[RFC PATCH 14/22] KVM: x86: Introduce kvm_user_return_notifier_register()

[Mingwei Zhang]

From: Jim Mattson <jmattson@xxxxxxxxxx>

Factor out user return notifier registration logic from
kvm_set_user_return_msr() into a separate helper function to prepare
for the registration of KVM's user return notifier from
kvm_load_guest_aperfmperf().

No functional change intended.

Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
 arch/x86/kvm/x86.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index acfa9ecc5bc36..6df8f21b83eb1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -637,6 +637,15 @@ static void kvm_user_return_msr_cpu_online(void)
 	}
 }
 
+static void kvm_user_return_notifier_register(struct kvm_user_return_msrs *msrs)
+{
+	if (!msrs->registered) {
+		msrs->urn.on_user_return = kvm_on_user_return;
+		user_return_notifier_register(&msrs->urn);
+		msrs->registered = true;
+	}
+}
+
 int kvm_set_user_return_msr(unsigned slot, u64 value, u64 mask)
 {
 	struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs);
@@ -650,11 +659,7 @@ int kvm_set_user_return_msr(unsigned slot, u64 value, u64 mask)
 		return 1;
 
 	msrs->values[slot].curr = value;
-	if (!msrs->registered) {
-		msrs->urn.on_user_return = kvm_on_user_return;
-		user_return_notifier_register(&msrs->urn);
-		msrs->registered = true;
-	}
+	kvm_user_return_notifier_register(msrs);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_set_user_return_msr);
-- 
2.47.0.371.ga323438b13-goog