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x86/cpu/amd: Limit cpu_core_id fixup to families older than F17h

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commit b89b41d0b8 upstream.

Current cpu_core_id fixup causes downcored F17h configurations to be
incorrect:

  NODE: 0
  processor  0 core id : 0
  processor  1 core id : 1
  processor  2 core id : 2
  processor  3 core id : 4
  processor  4 core id : 5
  processor  5 core id : 0

  NODE: 1
  processor  6 core id : 2
  processor  7 core id : 3
  processor  8 core id : 4
  processor  9 core id : 0
  processor 10 core id : 1
  processor 11 core id : 2

Code that relies on the cpu_core_id, like match_smt(), for example,
which builds the thread siblings masks used by the scheduler, is
mislead.

So, limit the fixup to pre-F17h machines. The new value for cpu_core_id
for F17h and later will represent the CPUID_Fn8000001E_EBX[CoreId],
which is guaranteed to be unique for each core within a socket.

This way we have:

  NODE: 0
  processor  0 core id : 0
  processor  1 core id : 1
  processor  2 core id : 2
  processor  3 core id : 4
  processor  4 core id : 5
  processor  5 core id : 6

  NODE: 1
  processor  6 core id : 8
  processor  7 core id : 9
  processor  8 core id : 10
  processor  9 core id : 12
  processor 10 core id : 13
  processor 11 core id : 14

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
[ Heavily massaged. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yazen Ghannam <Yazen.Ghannam@amd.com>
Link: http://lkml.kernel.org/r/20170731085159.9455-2-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Suravee Suthikulpanit
2017-07-31 10:51:58 +02:00
committed by Greg Kroah-Hartman
parent b4f17de89e
commit 4edf4ad2e7
1 changed files with 17 additions and 7 deletions
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24
arch/x86/kernel/cpu/amd.c
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@@ -304,6 +304,22 @@ static void amd_get_topology_early(struct cpuinfo_x86 *c)
smp_num_siblings = ((cpuid_ebx(0x8000001e) >> 8) & 0xff) + 1;
}
/*
* Fix up cpu_core_id for pre-F17h systems to be in the
* [0 .. cores_per_node - 1] range. Not really needed but
* kept so as not to break existing setups.
*/
static void legacy_fixup_core_id(struct cpuinfo_x86 *c)
{
u32 cus_per_node;
if (c->x86 >= 0x17)
return;
cus_per_node = c->x86_max_cores / nodes_per_socket;
c->cpu_core_id %= cus_per_node;
}
/*
* Fixup core topology information for
* (1) AMD multi-node processors
@@ -359,15 +375,9 @@ static void amd_get_topology(struct cpuinfo_x86 *c)
} else
return;
/* fixup multi-node processor information */
if (nodes_per_socket > 1) {
u32 cus_per_node;
set_cpu_cap(c, X86_FEATURE_AMD_DCM);
cus_per_node = c->x86_max_cores / nodes_per_socket;
/* core id has to be in the [0 .. cores_per_node - 1] range */
c->cpu_core_id %= cus_per_node;
legacy_fixup_core_id(c);
}
}
#endif