New SMP IPI interface function called on_selected_cpus(), currently implemented

only for x86. The x86 implementation of smp_call_function has been simplified 
and is now based on on_slected_cpus().

Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Keir Fraser <keir@xensource.com>

xen/arch/x86/smp.c

@@ -266,7 +266,7 @@ void smp_send_event_check_mask(cpumask_t mask)
 }
 
 /*
- * Structure and data for smp_call_function().
+ * Structure and data for smp_call_function()/on_selected_cpus().
  */
 
 struct call_data_struct {
@@ -275,41 +275,48 @@ struct call_data_struct {
     int wait;
     atomic_t started;
     atomic_t finished;
+    cpumask_t selected;
 };
 
-static spinlock_t call_lock = SPIN_LOCK_UNLOCKED;
+static DEFINE_SPINLOCK(call_lock);
 static struct call_data_struct *call_data;
 
-/*
- * Run a function on all other CPUs.
- *  @func: The function to run. This must be fast and non-blocking.
- *  @info: An arbitrary pointer to pass to the function.
- *  @wait: If true, spin until function has completed on other CPUs.
- *  Returns: 0 on success, else a negative status code.
- */
 int smp_call_function(
-    void (*func) (void *info), void *info, int unused, int wait)
+    void (*func) (void *info),
+    void *info,
+    int retry,
+    int wait)
+{
+    cpumask_t allbutself = cpu_online_map;
+    cpu_clear(smp_processor_id(), allbutself);
+    return on_selected_cpus(allbutself, func, info, retry, wait);
+}
+
+extern int on_selected_cpus(
+    cpumask_t selected,
+    void (*func) (void *info),
+    void *info,
+    int retry,
+    int wait)
 {
     struct call_data_struct data;
-    unsigned int nr_cpus = num_online_cpus() - 1;
+    unsigned int nr_cpus = cpus_weight(selected);
 
     ASSERT(local_irq_is_enabled());
 
-    if ( nr_cpus == 0 )
-        return 0;
-
     data.func = func;
     data.info = info;
     data.wait = wait;
     atomic_set(&data.started, 0);
     atomic_set(&data.finished, 0);
+    data.selected = selected;
 
     spin_lock(&call_lock);
 
     call_data = &data;
     wmb();
 
-    send_IPI_allbutself(CALL_FUNCTION_VECTOR);
+    send_IPI_mask(selected, CALL_FUNCTION_VECTOR);
 
     while ( atomic_read(wait ? &data.finished : &data.started) != nr_cpus )
         cpu_relax();
@@ -353,6 +360,9 @@ fastcall void smp_call_function_interrupt(struct cpu_user_regs *regs)
     ack_APIC_irq();
     perfc_incrc(ipis);
 
+    if ( !cpu_isset(smp_processor_id(), call_data->selected) )
+        return;
+
     if ( call_data->wait )
     {
         (*func)(info);

xen/include/xen/smp.h

@@ -45,33 +45,35 @@ extern void smp_cpus_done(unsigned int max_cpus);
  * Call a function on all other processors
  */
 extern int smp_call_function(
-    void (*func) (void *info), void *info, int retry, int wait);
+    void (*func) (void *info),
+    void *info,
+    int retry,
+    int wait);
+
+/* 
+ * Call a function on a selection of processors
+ */
+extern int on_selected_cpus(
+    cpumask_t selected,
+    void (*func) (void *info),
+    void *info,
+    int retry,
+    int wait);
 
 /*
  * Call a function on all processors
  */
-static inline int on_each_cpu(void (*func) (void *info), void *info,
-                              int retry, int wait)
+static inline int on_each_cpu(
+    void (*func) (void *info),
+    void *info,
+    int retry,
+    int wait)
 {
     int ret = smp_call_function(func, info, retry, wait);
     func(info);
     return ret;
 }
 
-extern volatile unsigned long smp_msg_data;
-extern volatile int smp_src_cpu;
-extern volatile int smp_msg_id;
-
-#define MSG_ALL_BUT_SELF	0x8000	/* Assume <32768 CPU's */
-#define MSG_ALL			0x8001
-
-#define MSG_INVALIDATE_TLB	0x0001	/* Remote processor TLB invalidate */
-#define MSG_STOP_CPU		0x0002	/* Sent to shut down slave CPU's
-					 * when rebooting
-					 */
-#define MSG_RESCHEDULE		0x0003	/* Reschedule request from master CPU*/
-#define MSG_CALL_FUNCTION       0x0004  /* Call function on all other CPUs */
-
 /*
  * Mark the boot cpu "online" so that it can call console drivers in
  * printk() and can access its per-cpu storage.
@@ -93,6 +95,18 @@ void smp_prepare_boot_cpu(void);
 #define num_booting_cpus()			1
 #define smp_prepare_boot_cpu()			do {} while (0)
 
+static inline int on_selected_cpus(
+    cpumask_t selected,
+    void (*func) (void *info),
+    void *info,
+    int retry,
+    int wait)
+{
+    if ( cpu_isset(0, selected) )
+        func(info);
+    return 0;
+}
+
 #endif
 
 #define smp_processor_id() raw_smp_processor_id()