[PATCH] i386: Add smp_ops interface

Add a smp_ops interface. This abstracts the API defined by
<linux/smp.h> for use within arch/i386. The primary intent is that it
be used by a paravirtualizing hypervisor to implement SMP, but it
could also be used by non-APIC-using sub-architectures.

This is related to CONFIG_PARAVIRT, but is implemented unconditionally
since it is simpler that way and not a highly performance-sensitive
interface.

Signed-off-by: Jeremy Fitzhardinge <[e-mail]>
Signed-off-by: Andi Kleen <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: James Bottomley <[e-mail]>

arch/i386/kernel/smp.c

···
  * it goes straight through and wastes no time serializing
  * anything. Worst case is that we lose a reschedule ...
  */
-void smp_send_reschedule(int cpu)
+void native_smp_send_reschedule(int cpu)
 {
 	WARN_ON(cpu_is_offline(cpu));
 	send_IPI_mask(cpumask_of_cpu(cpu), RESCHEDULE_VECTOR);
···
  * You must not call this function with disabled interrupts or from a
  * hardware interrupt handler or from a bottom half handler.
  */
-int smp_call_function_mask(cpumask_t mask,
-			   void (*func)(void *), void *info,
-			   int wait)
+int native_smp_call_function_mask(cpumask_t mask,
+				  void (*func)(void *), void *info,
+				  int wait)
 {
 	struct call_data_struct data;
 	cpumask_t allbutself;
···
  * this function calls the 'stop' function on all other CPUs in the system.
  */
 
-void smp_send_stop(void)
+void native_smp_send_stop(void)
 {
 	/* Don't deadlock on the call lock in panic */
 	int nolock = !spin_trylock(&call_lock);
···
 
 	return cpuid >= 0 ? cpuid : 0;
 }
+
+struct smp_ops smp_ops = {
+	.smp_prepare_boot_cpu = native_smp_prepare_boot_cpu,
+	.smp_prepare_cpus = native_smp_prepare_cpus,
+	.cpu_up = native_cpu_up,
+	.smp_cpus_done = native_smp_cpus_done,
+
+	.smp_send_stop = native_smp_send_stop,
+	.smp_send_reschedule = native_smp_send_reschedule,
+	.smp_call_function_mask = native_smp_call_function_mask,
+};

arch/i386/kernel/smpboot.c

···
 
 /* These are wrappers to interface to the new boot process.  Someone
    who understands all this stuff should rewrite it properly. --RR 15/Jul/02 */
-void __init smp_prepare_cpus(unsigned int max_cpus)
+void __init native_smp_prepare_cpus(unsigned int max_cpus)
 {
 	smp_commenced_mask = cpumask_of_cpu(0);
 	cpu_callin_map = cpumask_of_cpu(0);
···
 	asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_PDA) : "memory");
 }
 
-void __init smp_prepare_boot_cpu(void)
+void __init native_smp_prepare_boot_cpu(void)
 {
 	unsigned int cpu = smp_processor_id();
 
···
 }
 #endif /* CONFIG_HOTPLUG_CPU */
 
-int __cpuinit __cpu_up(unsigned int cpu)
+int __cpuinit native_cpu_up(unsigned int cpu)
 {
 	unsigned long flags;
 #ifdef CONFIG_HOTPLUG_CPU
···
 	return 0;
 }
 
-void __init smp_cpus_done(unsigned int max_cpus)
+void __init native_smp_cpus_done(unsigned int max_cpus)
 {
 #ifdef CONFIG_X86_IO_APIC
 	setup_ioapic_dest();

include/asm-i386/smp.h

···
 extern void cpu_uninit(void);
 #endif
 
+struct smp_ops
+{
+	void (*smp_prepare_boot_cpu)(void);
+	void (*smp_prepare_cpus)(unsigned max_cpus);
+	int (*cpu_up)(unsigned cpu);
+	void (*smp_cpus_done)(unsigned max_cpus);
+
+	void (*smp_send_stop)(void);
+	void (*smp_send_reschedule)(int cpu);
+	int (*smp_call_function_mask)(cpumask_t mask,
+				      void (*func)(void *info), void *info,
+				      int wait);
+};
+
+extern struct smp_ops smp_ops;
+
+static inline void smp_prepare_boot_cpu(void)
+{
+	smp_ops.smp_prepare_boot_cpu();
+}
+static inline void smp_prepare_cpus(unsigned int max_cpus)
+{
+	smp_ops.smp_prepare_cpus(max_cpus);
+}
+static inline int __cpu_up(unsigned int cpu)
+{
+	return smp_ops.cpu_up(cpu);
+}
+static inline void smp_cpus_done(unsigned int max_cpus)
+{
+	smp_ops.smp_cpus_done(max_cpus);
+}
+
+static inline void smp_send_stop(void)
+{
+	smp_ops.smp_send_stop();
+}
+static inline void smp_send_reschedule(int cpu)
+{
+	smp_ops.smp_send_reschedule(cpu);
+}
+static inline int smp_call_function_mask(cpumask_t mask,
+					 void (*func) (void *info), void *info,
+					 int wait)
+{
+	return smp_ops.smp_call_function_mask(mask, func, info, wait);
+}
+
+void native_smp_prepare_boot_cpu(void);
+void native_smp_prepare_cpus(unsigned int max_cpus);
+int native_cpu_up(unsigned int cpunum);
+void native_smp_cpus_done(unsigned int max_cpus);
+
 #ifndef CONFIG_PARAVIRT
 #define startup_ipi_hook(phys_apicid, start_eip, start_esp) 		\
 do { } while (0)