[IA64] support for cpu0 removal

here is the BSP removal support for IA64. Its pretty much the same thing that
was released a while back, but has your feedback incorporated.

- Removed CONFIG_BSP_REMOVE_WORKAROUND and associated cmdline param
- Fixed compile issue with sn2/zx1 due to a undefined fix_b0_for_bsp
- some formatting nits (whitespace etc)

This has been tested on tiger and long back by alex on hp systems as well.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 108 insertions, 6 deletions

diff --git a/arch/ia64/kernel/smpboot.c b/arch/ia64/kernel/smpboot.c
index 8f44e7d2df66..e9d37bf67d69 100644
--- a/arch/ia64/kernel/smpboot.c
+++ b/arch/ia64/kernel/smpboot.c
@@ -70,6 +70,12 @@
 #endif
 
 #ifdef CONFIG_HOTPLUG_CPU
+#ifdef CONFIG_PERMIT_BSP_REMOVE
+#define bsp_remove_ok   1
+#else
+#define bsp_remove_ok   0
+#endif
+
 /*
  * Store all idle threads, this can be reused instead of creating
  * a new thread. Also avoids complicated thread destroy functionality
@@ -104,7 +110,7 @@ struct sal_to_os_boot *sal_state_for_booting_cpu = &sal_boot_rendez_state[0];
 /*
  * ITC synchronization related stuff:
  */
-#define MASTER  0
+#define MASTER  (0)
 #define SLAVE   (SMP_CACHE_BYTES/8)
 
 #define NUM_ROUNDS      64      /* magic value */
@@ -151,6 +157,27 @@ char __initdata no_int_routing;
 
 unsigned char smp_int_redirect; /* are INT and IPI redirectable by the chipset? */
 
+#ifdef CONFIG_FORCE_CPEI_RETARGET
+#define CPEI_OVERRIDE_DEFAULT   (1)
+#else
+#define CPEI_OVERRIDE_DEFAULT   (0)
+#endif
+
+unsigned int force_cpei_retarget = CPEI_OVERRIDE_DEFAULT;
+
+static int __init
+cmdl_force_cpei(char *str)
+{
+        int value=0;
+
+        get_option (&str, &value);
+        force_cpei_retarget = value;
+
+        return 1;
+}
+
+__setup("force_cpei=", cmdl_force_cpei);
+
 static int __init
 nointroute (char *str)
 {
@@ -161,6 +188,27 @@ nointroute (char *str)
 
 __setup("nointroute", nointroute);
 
+static void fix_b0_for_bsp(void)
+{
+#ifdef CONFIG_HOTPLUG_CPU
+        int cpuid;
+        static int fix_bsp_b0 = 1;
+
+        cpuid = smp_processor_id();
+
+        /*
+         * Cache the b0 value on the first AP that comes up
+         */
+        if (!(fix_bsp_b0 && cpuid))
+                return;
+
+        sal_boot_rendez_state[0].br[0] = sal_boot_rendez_state[cpuid].br[0];
+        printk ("Fixed BSP b0 value from CPU %d\n", cpuid);
+
+        fix_bsp_b0 = 0;
+#endif
+}
+
 void
 sync_master (void *arg)
 {
@@ -327,8 +375,9 @@ smp_setup_percpu_timer (void)
 static void __devinit
 smp_callin (void)
 {
-        int cpuid, phys_id;
+        int cpuid, phys_id, itc_master;
         extern void ia64_init_itm(void);
+        extern volatile int time_keeper_id;
 
 #ifdef CONFIG_PERFMON
         extern void pfm_init_percpu(void);
@@ -336,6 +385,7 @@ smp_callin (void)
 
         cpuid = smp_processor_id();
         phys_id = hard_smp_processor_id();
+        itc_master = time_keeper_id;
 
         if (cpu_online(cpuid)) {
                 printk(KERN_ERR "huh, phys CPU#0x%x, CPU#0x%x already present??\n",
@@ -343,6 +393,8 @@ smp_callin (void)
                 BUG();
         }
 
+        fix_b0_for_bsp();
+
         lock_ipi_calllock();
         cpu_set(cpuid, cpu_online_map);
         unlock_ipi_calllock();
@@ -365,8 +417,8 @@ smp_callin (void)
                  * calls spin_unlock_bh(), which calls spin_unlock_bh(), which calls
                  * local_bh_enable(), which bugs out if irqs are not enabled...
                  */
-                Dprintk("Going to syncup ITC with BP.\n");
-                ia64_sync_itc(0);
+                Dprintk("Going to syncup ITC with ITC Master.\n");
+                ia64_sync_itc(itc_master);
         }
 
         /*
@@ -638,6 +690,47 @@ remove_siblinginfo(int cpu)
 }
 
 extern void fixup_irqs(void);
+
+int migrate_platform_irqs(unsigned int cpu)
+{
+        int new_cpei_cpu;
+        irq_desc_t *desc = NULL;
+        cpumask_t       mask;
+        int             retval = 0;
+
+        /*
+         * dont permit CPEI target to removed.
+         */
+        if (cpe_vector > 0 && is_cpu_cpei_target(cpu)) {
+                printk ("CPU (%d) is CPEI Target\n", cpu);
+                if (can_cpei_retarget()) {
+                        /*
+                         * Now re-target the CPEI to a different processor
+                         */
+                        new_cpei_cpu = any_online_cpu(cpu_online_map);
+                        mask = cpumask_of_cpu(new_cpei_cpu);
+                        set_cpei_target_cpu(new_cpei_cpu);
+                        desc = irq_descp(ia64_cpe_irq);
+                        /*
+                         * Switch for now, immediatly, we need to do fake intr
+                         * as other interrupts, but need to study CPEI behaviour with
+                         * polling before making changes.
+                         */
+                        if (desc) {
+                                desc->handler->disable(ia64_cpe_irq);
+                                desc->handler->set_affinity(ia64_cpe_irq, mask);
+                                desc->handler->enable(ia64_cpe_irq);
+                                printk ("Re-targetting CPEI to cpu %d\n", new_cpei_cpu);
+                        }
+                }
+                if (!desc) {
+                        printk ("Unable to retarget CPEI, offline cpu [%d] failed\n", cpu);
+                        retval = -EBUSY;
+                }
+        }
+        return retval;
+}
+
 /* must be called with cpucontrol mutex held */
 int __cpu_disable(void)
 {
@@ -646,8 +739,17 @@ int __cpu_disable(void)
         /*
          * dont permit boot processor for now
          */
-        if (cpu == 0)
-                return -EBUSY;
+        if (cpu == 0 && !bsp_remove_ok) {
+                printk ("Your platform does not support removal of BSP\n");
+                return (-EBUSY);
+        }
+
+        cpu_clear(cpu, cpu_online_map);
+
+        if (migrate_platform_irqs(cpu)) {
+                cpu_set(cpu, cpu_online_map);
+                return (-EBUSY);
+        }
 
         remove_siblinginfo(cpu);
         cpu_clear(cpu, cpu_online_map);