KVM: SMP: Add vcpu_id field in struct vcpu

This patch adds a `vcpu_id' field in `struct vcpu', so we can
differentiate BSP and APs without pointer comparison or arithmetic.

Signed-off-by: Qing He <qing.he@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

drivers/kvm/kvm_main.c

@@ -2355,6 +2355,7 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, int n)
 		goto out;
 
 	vcpu = &kvm->vcpus[n];
+	vcpu->vcpu_id = n;
 
 	mutex_lock(&vcpu->mutex);