[PATCH] paravirt: header and stubs for paravirtualisation

Create a paravirt.h header for all the critical operations which need to be
replaced with hypervisor calls, and include that instead of defining native
operations, when CONFIG_PARAVIRT.

This patch does the dumbest possible replacement of paravirtualized
instructions: calls through a "paravirt_ops" structure.  Currently these are
function implementations of native hardware: hypervisors will override the ops
structure with their own variants.

All the pv-ops functions are declared "fastcall" so that a specific
register-based ABI is used, to make inlining assember easier.

And:

+From: Andy Whitcroft <apw@shadowen.org>

The paravirt ops introduce a 'weak' attribute onto memory_setup().
Code ordering leads to the following warnings on x86:

    arch/i386/kernel/setup.c:651: warning: weak declaration of
                `memory_setup' after first use results in unspecified behavior

Move memory_setup() to avoid this.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>

include/asm-i386/processor.h

@@ -144,8 +144,8 @@ static inline void detect_ht(struct cpuinfo_x86 *c) {}
 #define X86_EFLAGS_VIP	0x00100000 /* Virtual Interrupt Pending */
 #define X86_EFLAGS_ID	0x00200000 /* CPUID detection flag */
 
-static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
-			   unsigned int *ecx, unsigned int *edx)
+static inline fastcall void native_cpuid(unsigned int *eax, unsigned int *ebx,
+					 unsigned int *ecx, unsigned int *edx)
 {
 	/* ecx is often an input as well as an output. */
 	__asm__("cpuid"
@@ -491,6 +491,12 @@ struct thread_struct {
 	.io_bitmap	= { [ 0 ... IO_BITMAP_LONGS] = ~0 },		\
 }
 
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+#else
+#define paravirt_enabled() 0
+#define __cpuid native_cpuid
+
 static inline void load_esp0(struct tss_struct *tss, struct thread_struct *thread)
 {
 	tss->esp0 = thread->esp0;
@@ -524,10 +530,13 @@ static inline void load_esp0(struct tss_struct *tss, struct thread_struct *threa
 			: /* no output */			\
 			:"r" (value))
 
+#define set_iopl_mask native_set_iopl_mask
+#endif /* CONFIG_PARAVIRT */
+
 /*
  * Set IOPL bits in EFLAGS from given mask
  */
-static inline void set_iopl_mask(unsigned mask)
+static fastcall inline void native_set_iopl_mask(unsigned mask)
 {
 	unsigned int reg;
 	__asm__ __volatile__ ("pushfl;"