[POWERPC] Fix interrupt distribution in ppc970

In some of the PPC970 based systems, interrupt would be distributed to
offline cpus also even when booted with "maxcpus=1".  So check whether
cpu online map and cpu present map are equal or not.  If they are equal
default_distrib_server is used as interrupt server otherwise boot cpu
(default_server) used as interrupt server.

In addition to this, if an interrupt is assigned to a specific cpu (ie
smp affinity) and if that cpu is not online, the earlier code used to
return the default_distrib_server as interrupt server.  This
introduces an additional parameter to the get_irq function, called
strict_check.  Based on this parameter, if the cpu is not online
either default_distrib_server or -1 is returned.

Signed-off-by: Mohan Kumar M <mohan@in.ibm.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 29 insertions, 24 deletions

diff --git a/arch/powerpc/platforms/pseries/xics.c b/arch/powerpc/platforms/pseries/xics.c
index f1df942072bb..5bd90a7eb763 100644
--- a/arch/powerpc/platforms/pseries/xics.c
+++ b/arch/powerpc/platforms/pseries/xics.c
@@ -156,9 +156,9 @@ static inline void lpar_qirr_info(int n_cpu , u8 value)
 
 
 #ifdef CONFIG_SMP
-static int get_irq_server(unsigned int virq)
+static int get_irq_server(unsigned int virq, unsigned int strict_check)
 {
-        unsigned int server;
+        int server;
         /* For the moment only implement delivery to all cpus or one cpu */
         cpumask_t cpumask = irq_desc[virq].affinity;
         cpumask_t tmp = CPU_MASK_NONE;
@@ -166,22 +166,25 @@ static int get_irq_server(unsigned int virq)
         if (!distribute_irqs)
                 return default_server;
 
-        if (cpus_equal(cpumask, CPU_MASK_ALL)) {
-                server = default_distrib_server;
-        } else {
+        if (!cpus_equal(cpumask, CPU_MASK_ALL)) {
                 cpus_and(tmp, cpu_online_map, cpumask);
 
-                if (cpus_empty(tmp))
-                        server = default_distrib_server;
-                else
-                        server = get_hard_smp_processor_id(first_cpu(tmp));
+                server = first_cpu(tmp);
+
+                if (server < NR_CPUS)
+                        return get_hard_smp_processor_id(server);
+
+                if (strict_check)
+                        return -1;
         }
 
-        return server;
+        if (cpus_equal(cpu_online_map, cpu_present_map))
+                return default_distrib_server;
 
+        return default_server;
 }
 #else
-static int get_irq_server(unsigned int virq)
+static int get_irq_server(unsigned int virq, unsigned int strict_check)
 {
         return default_server;
 }
@@ -192,7 +195,7 @@ static void xics_unmask_irq(unsigned int virq)
 {
         unsigned int irq;
         int call_status;
-        unsigned int server;
+        int server;
 
         pr_debug("xics: unmask virq %d\n", virq);
 
@@ -201,7 +204,7 @@ static void xics_unmask_irq(unsigned int virq)
         if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
                 return;
 
-        server = get_irq_server(virq);
+        server = get_irq_server(virq, 0);
 
         call_status = rtas_call(ibm_set_xive, 3, 1, NULL, irq, server,
                                 DEFAULT_PRIORITY);
@@ -398,8 +401,7 @@ static void xics_set_affinity(unsigned int virq, cpumask_t cpumask)
         unsigned int irq;
         int status;
         int xics_status[2];
-        unsigned long newmask;
-        cpumask_t tmp = CPU_MASK_NONE;
+        int irq_server;
 
         irq = (unsigned int)irq_map[virq].hwirq;
         if (irq == XICS_IPI || irq == XICS_IRQ_SPURIOUS)
@@ -413,18 +415,21 @@ static void xics_set_affinity(unsigned int virq, cpumask_t cpumask)
                 return;
         }
 
-        /* For the moment only implement delivery to all cpus or one cpu */
-        if (cpus_equal(cpumask, CPU_MASK_ALL)) {
-                newmask = default_distrib_server;
-        } else {
-                cpus_and(tmp, cpu_online_map, cpumask);
-                if (cpus_empty(tmp))
-                        return;
-                newmask = get_hard_smp_processor_id(first_cpu(tmp));
+        /*
+         * For the moment only implement delivery to all cpus or one cpu.
+         * Get current irq_server for the given irq
+         */
+        irq_server = get_irq_server(irq, 1);
+        if (irq_server == -1) {
+                char cpulist[128];
+                cpumask_scnprintf(cpulist, sizeof(cpulist), cpumask);
+                printk(KERN_WARNING "xics_set_affinity: No online cpus in "
+                                "the mask %s for irq %d\n", cpulist, virq);
+                return;
         }
 
         status = rtas_call(ibm_set_xive, 3, 1, NULL,
-                                irq, newmask, xics_status[1]);
+                                irq, irq_server, xics_status[1]);
 
         if (status) {
                 printk(KERN_ERR "xics_set_affinity: irq=%u ibm,set-xive "