x86: clean up vSMP detection

vSMP detection: access pci config space early in boot to detect if the
system is a vSMPowered box, and cache the result in a flag, so that
is_vsmp_box() retrieves the value of the flag always.

Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 19 insertions, 9 deletions

diff --git a/arch/x86/kernel/vsmp_64.c b/arch/x86/kernel/vsmp_64.c
index 1e9a791dbe39..caf2a26f5cfd 100644
--- a/arch/x86/kernel/vsmp_64.c
+++ b/arch/x86/kernel/vsmp_64.c
@@ -108,25 +108,34 @@ static void __init set_vsmp_pv_ops(void)
 #endif
 
 #ifdef CONFIG_PCI
-static int vsmp = -1;
+static int is_vsmp = -1;
 
-int is_vsmp_box(void)
+static void __init detect_vsmp_box(void)
 {
-        if (vsmp != -1)
-                return vsmp;
+        is_vsmp = 0;
 
-        vsmp = 0;
         if (!early_pci_allowed())
-                return vsmp;
+                return;
 
-        /* Check if we are running on a ScaleMP vSMP box */
+        /* Check if we are running on a ScaleMP vSMPowered box */
         if (read_pci_config(0, 0x1f, 0, PCI_VENDOR_ID) ==
              (PCI_VENDOR_ID_SCALEMP | (PCI_DEVICE_ID_SCALEMP_VSMP_CTL << 16)))
-                vsmp = 1;
+                is_vsmp = 1;
+}
 
-        return vsmp;
+int is_vsmp_box(void)
+{
+        if (is_vsmp != -1)
+                return is_vsmp;
+        else {
+                WARN_ON_ONCE(1);
+                return 0;
+        }
 }
 #else
+static int __init detect_vsmp_box(void)
+{
+}
 int is_vsmp_box(void)
 {
         return 0;
@@ -135,6 +144,7 @@ int is_vsmp_box(void)
 
 void __init vsmp_init(void)
 {
+        detect_vsmp_box();
         if (!is_vsmp_box())
                 return;