x64, x2apic/intr-remap: support for x2apic physical mode support

x2apic Physical mode  support. By default we will use x2apic cluster mode.
x2apic physical mode can be selected using "x2apic_phys" boot parameter.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: akpm@linux-foundation.org
Cc: arjan@linux.intel.com
Cc: andi@firstfloor.org
Cc: ebiederm@xmission.com
Cc: jbarnes@virtuousgeek.org
Cc: steiner@sgi.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 15 insertions, 3 deletions

diff --git a/arch/x86/kernel/genapic_64.c b/arch/x86/kernel/genapic_64.c
index 792e21ba1a81..3940d8161f8b 100644
--- a/arch/x86/kernel/genapic_64.c
+++ b/arch/x86/kernel/genapic_64.c
@@ -30,6 +30,15 @@ DEFINE_PER_CPU(int, x2apic_extra_bits);
 
 struct genapic __read_mostly *genapic = &apic_flat;
 
+static int x2apic_phys = 0;
+
+static int set_x2apic_phys_mode(char *arg)
+{
+        x2apic_phys = 1;
+        return 0;
+}
+early_param("x2apic_phys", set_x2apic_phys_mode);
+
 static enum uv_system_type uv_system_type;
 
 /*
@@ -39,9 +48,12 @@ void __init setup_apic_routing(void)
 {
         if (uv_system_type == UV_NON_UNIQUE_APIC)
                 genapic = &apic_x2apic_uv_x;
-        else if (cpu_has_x2apic && intr_remapping_enabled)
-                genapic = &apic_x2apic_cluster;
-        else
+        else if (cpu_has_x2apic && intr_remapping_enabled) {
+                if (x2apic_phys)
+                        genapic = &apic_x2apic_phys;
+                else
+                        genapic = &apic_x2apic_cluster;
+        } else
 #ifdef CONFIG_ACPI
         /*
          * Quirk: some x86_64 machines can only use physical APIC mode