KVM: x86: introduce sched_in to kvm_x86_ops

sched_in preempt notifier is available for x86, allow its use in
specific virtualization technlogies as well.
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -771,6 +771,8 @@ struct kvm_x86_ops {
 	bool (*mpx_supported)(void);
 
 	int (*check_nested_events)(struct kvm_vcpu *vcpu, bool external_intr);
+
+	void (*sched_in)(struct kvm_vcpu *kvm, int cpu);
 };
 
 struct kvm_arch_async_pf {

arch/x86/kvm/svm.c

@@ -4305,6 +4305,10 @@ static void svm_handle_external_intr(struct kvm_vcpu *vcpu)
 	local_irq_enable();
 }
 
+static void svm_sched_in(struct kvm_vcpu *vcpu, int cpu)
+{
+}
+
 static struct kvm_x86_ops svm_x86_ops = {
 	.cpu_has_kvm_support = has_svm,
 	.disabled_by_bios = is_disabled,
@@ -4405,6 +4409,8 @@ static struct kvm_x86_ops svm_x86_ops = {
 
 	.check_intercept = svm_check_intercept,
 	.handle_external_intr = svm_handle_external_intr,
+
+	.sched_in = svm_sched_in,
 };
 
 static int __init svm_init(void)

arch/x86/kvm/vmx.c

@@ -8848,6 +8848,10 @@ static int vmx_check_intercept(struct kvm_vcpu *vcpu,
 	return X86EMUL_CONTINUE;
 }
 
+void vmx_sched_in(struct kvm_vcpu *vcpu, int cpu)
+{
+}
+
 static struct kvm_x86_ops vmx_x86_ops = {
 	.cpu_has_kvm_support = cpu_has_kvm_support,
 	.disabled_by_bios = vmx_disabled_by_bios,
@@ -8952,6 +8956,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
 	.mpx_supported = vmx_mpx_supported,
 
 	.check_nested_events = vmx_check_nested_events,
+
+	.sched_in = vmx_sched_in,
 };
 
 static int __init vmx_init(void)

arch/x86/kvm/x86.c

@@ -7173,6 +7173,7 @@ void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
 
 void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu)
 {
+	kvm_x86_ops->sched_in(vcpu, cpu);
 }
 
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)