KVM: x86: dynamic kvm_apic_map

x2APIC supports up to 2^32-1 LAPICs, but most guest in coming years will
probably has fewer VCPUs.  Dynamic size saves memory at the cost of
turning one constant into a variable.

apic_map mutex had to be moved before allocation to avoid races with cpu
hotplug.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 336ba51..8d81113 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -200,7 +200,7 @@
 	return lapic_in_kernel(vcpu) && test_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
 }
 
-static inline int kvm_apic_id(struct kvm_lapic *apic)
+static inline u32 kvm_apic_id(struct kvm_lapic *apic)
 {
 	return (kvm_lapic_get_reg(apic, APIC_ID) >> 24) & 0xff;
 }