7 files changed, 19 insertions, 21 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 84c8489531bb..f5bddf92faba 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -728,7 +728,6 @@ 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 0edd22c3344c..d5005cc26521 100644
--- a/arch/x86/kvm/irq.h
+++ b/arch/x86/kvm/irq.h
@@ -111,7 +111,7 @@ static inline int irqchip_in_kernel(struct kvm *kvm)
 
         /* Matches smp_wmb() when setting irqchip_mode */
         smp_rmb();
-        return mode > KVM_IRQCHIP_INIT_IN_PROGRESS;
+        return mode != KVM_IRQCHIP_NONE;
 }
 
 void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/irq_comm.c b/arch/x86/kvm/irq_comm.c
index 4517a4c2ac3a..3cc3b2d130a0 100644
--- a/arch/x86/kvm/irq_comm.c
+++ b/arch/x86/kvm/irq_comm.c
@@ -274,16 +274,19 @@ void kvm_fire_mask_notifiers(struct kvm *kvm, unsigned irqchip, unsigned pin,
         srcu_read_unlock(&kvm->irq_srcu, idx);
 }
 
+bool kvm_arch_can_set_irq_routing(struct kvm *kvm)
+{
+        return irqchip_in_kernel(kvm);
+}
+
 int kvm_set_routing_entry(struct kvm *kvm,
                           struct kvm_kernel_irq_routing_entry *e,
                           const struct kvm_irq_routing_entry *ue)
 {
-        /* also allow creation of routes during KVM_IRQCHIP_INIT_IN_PROGRESS */
-        if (kvm->arch.irqchip_mode == KVM_IRQCHIP_NONE)
-                return -EINVAL;
-
-        /* Matches smp_wmb() when setting irqchip_mode */
-        smp_rmb();
+        /* We can't check irqchip_in_kernel() here as some callers are
+         * currently inititalizing the irqchip. Other callers should therefore
+         * check kvm_arch_can_set_irq_routing() before calling this function.
+         */
         switch (ue->type) {
         case KVM_IRQ_ROUTING_IRQCHIP:
                 if (irqchip_split(kvm))
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index be2ade58edb9..2fe9aa116288 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3919,14 +3919,9 @@ 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) {
-                        kvm->arch.irqchip_mode = KVM_IRQCHIP_NONE;
-                        /* Pairs with smp_rmb() when reading irqchip_mode */
-                        smp_wmb();
+                if (r)
                         goto split_irqchip_unlock;
-                }
                 /* Pairs with irqchip_in_kernel. */
                 smp_wmb();
                 kvm->arch.irqchip_mode = KVM_IRQCHIP_SPLIT;
@@ -4012,12 +4007,8 @@ 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;
-                        /* Pairs with smp_rmb() when reading irqchip_mode */
-                        smp_wmb();
                         kvm_ioapic_destroy(kvm);
                         kvm_pic_destroy(kvm);
                         goto create_irqchip_unlock;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a5bfffa8c8d4..25cf258a1c9b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1018,6 +1018,7 @@ static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq)
 #define KVM_MAX_IRQ_ROUTES 1024
 #endif
 
+bool kvm_arch_can_set_irq_routing(struct kvm *kvm);
 int kvm_set_irq_routing(struct kvm *kvm,
                         const struct kvm_irq_routing_entry *entries,
                         unsigned nr,
diff --git a/virt/kvm/irqchip.c b/virt/kvm/irqchip.c
index cc30d01a56be..31e40c9e81df 100644
--- a/virt/kvm/irqchip.c
+++ b/virt/kvm/irqchip.c
@@ -172,6 +172,11 @@ void __attribute__((weak)) kvm_arch_irq_routing_update(struct kvm *kvm)
 {
 }
 
+bool __weak kvm_arch_can_set_irq_routing(struct kvm *kvm)
+{
+        return true;
+}
+
 int kvm_set_irq_routing(struct kvm *kvm,
                         const struct kvm_irq_routing_entry *ue,
                         unsigned nr,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 035bc51f656f..6281cc2446d5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3075,6 +3075,8 @@ static long kvm_vm_ioctl(struct file *filp,
                 if (copy_from_user(&routing, argp, sizeof(routing)))
                         goto out;
                 r = -EINVAL;
+                if (!kvm_arch_can_set_irq_routing(kvm))
+                        goto out;
                 if (routing.nr > KVM_MAX_IRQ_ROUTES)
                         goto out;
                 if (routing.flags)
@@ -3090,11 +3092,8 @@ static long kvm_vm_ioctl(struct file *filp,
                                            routing.nr * sizeof(*entries)))
                                 goto out_free_irq_routing;
                 }
-                /* avoid races with KVM_CREATE_IRQCHIP on x86 */
-                mutex_lock(&kvm->lock);
                 r = kvm_set_irq_routing(kvm, entries, routing.nr,
                                         routing.flags);
-                mutex_unlock(&kvm->lock);
 out_free_irq_routing:
                 vfree(entries);
                 break;