2 files changed, 20 insertions, 5 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ddb08581c64d..0c8453fa9f9e 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2328,6 +2328,7 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low,
 int kvm_add_user_return_msr(u32 msr);
 int kvm_find_user_return_msr(u32 msr);
 int kvm_set_user_return_msr(unsigned index, u64 val, u64 mask);
+void kvm_user_return_msr_update_cache(unsigned int index, u64 val);
 
 static inline bool kvm_is_supported_user_return_msr(u32 msr)
 {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8f3292ccdca4..1133bec79a82 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -636,6 +636,15 @@ static void kvm_user_return_msr_cpu_online(void)
 	}
 }
 
+static void kvm_user_return_register_notifier(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);
@@ -649,15 +658,20 @@ 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_register_notifier(msrs);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(kvm_set_user_return_msr);
 
+void kvm_user_return_msr_update_cache(unsigned int slot, u64 value)
+{
+	struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs);
+
+	msrs->values[slot].curr = value;
+	kvm_user_return_register_notifier(msrs);
+}
+EXPORT_SYMBOL_GPL(kvm_user_return_msr_update_cache);
+
 static void drop_user_return_notifiers(void)
 {
 	struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs);