kvm: make KVM_CAP_COALESCED_MMIO architecture agnostic

Remove code from architecture files that can be moved to virt/kvm, since there
is already common code for coalesced MMIO.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[Removed a pointless 'break' after 'return'.]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

arch/arm/kvm/arm.c

@@ -209,9 +209,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_IMMEDIATE_EXIT:
 		r = 1;
 		break;
-	case KVM_CAP_COALESCED_MMIO:
-		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
-		break;
 	case KVM_CAP_ARM_SET_DEVICE_ADDR:
 		r = 1;
 		break;

arch/mips/kvm/mips.c

@@ -1070,9 +1070,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_IMMEDIATE_EXIT:
 		r = 1;
 		break;
-	case KVM_CAP_COALESCED_MMIO:
-		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
-		break;
 	case KVM_CAP_NR_VCPUS:
 		r = num_online_cpus();
 		break;

arch/powerpc/kvm/powerpc.c

@@ -524,11 +524,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		/* We support this only for PR */
 		r = !hv_enabled;
 		break;
-#ifdef CONFIG_KVM_MMIO
-	case KVM_CAP_COALESCED_MMIO:
-		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
-		break;
-#endif
 #ifdef CONFIG_KVM_MPIC
 	case KVM_CAP_IRQ_MPIC:
 		r = 1;

arch/x86/kvm/x86.c

@@ -2690,9 +2690,6 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		 */
 		r = kvm_x86_ops->cpu_has_high_real_mode_segbase();
 		break;
-	case KVM_CAP_COALESCED_MMIO:
-		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
-		break;
 	case KVM_CAP_VAPIC:
 		r = !kvm_x86_ops->cpu_has_accelerated_tpr();
 		break;

virt/kvm/kvm_main.c

@@ -2918,6 +2918,10 @@ static long kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 	case KVM_CAP_IOEVENTFD_ANY_LENGTH:
 	case KVM_CAP_CHECK_EXTENSION_VM:
 		return 1;
+#ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
+	case KVM_CAP_COALESCED_MMIO:
+		return KVM_COALESCED_MMIO_PAGE_OFFSET;
+#endif
 #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING
 	case KVM_CAP_IRQ_ROUTING:
 		return KVM_MAX_IRQ_ROUTES;