3 files changed, 12 insertions, 1 deletions

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 42f2f8377422..9b2c04910e0d 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -410,7 +410,7 @@ static inline unsigned default_get_apic_id(unsigned long x)
 {
         unsigned int ver = GET_APIC_VERSION(apic_read(APIC_LVR));
 
-        if (APIC_XAPIC(ver))
+        if (APIC_XAPIC(ver) || boot_cpu_has(X86_FEATURE_EXTD_APICID))
                 return (x >> 24) & 0xFF;
         else
                 return (x >> 24) & 0x0F;
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index bb83b1c397aa..78dee4f0f7aa 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -94,6 +94,7 @@
 #define X86_FEATURE_TSC_RELIABLE (3*32+23) /* TSC is known to be reliable */
 #define X86_FEATURE_NONSTOP_TSC (3*32+24) /* TSC does not stop in C states */
 #define X86_FEATURE_CLFLUSH_MONITOR (3*32+25) /* "" clflush reqd with monitor */
+#define X86_FEATURE_EXTD_APICID (3*32+26) /* has extended APICID (8 bits) */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3        (4*32+ 0) /* "pni" SSE-3 */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 7e4a459daa64..0802e151c2c9 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -6,6 +6,7 @@
 #include <asm/processor.h>
 #include <asm/apic.h>
 #include <asm/cpu.h>
+#include <asm/pci-direct.h>
 
 #ifdef CONFIG_X86_64
 # include <asm/numa_64.h>
@@ -351,6 +352,15 @@ static void __cpuinit early_init_amd(struct cpuinfo_x86 *c)
                     (c->x86_model == 8 && c->x86_mask >= 8))
                         set_cpu_cap(c, X86_FEATURE_K6_MTRR);
 #endif
+#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PCI)
+        /* check CPU config space for extended APIC ID */
+        if (c->x86 >= 0xf) {
+                unsigned int val;
+                val = read_pci_config(0, 24, 0, 0x68);
+                if ((val & ((1 << 17) | (1 << 18))) == ((1 << 17) | (1 << 18)))
+                        set_cpu_cap(c, X86_FEATURE_EXTD_APICID);
+        }
+#endif
 }
 
 static void __cpuinit init_amd(struct cpuinfo_x86 *c)