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>

2 files changed, 1 insertions, 67 deletions

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 69ed79aa9085..b40ea7e4bae9 100644
--- 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 ca1bd75e3de2..6b35d308688c 100644
--- 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