linux-kernel - [PATCH 2/6] KVM: x86: decouple irqchip_in_kernel() and pic

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Date:   Thu, 24 Nov 2016 17:31:30 +0100
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 2/6] KVM: x86: decouple irqchip_in_kernel() and pic_irqchip()

irqchip_in_kernel() tried to save a bit by reusing pic_irqchip(), but it
just complicated the code.
Add kvm->arch.irqchip_kvm that matches kvm->arch.irqchip_split.
(Turning them into an exclusive type would be nicer.)

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/irq.h              | 13 +++++++------
 arch/x86/kvm/x86.c              |  3 ++-
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index bdde80731f49..929228ec2839 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -778,6 +778,7 @@ struct kvm_arch {
 
 	u64 disabled_quirks;
 
+	bool irqchip_kvm;
 	bool irqchip_split;
 	u8 nr_reserved_ioapic_pins;
 
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index 035731eb3897..8536be85d529 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -96,15 +96,16 @@ static inline int irqchip_split(struct kvm *kvm)
 	return kvm->arch.irqchip_split;
 }
 
+static inline int irqchip_kvm(struct kvm *kvm)
+{
+	return kvm->arch.irqchip_kvm;
+}
+
 static inline int irqchip_in_kernel(struct kvm *kvm)
 {
-	struct kvm_pic *vpic = pic_irqchip(kvm);
-	bool ret;
+	bool ret = irqchip_kvm(kvm) || irqchip_split(kvm);
 
-	ret = (vpic != NULL);
-	ret |= irqchip_split(kvm);
-
-	/* Read vpic before kvm->irq_routing.  */
+	/* Matches with wmb after initializing kvm->irq_routing. */
 	smp_rmb();
 	return ret;
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index dbed51045c37..dd8431a7e18b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3928,8 +3928,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
 			mutex_unlock(&kvm->slots_lock);
 			goto create_irqchip_unlock;
 		}
-		/* Write kvm->irq_routing before kvm->arch.vpic.  */
+		/* Write kvm->irq_routing before enabling irqchip_in_kernel. */
 		smp_wmb();
+		kvm->arch.irqchip_kvm = true;
 		kvm->arch.vpic = vpic;
 	create_irqchip_unlock:
 		mutex_unlock(&kvm->lock);
-- 
2.10.2