KVM: remove kvm_vcpu_compatible

The new created_vcpus field makes it possible to avoid the race between
irqchip and VCPU creation in a much nicer way; just check under kvm->lock
whether a VCPU has already been created.

We can then remove KVM_APIC_ARCHITECTURE too, because at this point the
symbol is only governing the default definition of kvm_vcpu_compatible.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

5 files changed, 3 insertions, 22 deletions

diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 639a6e34500c..ab8e32f7b9a8 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -32,7 +32,6 @@ config KVM
         select HAVE_KVM_IRQ_BYPASS
         select HAVE_KVM_IRQ_ROUTING
         select HAVE_KVM_EVENTFD
-        select KVM_APIC_ARCHITECTURE
         select KVM_ASYNC_PF
         select USER_RETURN_NOTIFIER
         select KVM_MMIO
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bf227212aebb..ab2f45a50bb5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3774,7 +3774,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
                 r = -EEXIST;
                 if (irqchip_in_kernel(kvm))
                         goto split_irqchip_unlock;
-                if (atomic_read(&kvm->online_vcpus))
+                if (kvm->created_vcpus)
                         goto split_irqchip_unlock;
                 r = kvm_setup_empty_irq_routing(kvm);
                 if (r)
@@ -3839,7 +3839,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
                 if (kvm->arch.vpic)
                         goto create_irqchip_unlock;
                 r = -EINVAL;
-                if (atomic_read(&kvm->online_vcpus))
+                if (kvm->created_vcpus)
                         goto create_irqchip_unlock;
                 r = -ENOMEM;
                 vpic = kvm_create_pic(kvm);
@@ -3995,7 +3995,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
         case KVM_SET_BOOT_CPU_ID:
                 r = 0;
                 mutex_lock(&kvm->lock);
-                if (atomic_read(&kvm->online_vcpus) != 0)
+                if (kvm->created_vcpus)
                         r = -EBUSY;
                 else
                         kvm->arch.bsp_vcpu_id = arg;
@@ -7639,11 +7639,6 @@ bool kvm_vcpu_is_bsp(struct kvm_vcpu *vcpu)
         return (vcpu->arch.apic_base & MSR_IA32_APICBASE_BSP) != 0;
 }
 
-bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu)
-{
-        return irqchip_in_kernel(vcpu->kvm) == lapic_in_kernel(vcpu);
-}
-
 struct static_key kvm_no_apic_vcpu __read_mostly;
 EXPORT_SYMBOL_GPL(kvm_no_apic_vcpu);
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 63c6ab30bc81..0640ee92b978 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1105,12 +1105,6 @@ static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
 
 #endif /* CONFIG_HAVE_KVM_EVENTFD */
 
-#ifdef CONFIG_KVM_APIC_ARCHITECTURE
-bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu);
-#else
-static inline bool kvm_vcpu_compatible(struct kvm_vcpu *vcpu) { return true; }
-#endif
-
 static inline void kvm_make_request(int req, struct kvm_vcpu *vcpu)
 {
         /*
diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
index e5d6108f5e85..b0cc1a34db27 100644
--- a/virt/kvm/Kconfig
+++ b/virt/kvm/Kconfig
@@ -16,9 +16,6 @@ config HAVE_KVM_EVENTFD
        bool
        select EVENTFD
 
-config KVM_APIC_ARCHITECTURE
-       bool
-
 config KVM_MMIO
        bool
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 15b757ae64e1..ef54b4c31792 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2368,10 +2368,6 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
                 goto vcpu_destroy;
 
         mutex_lock(&kvm->lock);
-        if (!kvm_vcpu_compatible(vcpu)) {
-                r = -EINVAL;
-                goto unlock_vcpu_destroy;
-        }
         if (kvm_get_vcpu_by_id(kvm, id)) {
                 r = -EEXIST;
                 goto unlock_vcpu_destroy;