4.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit 545401f4448a807b963ff17b575e0a393e68b523 upstream
To support force disabling of SMT it's required to know the number of
thread siblings early. detect_ht() cannot be called before the APIC driver
is selected, so split out the part which initializes smp_num_siblings.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/common.c | 24 ++++++++++++++----------
arch/x86/kernel/cpu/cpu.h | 1 +
2 files changed, 15 insertions(+), 10 deletions(-)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -638,32 +638,36 @@ static void cpu_detect_tlb(struct cpuinf
tlb_lld_4m[ENTRIES], tlb_lld_1g[ENTRIES]);
}
-void detect_ht(struct cpuinfo_x86 *c)
+int detect_ht_early(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
u32 eax, ebx, ecx, edx;
- int index_msb, core_bits;
if (!cpu_has(c, X86_FEATURE_HT))
- return;
+ return -1;
if (cpu_has(c, X86_FEATURE_CMP_LEGACY))
- return;
+ return -1;
if (cpu_has(c, X86_FEATURE_XTOPOLOGY))
- return;
+ return -1;
cpuid(1, &eax, &ebx, &ecx, &edx);
smp_num_siblings = (ebx & 0xff0000) >> 16;
+ if (smp_num_siblings == 1)
+ pr_info_once("CPU0: Hyper-Threading is disabled\n");
+#endif
+ return 0;
+}
- if (!smp_num_siblings)
- smp_num_siblings = 1;
+void detect_ht(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+ int index_msb, core_bits;
- if (smp_num_siblings == 1) {
- pr_info_once("CPU0: Hyper-Threading is disabled\n");
+ if (detect_ht_early(c) < 0)
return;
- }
index_msb = get_count_order(smp_num_siblings);
c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, index_msb);
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -47,6 +47,7 @@ extern const struct cpu_dev *const __x86
extern void get_cpu_cap(struct cpuinfo_x86 *c);
extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
+extern int detect_ht_early(struct cpuinfo_x86 *c);
unsigned int aperfmperf_get_khz(int cpu);
