[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
--- a/arch/x86_64/kernel/genapic.c
+++ b/arch/x86_64/kernel/genapic.c
@@ -31,6 +31,7 @@
extern struct genapic apic_cluster;
extern struct genapic apic_flat;
+extern struct genapic apic_physflat;
struct genapic *genapic = &apic_flat;
@@ -44,12 +45,7 @@
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 @@
#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
--- 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 @@
.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,
+};