[PATCH] x86_64: Support more than 8 cores on AMD systems

Use physical mode instead of logical mode to address more CPUs.  This is also
used in the CPU hotplug case to avoid a race.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/x86_64/kernel/genapic.c b/arch/x86_64/kernel/genapic.c
index 69b9c25..30c843a 100644 (file)
--- a/arch/x86_64/kernel/genapic.c
+++ b/arch/x86_64/kernel/genapic.c
@@ -31,6 +31,7 @@ u8 x86_cpu_to_log_apicid[NR_CPUS] = { [0 ... NR_CPUS-1] = BAD_APICID };
 
 extern struct genapic apic_cluster;
 extern struct genapic apic_flat;
+extern struct genapic apic_physflat;
 
 struct genapic *genapic = &apic_flat;
 
@@ -44,12 +45,7 @@ void __init clustered_apic_check(void)
        u8 clusters, max_cluster;
        u8 id;
        u8 cluster_cnt[NUM_APIC_CLUSTERS];
-
-       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
-               /* AMD always uses flat mode right now */
-               genapic = &apic_flat;
-               goto print;
-       }
+       int num_cpus = 0;
 
 #if defined(CONFIG_ACPI_BUS)
        /*
@@ -64,15 +60,34 @@ void __init clustered_apic_check(void)
 #endif
 
        memset(cluster_cnt, 0, sizeof(cluster_cnt));
-
        for (i = 0; i < NR_CPUS; i++) {
                id = bios_cpu_apicid[i];
-               if (id != BAD_APICID)
-                       cluster_cnt[APIC_CLUSTERID(id)]++;
+               if (id == BAD_APICID)
+                       continue;
+               num_cpus++;
+               cluster_cnt[APIC_CLUSTERID(id)]++;
        }
 
+       /* Don't use clustered mode on AMD platforms. */
+       if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+               genapic = &apic_physflat;
+#ifndef CONFIG_CPU_HOTPLUG
+               /* In the CPU hotplug case we cannot use broadcast mode
+                  because that opens a race when a CPU is removed.
+                  Stay at physflat mode in this case.
+                  It is bad to do this unconditionally though. Once
+                  we have ACPI platform support for CPU hotplug
+                  we should detect hotplug capablity from ACPI tables and
+                  only do this when really needed. -AK */
+               if (num_cpus <= 8)
+                       genapic = &apic_flat;
+#endif
+               goto print;
+       }
+
        clusters = 0;
        max_cluster = 0;
+
        for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
                if (cluster_cnt[i] > 0) {
                        ++clusters;

diff --git a/arch/x86_64/kernel/genapic_flat.c b/arch/x86_64/kernel/genapic_flat.c
index fdfa15f..adc9628 100644 (file)
--- a/arch/x86_64/kernel/genapic_flat.c
+++ b/arch/x86_64/kernel/genapic_flat.c
@@ -2,7 +2,7 @@
  * Copyright 2004 James Cleverdon, IBM.
  * Subject to the GNU Public License, v.2
  *
- * Flat APIC subarch code.  Maximum 8 CPUs, logical delivery.
+ * Flat APIC subarch code.
  *
  * Hacked for x86-64 by James Cleverdon from i386 architecture code by
  * Martin Bligh, Andi Kleen, James Bottomley, John Stultz, and
@@ -119,3 +119,63 @@ struct genapic apic_flat =  {
        .cpu_mask_to_apicid = flat_cpu_mask_to_apicid,
        .phys_pkg_id = phys_pkg_id,
 };
+
+/*
+ * Physflat mode is used when there are more than 8 CPUs on a AMD system.
+ * We cannot use logical delivery in this case because the mask
+ * overflows, so use physical mode.
+ */
+
+static cpumask_t physflat_target_cpus(void)
+{
+       return cpumask_of_cpu(0);
+}
+
+static void physflat_send_IPI_mask(cpumask_t cpumask, int vector)
+{
+       send_IPI_mask_sequence(cpumask, vector);
+}
+
+static void physflat_send_IPI_allbutself(int vector)
+{
+       cpumask_t allbutme = cpu_online_map;
+       int me = get_cpu();
+       cpu_clear(me, allbutme);
+       physflat_send_IPI_mask(allbutme, vector);
+       put_cpu();
+}
+
+static void physflat_send_IPI_all(int vector)
+{
+       physflat_send_IPI_mask(cpu_online_map, vector);
+}
+
+static unsigned int physflat_cpu_mask_to_apicid(cpumask_t cpumask)
+{
+       int cpu;
+
+       /*
+        * We're using fixed IRQ delivery, can only return one phys APIC ID.
+        * May as well be the first.
+        */
+       cpu = first_cpu(cpumask);
+       if ((unsigned)cpu < NR_CPUS)
+               return x86_cpu_to_apicid[cpu];
+       else
+               return BAD_APICID;
+}
+
+struct genapic apic_physflat =  {
+       .name = "physical flat",
+       .int_delivery_mode = dest_LowestPrio,
+       .int_dest_mode = (APIC_DEST_PHYSICAL != 0),
+       .int_delivery_dest = APIC_DEST_PHYSICAL | APIC_DM_LOWEST,
+       .target_cpus = physflat_target_cpus,
+       .apic_id_registered = flat_apic_id_registered,
+       .init_apic_ldr = flat_init_apic_ldr,/*not needed, but shouldn't hurt*/
+       .send_IPI_all = physflat_send_IPI_all,
+       .send_IPI_allbutself = physflat_send_IPI_allbutself,
+       .send_IPI_mask = physflat_send_IPI_mask,
+       .cpu_mask_to_apicid = physflat_cpu_mask_to_apicid,
+       .phys_pkg_id = phys_pkg_id,
+};