[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>

1 files changed, 61 insertions, 1 deletions

diff --git a/arch/x86_64/kernel/genapic_flat.c b/arch/x86_64/kernel/genapic_flat.c
index fdfa15f5d2ed..adc96282a9e2 100644
--- 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,
+};