x86/CPU/AMD: Fix Bulldozer topology

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: <stable@vger.kernel.org> # v4.6+
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>

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 71cae73..1d31672 100644 (file)
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -309,15 +309,8 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
 
        /* 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