[PATCH v1 04/13] KVM: Advertise KVM_CAP_USERFAULT in KVM_CHECK_EXTENSION

[James Houghton]

Advertise support for KVM_CAP_USERFAULT when kvm_has_userfault() returns
true. Currently this is merely IS_ENABLED(CONFIG_HAVE_KVM_USERFAULT), so
it is somewhat redundant.

Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
 include/uapi/linux/kvm.h | 1 +
 virt/kvm/kvm_main.c      | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 641a2e580441..d9a135c895d7 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -936,6 +936,7 @@ struct kvm_enable_cap {
 #define KVM_CAP_PRE_FAULT_MEMORY 236
 #define KVM_CAP_X86_APIC_BUS_CYCLES_NS 237
 #define KVM_CAP_X86_GUEST_MODE 238
+#define KVM_CAP_USERFAULT 239
 
 struct kvm_irq_routing_irqchip {
 	__u32 irqchip;
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fa851704db94..b552cdef2850 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -4804,6 +4804,10 @@ static int kvm_vm_ioctl_check_extension_generic(struct kvm *kvm, long arg)
 #ifdef CONFIG_KVM_PRIVATE_MEM
 	case KVM_CAP_GUEST_MEMFD:
 		return !kvm || kvm_arch_has_private_mem(kvm);
+#endif
+#ifdef CONFIG_HAVE_KVM_USERFAULT
+	case KVM_CAP_USERFAULT:
+		return kvm_has_userfault(kvm);
 #endif
 	default:
 		break;
-- 
2.47.0.338.g60cca15819-goog