KVM: Add cpuid_update() callback to kvm_x86_ops

Sometime, we need to adjust some state in order to reflect guest CPUID
setting, e.g. if we don't expose rdtscp to guest, we won't want to enable
it on hardware. cpuid_update() is introduced for this purpose.

Also export kvm_find_cpuid_entry() for later use.

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4e7bbc4..e5ac21f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1574,6 +1574,7 @@
 	cpuid_fix_nx_cap(vcpu);
 	r = 0;
 	kvm_apic_set_version(vcpu);
+	kvm_x86_ops->cpuid_update(vcpu);
 
 out_free:
 	vfree(cpuid_entries);
@@ -1596,6 +1597,7 @@
 		goto out;
 	vcpu->arch.cpuid_nent = cpuid->nent;
 	kvm_apic_set_version(vcpu);
+	kvm_x86_ops->cpuid_update(vcpu);
 	return 0;
 
 out:
@@ -3733,6 +3735,7 @@
 	}
 	return best;
 }
+EXPORT_SYMBOL_GPL(kvm_find_cpuid_entry);
 
 int cpuid_maxphyaddr(struct kvm_vcpu *vcpu)
 {