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Commit 95f3d39c authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/cpu/topology: Provide detect_extended_topology_early() 



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: 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 545401f4

arch/x86/kernel/cpu/cpu.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/cpu/topology.c

+22 −9
Original line number Diff line number Diff line
@@ -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);