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>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 80628f6..7fa62c7 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1253,7 +1253,7 @@
 	vcpu->regs[VCPU_REGS_RDX] = get_rdx_init_val();
 	vcpu->cr8 = 0;
 	vcpu->apic_base = 0xfee00000 | MSR_IA32_APICBASE_ENABLE;
-	if (vcpu == &vcpu->kvm->vcpus[0])
+	if (vcpu->vcpu_id == 0)
 		vcpu->apic_base |= MSR_IA32_APICBASE_BSP;
 
 	fx_init(vcpu);