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perf/x86/amd/uncore: Get correct number of cores sharing last level cache

In Family 17h, the number of cores sharing a cache level is obtained
from the Cache Properties CPUID leaf (0x8000001d) by passing in the
cache level in ECX. In prior families, a cache level of 2 was used to
determine this information.

To get the right information, irrespective of Family, iterate over
the cache levels using CPUID 0x8000001d. The last level cache is the
last value to return a non-zero value in EAX.

Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5ab569025b39cdfaeca55b571d78c0fc800bdb69.1497452002.git.Janakarajan.Natarajan@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

authored by

Janakarajan Natarajan and committed by
Ingo Molnar ab027620 910448bb

+16 -3
+16 -3
arch/x86/events/amd/uncore.c
··· 400 400 401 401 if (amd_uncore_llc) { 402 402 unsigned int apicid = cpu_data(cpu).apicid; 403 - unsigned int nshared; 403 + unsigned int nshared, subleaf, prev_eax = 0; 404 404 405 405 uncore = *per_cpu_ptr(amd_uncore_llc, cpu); 406 - cpuid_count(0x8000001d, 2, &eax, &ebx, &ecx, &edx); 407 - nshared = ((eax >> 14) & 0xfff) + 1; 406 + /* 407 + * Iterate over Cache Topology Definition leaves until no 408 + * more cache descriptions are available. 409 + */ 410 + for (subleaf = 0; subleaf < 5; subleaf++) { 411 + cpuid_count(0x8000001d, subleaf, &eax, &ebx, &ecx, &edx); 412 + 413 + /* EAX[0:4] gives type of cache */ 414 + if (!(eax & 0x1f)) 415 + break; 416 + 417 + prev_eax = eax; 418 + } 419 + nshared = ((prev_eax >> 14) & 0xfff) + 1; 420 + 408 421 uncore->id = apicid - (apicid % nshared); 409 422 410 423 uncore = amd_uncore_find_online_sibling(uncore, amd_uncore_llc);