch.apic)
+		vcpu->arch.apic->nr_lvt_entries =
+			KVM_APIC_MAX_NR_LVT_ENTRIES - !(mcg_cap & MCG_CMCI_P);
 
 	static_call(kvm_x86_setup_mce)(vcpu);
 out:
-- 
2.37.0.rc0.161.g10f37bed90-goog

