diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index ac2405ed504d..f6eb01d8923a 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/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;
diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
index 54202b1805da..a00961d42e75 100644
--- a/arch/x86/kernel/vsmp_64.c
+++ b/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 */
diff --git a/include/asm-x86/apic.h b/include/asm-x86/apic.h
index bcfc07fd3661..f0321a427e16 100644
--- a/include/asm-x86/apic.h
+++ b/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)