xen: Place vcpu_info structure into per-cpu memory

An experimental patch for Xen allows guests to place their vcpu_info
structs anywhere.  We try to use this to place the vcpu_info into the
PDA, which allows direct access.

If this works, then switch to using direct access operations for
irq_enable, disable, save_fl and restore_fl.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Keir Fraser <keir@xensource.com>
diff --git a/arch/i386/xen/xen-ops.h b/arch/i386/xen/xen-ops.h
index 4069be8..5b56f7f 100644
--- a/arch/i386/xen/xen-ops.h
+++ b/arch/i386/xen/xen-ops.h
@@ -38,7 +38,7 @@
 
 void __init xen_fill_possible_map(void);
 
-void xen_vcpu_setup(int cpu);
+void __init xen_setup_vcpu_info_placement(void);
 void xen_smp_prepare_boot_cpu(void);
 void xen_smp_prepare_cpus(unsigned int max_cpus);
 int xen_cpu_up(unsigned int cpu);