From: David Hildenbrand <david@redhat.com>
Date: Fri, 7 Apr 2017 08:50:21 +0000 (+0200)
Subject: KVM: x86: check against irqchip_mode in pic_in_kernel()
X-Git-Tag: v4.12-rc1~68^2~50
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=19d25a0e474b0c69272e17cb6a9106c25eb27c82;p=karo-tx-linux.git

KVM: x86: check against irqchip_mode in pic_in_kernel()

Let's avoid checking against kvm->arch.vpic. We have kvm->arch.irqchip_mode
for that now.

KVM_IRQCHIP_KERNEL implies a fully inititalized pic, while kvm->arch.vpic
might temporarily be set but invalidated again if e.g. kvm_ioapic_init()
fails when setting KVM_CREATE_IRQCHIP. Although current users seem to be
fine, this avoids future bugs.

Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---

diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index 59e05febc8fb..26d8dd4a4323 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -85,10 +85,11 @@ static inline struct kvm_pic *pic_irqchip(struct kvm *kvm)
 
 static inline int pic_in_kernel(struct kvm *kvm)
 {
-	int ret;
+	int mode = kvm->arch.irqchip_mode;
 
-	ret = (pic_irqchip(kvm) != NULL);
-	return ret;
+	/* Matches smp_wmb() when setting irqchip_mode */
+	smp_rmb();
+	return mode == KVM_IRQCHIP_KERNEL;
 }
 
 static inline int irqchip_split(struct kvm *kvm)