x86: apic_is_clustered_box for vsmp

quad core 8 socket system will have apic id lifting.the apic id range could
be [4, 0x23]. and apic_is_clustered_box will think that need to three clusters
and that is larger than 2. So it is treated as a clustered_box.

and will get:

   Marking TSC unstable due to TSCs unsynchronized

even if the CPUs have X86_FEATURE_CONSTANT_TSC set.

this quick fix will check if the cpu is from AMD.

but vsmp still needs that checking...

this patch is fix to make sure that vsmp not to be passed.
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/apic_64.c

@@ -1182,9 +1182,9 @@ __cpuinit int apic_is_clustered_box(void)
 	 * there is not this kind of box with AMD CPU yet.
 	 * Some AMD box with quadcore cpu and 8 sockets apicid
 	 * will be [4, 0x23] or [8, 0x27] could be thought to
-	 * have three apic_clusters. So go out early.
+	 * vsmp box still need checking...
 	 */
-	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
+	if (!is_vsmp_box() && (boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
 		return 0;
 
 	bios_cpu_apicid = x86_bios_cpu_apicid_early_ptr;

arch/x86/kernel/vsmp_64.c

@@ -72,19 +72,34 @@ static unsigned __init vsmp_patch(u8 type, u16 clobbers, void *ibuf,
 
 }
 
+static int vsmp = -1;
+
+int is_vsmp_box(void)
+{
+	if (vsmp != -1)
+		return vsmp;
+
+	vsmp = 0;
+	if (!early_pci_allowed())
+		return vsmp;
+
+	/* Check if we are running on a ScaleMP vSMP box */
+	if (read_pci_config(0, 0x1f, 0, PCI_VENDOR_ID) ==
+	     (PCI_VENDOR_ID_SCALEMP || (PCI_DEVICE_ID_SCALEMP_VSMP_CTL << 16)))
+		vsmp = 1;
+
+	return vsmp;
+}
+
 void __init vsmp_init(void)
 {
 	void *address;
 	unsigned int cap, ctl, cfg;
 
-	if (!early_pci_allowed())
+	if (!is_vsmp_box())
 		return;
 
-	/* Check if we are running on a ScaleMP vSMP box */
-	if ((read_pci_config_16(0, 0x1f, 0, PCI_VENDOR_ID) !=
-	     PCI_VENDOR_ID_SCALEMP) ||
-	    (read_pci_config_16(0, 0x1f, 0, PCI_DEVICE_ID) !=
-	     PCI_DEVICE_ID_SCALEMP_VSMP_CTL))
+	if (!early_pci_allowed())
 		return;
 
 	/* If we are, use the distinguished irq functions */

include/asm-x86/apic.h

@@ -51,12 +51,17 @@ extern unsigned boot_cpu_id;
  */
 #ifdef CONFIG_PARAVIRT
 #include <asm/paravirt.h>
+extern int is_vsmp_box(void);
 #else
 #define apic_write native_apic_write
 #define apic_write_atomic native_apic_write_atomic
 #define apic_read native_apic_read
 #define setup_boot_clock setup_boot_APIC_clock
 #define setup_secondary_clock setup_secondary_APIC_clock
+static int inline is_vsmp_box(void)
+{
+	return 0;
+}
 #endif
 
 static inline void native_apic_write(unsigned long reg, u32 v)