Commit 545401f4 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/cpu/common: Provide detect_ht_early() 



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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
parent 44ca36de

arch/x86/kernel/cpu/common.c

+14 −10
Original line number Diff line number Diff line
@@ -658,32 +658,36 @@ static void cpu_detect_tlb(struct cpuinfo_x86 *c) 
		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);

arch/x86/kernel/cpu/cpu.h

+1 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ extern void init_amd_cacheinfo(struct cpuinfo_x86 *c); 


extern void detect_num_cpu_cores(struct cpuinfo_x86 *c);

extern int detect_extended_topology(struct cpuinfo_x86 *c);

extern int detect_ht_early(struct cpuinfo_x86 *c);

extern void detect_ht(struct cpuinfo_x86 *c);



unsigned int aperfmperf_get_khz(int cpu);

CRA Git | Maintained and supported by SUSTech CRA and CCSE