x86, vsmp: Remove is_vsmp_box() from apic_is_clustered_box()

When a vSMP Foundation box is detected, the function apic_cluster_num() counts
the number of APIC clusters found. If more than one found, a multi board
configuration is assumed, and TSC marked as unstable. This behavior is
incorrect as vSMP Foundation may use processors from single node only, attached
to memory of other nodes - and such node may have more than one APIC cluster
(typically any recent intel box has more than single APIC_CLUSTERID(x)).

To fix this, we simply remove the code which detects a vSMP Foundation box and
affects apic_is_clusted_box() return value. This can be done because later the
kernel checks by itself if the TSC is stable using the
check_tsc_sync_[source|target]() functions and marks TSC as unstable if needed.

Acked-by: Shai Fultheim <shai@scalemp.com>
Signed-off-by: Oren Twaig <oren@scalemp.com>
Link: http://lkml.kernel.org/r/1404036068-11674-1-git-send-email-oren@scalemp.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 69ed79a..b40ea7e 100644 (file)
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -85,14 +85,6 @@ static inline bool apic_from_smp_config(void)
 #include <asm/paravirt.h>
 #endif
 
-#ifdef CONFIG_X86_64
-extern int is_vsmp_box(void);
-#else
-static inline int is_vsmp_box(void)
-{
-       return 0;
-}
-#endif
 extern int setup_profiling_timer(unsigned int);
 
 static inline void native_apic_mem_write(u32 reg, u32 v)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ca1bd75..6b35d30 100644 (file)
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2451,51 +2451,6 @@ static void apic_pm_activate(void) { }
 
 #ifdef CONFIG_X86_64
 
-static int apic_cluster_num(void)
-{
-       int i, clusters, zeros;
-       unsigned id;
-       u16 *bios_cpu_apicid;
-       DECLARE_BITMAP(clustermap, NUM_APIC_CLUSTERS);
-
-       bios_cpu_apicid = early_per_cpu_ptr(x86_bios_cpu_apicid);
-       bitmap_zero(clustermap, NUM_APIC_CLUSTERS);
-
-       for (i = 0; i < nr_cpu_ids; i++) {
-               /* are we being called early in kernel startup? */
-               if (bios_cpu_apicid) {
-                       id = bios_cpu_apicid[i];
-               } else if (i < nr_cpu_ids) {
-                       if (cpu_present(i))
-                               id = per_cpu(x86_bios_cpu_apicid, i);
-                       else
-                               continue;
-               } else
-                       break;
-
-               if (id != BAD_APICID)
-                       __set_bit(APIC_CLUSTERID(id), clustermap);
-       }
-
-       /* Problem:  Partially populated chassis may not have CPUs in some of
-        * the APIC clusters they have been allocated.  Only present CPUs have
-        * x86_bios_cpu_apicid entries, thus causing zeroes in the bitmap.
-        * Since clusters are allocated sequentially, count zeros only if
-        * they are bounded by ones.
-        */
-       clusters = 0;
-       zeros = 0;
-       for (i = 0; i < NUM_APIC_CLUSTERS; i++) {
-               if (test_bit(i, clustermap)) {
-                       clusters += 1 + zeros;
-                       zeros = 0;
-               } else
-                       ++zeros;
-       }
-
-       return clusters;
-}
-
 static int multi_checked;
 static int multi;
 
@@ -2540,20 +2495,7 @@ static void dmi_check_multi(void)
 int apic_is_clustered_box(void)
 {
        dmi_check_multi();
-       if (multi)
-               return 1;
-
-       if (!is_vsmp_box())
-               return 0;
-
-       /*
-        * ScaleMP vSMPowered boxes have one cluster per board and TSCs are
-        * not guaranteed to be synced between boards
-        */
-       if (apic_cluster_num() > 1)
-               return 1;
-
-       return 0;
+       return multi;
 }
 #endif