| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 042/120] x86/CPU/AMD: Fix Bulldozer topology | Date | Wed, 18 Jan 2017 11:46:00 +0100 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Borislav Petkov <bp@suse.de>
commit a33d331761bc5dd330499ca5ceceb67f0640a8e6 upstream.
The following commit:
8196dab4fc15 ("x86/cpu: Get rid of compute_unit_id")
... broke the initial strategy for Bulldozer-based cores' topology, where we consider each thread of a compute unit a standalone core and not a HT or SMT thread.
Revert to the firmware-supplied core_id numbering and do not make them thread siblings as we don't consider them for such even if they technically are, more or less.
Reported-and-tested-by: Brice Goglin <Brice.Goglin@inria.fr> Tested-by: Yazen Ghannam <yazen.ghannam@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 8196dab4fc15 ("x86/cpu: Get rid of compute_unit_id") Link: http://lkml.kernel.org/r/20170105092638.5247-1-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/x86/kernel/cpu/amd.c | 9 +-------- 1 file changed, 1 insertion(+), 8 deletions(-)
--- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -309,15 +309,8 @@ static void amd_get_topology(struct cpui /* get information required for multi-node processors */ if (boot_cpu_has(X86_FEATURE_TOPOEXT)) { - u32 eax, ebx, ecx, edx; - cpuid(0x8000001e, &eax, &ebx, &ecx, &edx); - node_id = ecx & 7; - - /* get compute unit information */ - smp_num_siblings = ((ebx >> 8) & 3) + 1; - c->x86_max_cores /= smp_num_siblings; - c->cpu_core_id = ebx & 0xff; + node_id = cpuid_ecx(0x8000001e) & 7; /* * We may have multiple LLCs if L3 caches exist, so check if we
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