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x86/cpu/topology: Provide detect_extended_topology_early()

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To support force disabling of SMT it's required to know the number of
thread siblings early. detect_extended_topology() 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@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Thomas Gleixner 2018-06-06 00:55:39 +02:00
parent 545401f444
commit 95f3d39ccf
2 changed files with 23 additions and 9 deletions
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1
arch/x86/kernel/cpu/cpu.h
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@ -55,6 +55,7 @@ extern void init_intel_cacheinfo(struct cpuinfo_x86 *c);
extern void init_amd_cacheinfo(struct cpuinfo_x86 *c);
extern void detect_num_cpu_cores(struct cpuinfo_x86 *c);
extern int detect_extended_topology_early(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);

31
arch/x86/kernel/cpu/topology.c
View File

@ -22,17 +22,10 @@
#define BITS_SHIFT_NEXT_LEVEL(eax) ((eax) & 0x1f)
#define LEVEL_MAX_SIBLINGS(ebx) ((ebx) & 0xffff)
/*
* Check for extended topology enumeration cpuid leaf 0xb and if it
* exists, use it for populating initial_apicid and cpu topology
* detection.
*/
int detect_extended_topology(struct cpuinfo_x86 *c)
int detect_extended_topology_early(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
unsigned int eax, ebx, ecx, edx, sub_index;
unsigned int ht_mask_width, core_plus_mask_width;
unsigned int core_select_mask, core_level_siblings;
unsigned int eax, ebx, ecx, edx;
if (c->cpuid_level < 0xb)
return -1;
@ -51,10 +44,30 @@ int detect_extended_topology(struct cpuinfo_x86 *c)
* initial apic id, which also represents 32-bit extended x2apic id.
*/
c->initial_apicid = edx;
smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
#endif
return 0;
}
/*
* Check for extended topology enumeration cpuid leaf 0xb and if it
* exists, use it for populating initial_apicid and cpu topology
* detection.
*/
int detect_extended_topology(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
unsigned int eax, ebx, ecx, edx, sub_index;
unsigned int ht_mask_width, core_plus_mask_width;
unsigned int core_select_mask, core_level_siblings;
if (detect_extended_topology_early(c) < 0)
return -1;
/*
* Populate HT related information from sub-leaf level 0.
*/
cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);