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authorPavel Tatashin <pasha.tatashin@oracle.com>2017-10-27 20:11:00 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-11-15 15:53:20 +0100
commit9d5e5994c5f90121ac09efd04ee565aa8bddc049 (patch)
tree00704caef795f9c4dc9d7b75ae37dd24c502adc9
parent9313d039c4d00c0552fc03c63f5228f2dc6f452a (diff)
x86/smpboot: Make optimization of delay calibration work correctly
commit 76ce7cfe35ef58f34e6ba85327afb5fbf6c3ff9b upstream. If the TSC has constant frequency then the delay calibration can be skipped when it has been calibrated for a package already. This is checked in calibrate_delay_is_known(), but that function is buggy in two aspects: It returns 'false' if (!tsc_disabled && !cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC) which is obviously the reverse of the intended check and the check for the sibling mask cannot work either because the topology links have not been set up yet. Correct the condition and move the call to set_cpu_sibling_map() before invoking calibrate_delay() so the sibling check works correctly. [ tglx: Rewrote changelong ] Fixes: c25323c07345 ("x86/tsc: Use topology functions") Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: peterz@infradead.org Cc: bob.picco@oracle.com Cc: steven.sistare@oracle.com Cc: daniel.m.jordan@oracle.com Link: https://lkml.kernel.org/r/20171028001100.26603-1-pasha.tatashin@oracle.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/x86/kernel/smpboot.c11
-rw-r--r--arch/x86/kernel/tsc.c8
2 files changed, 9 insertions, 10 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 36171bcd91f8..9fe7b9e1ae30 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -181,6 +181,12 @@ static void smp_callin(void)
smp_store_cpu_info(cpuid);
/*
+ * The topology information must be up to date before
+ * calibrate_delay() and notify_cpu_starting().
+ */
+ set_cpu_sibling_map(raw_smp_processor_id());
+
+ /*
* Get our bogomips.
* Update loops_per_jiffy in cpu_data. Previous call to
* smp_store_cpu_info() stored a value that is close but not as
@@ -190,11 +196,6 @@ static void smp_callin(void)
cpu_data(cpuid).loops_per_jiffy = loops_per_jiffy;
pr_debug("Stack at about %p\n", &cpuid);
- /*
- * This must be done before setting cpu_online_mask
- * or calling notify_cpu_starting.
- */
- set_cpu_sibling_map(raw_smp_processor_id());
wmb();
notify_cpu_starting(cpuid);
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 6e57edf33d75..44bf5cf417d3 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1382,12 +1382,10 @@ void __init tsc_init(void)
unsigned long calibrate_delay_is_known(void)
{
int sibling, cpu = smp_processor_id();
- struct cpumask *mask = topology_core_cpumask(cpu);
+ int constant_tsc = cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC);
+ const struct cpumask *mask = topology_core_cpumask(cpu);
- if (!tsc_disabled && !cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC))
- return 0;
-
- if (!mask)
+ if (tsc_disabled || !constant_tsc || !mask)
return 0;
sibling = cpumask_any_but(mask, cpu);