KVM: x86/xen: Add kvm_xen_enabled static key
The code paths for Xen support are all fairly lightweight but if we hide
them behind this, they're even *more* lightweight for any system which
isn't actually hosting Xen guests.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
index 28e9c98..ec3d8f6 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -9,14 +9,20 @@
#ifndef __ARCH_X86_KVM_XEN_H__
#define __ARCH_X86_KVM_XEN_H__
+#include <linux/jump_label_ratelimit.h>
+
+extern struct static_key_false_deferred kvm_xen_enabled;
+
int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data);
int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc);
+void kvm_xen_destroy_vm(struct kvm *kvm);
static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)
{
- return kvm->arch.xen_hvm_config.flags &
- KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL;
+ return static_branch_unlikely(&kvm_xen_enabled.key) &&
+ (kvm->arch.xen_hvm_config.flags &
+ KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL);
}
#endif /* __ARCH_X86_KVM_XEN_H__ */