[PATCH v1 02/22] KVM: x86: check against irqchip_mode in kvm_set_routing_entry()

[David Hildenbrand <david@redhat.com>]

Let's replace the checks for pic_in_kernel() and ioapic_in_kernel() by
checks against irqchip_mode. Add another state, indicating that the
caller is currently initializing the irqchip.

This is necessary to switch pic_in_kernel() and ioapic_in_kernel() to
irqchip_mode, too.

Also make sure that creation of any route is only possible if we have
a lapic in kernel (irqchip_in_kernel()) or if we are currently
inititalizing the irqchip.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/irq.h              |  2 +-
 arch/x86/kvm/irq_comm.c         | 12 ++++++------
 arch/x86/kvm/x86.c              |  7 ++++++-
 4 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 74ef58c..164e544 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -727,6 +727,7 @@ struct kvm_hv {
 
 enum kvm_irqchip_mode {
 	KVM_IRQCHIP_NONE,
+	KVM_IRQCHIP_INIT_IN_PROGRESS, /* temporarily set during creation */
 	KVM_IRQCHIP_KERNEL,       /* created with KVM_CREATE_IRQCHIP */
 	KVM_IRQCHIP_SPLIT,        /* created with KVM_CAP_SPLIT_IRQCHIP */
 };
diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h
index 40d5b2c..7fa2480 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -103,7 +103,7 @@ static inline int irqchip_kernel(struct kvm *kvm)
 
 static inline int irqchip_in_kernel(struct kvm *kvm)
 {
-	bool ret = kvm->arch.irqchip_mode != KVM_IRQCHIP_NONE;
+	bool ret = kvm->arch.irqchip_mode > KVM_IRQCHIP_INIT_IN_PROGRESS;
 
 	/* Matches with wmb after initializing kvm->irq_routing. */
 	smp_rmb();
diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index 6825cd3..0a026f8 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -282,24 +282,24 @@ int kvm_set_routing_entry(struct kvm *kvm,
 	int delta;
 	unsigned max_pin;
 
+	/* also allow creation of routes during KVM_IRQCHIP_INIT_IN_PROGRESS */
+	if (kvm->arch.irqchip_mode == KVM_IRQCHIP_NONE)
+		goto out;
+
 	switch (ue->type) {
 	case KVM_IRQ_ROUTING_IRQCHIP:
+		if (irqchip_split(kvm))
+			goto out;
 		delta = 0;
 		switch (ue->u.irqchip.irqchip) {
 		case KVM_IRQCHIP_PIC_SLAVE:
 			delta = 8;
 			/* fall through */
 		case KVM_IRQCHIP_PIC_MASTER:
-			if (!pic_in_kernel(kvm))
-				goto out;
-
 			e->set = kvm_set_pic_irq;
 			max_pin = PIC_NUM_PINS;
 			break;
 		case KVM_IRQCHIP_IOAPIC:
-			if (!ioapic_in_kernel(kvm))
-				goto out;
-
 			max_pin = KVM_IOAPIC_NUM_PINS;
 			e->set = kvm_set_ioapic_irq;
 			break;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1faf620..fa8cceb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3934,9 +3934,12 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 			goto split_irqchip_unlock;
 		if (kvm->created_vcpus)
 			goto split_irqchip_unlock;
+		kvm->arch.irqchip_mode = KVM_IRQCHIP_INIT_IN_PROGRESS;
 		r = kvm_setup_empty_irq_routing(kvm);
-		if (r)
+		if (r) {
+			kvm->arch.irqchip_mode = KVM_IRQCHIP_NONE;
 			goto split_irqchip_unlock;
+		}
 		/* Pairs with irqchip_in_kernel. */
 		smp_wmb();
 		kvm->arch.irqchip_mode = KVM_IRQCHIP_SPLIT;
@@ -4024,8 +4027,10 @@ long kvm_arch_vm_ioctl(struct file *filp,
 			goto create_irqchip_unlock;
 		}
 
+		kvm->arch.irqchip_mode = KVM_IRQCHIP_INIT_IN_PROGRESS;
 		r = kvm_setup_default_irq_routing(kvm);
 		if (r) {
+			kvm->arch.irqchip_mode = KVM_IRQCHIP_NONE;
 			mutex_lock(&kvm->slots_lock);
 			mutex_lock(&kvm->irq_lock);
 			kvm_ioapic_destroy(kvm);
-- 
2.9.3