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 <[email protected]>
Tested-by: Yazen Ghannam <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: <[email protected]> # v4.6+
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: 8196dab4fc15 ("x86/cpu: Get rid of compute_unit_id")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 71cae73a507617a2559aa0815a9e178a22f33385..1d3167269a6717902149171fe755123a5c654eb6 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