linux-kernel - [tip:perf/urgent] perf/x86/intel/uncore: Fix hardcoded socket 0 assumption in the Haswell init code

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Date:   Sun, 8 Jan 2017 22:43:21 -0800
From:   tip-bot for Prarit Bhargava <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     peterz@...radead.org, bp@...e.de, jolsa@...hat.com,
        prarit@...hat.com, vincent.weaver@...ne.edu, tglx@...utronix.de,
        hpa@...or.com, acme@...hat.com, kan.liang@...el.com,
        eranian@...gle.com, alexander.shishkin@...ux.intel.com,
        harish.chegondi@...el.com, linux-kernel@...r.kernel.org,
        mingo@...nel.org, torvalds@...ux-foundation.org
Subject: [tip:perf/urgent] perf/x86/intel/uncore: Fix hardcoded socket 0
 assumption in the Haswell init code

Commit-ID:  fa37361e291bfe528872b9aef5c8644a3fc7ff20
Gitweb:     http://git.kernel.org/tip/fa37361e291bfe528872b9aef5c8644a3fc7ff20
Author:     Prarit Bhargava <prarit@...hat.com>
AuthorDate: Thu, 5 Jan 2017 10:09:25 -0500
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Sat, 7 Jan 2017 08:54:38 +0100

perf/x86/intel/uncore: Fix hardcoded socket 0 assumption in the Haswell init code

On multi-socket Intel v3 processor systems (aka Haswell), kdump can crash
in hswep_uncore_cpu_init():

  BUG: unable to handle kernel paging request at 00000000006563a1
  IP: [<ffffffff8101b582>] hswep_uncore_cpu_init+0x52/0xa0

The crash was introduced by the following commit:

  9d85eb9119f4 ("x86/smpboot: Make logical package management more robust")

... which patch corrected the physical ID to logical ID mapping of the
threads if the kdumped panic occurs on any socket other than socket 0.

But hswep_uncore_cpu_init() is hard coded for physical socket 0 and if the
system is kdump'ing on any other socket the logical package value will be
incorrect - crashing the kdump kernel.

The code should not use 0 as the physical ID, and should use the boot
CPU's logical package ID in this calculation.

Signed-off-by: Prarit Bhargava <prarit@...hat.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Harish Chegondi <harish.chegondi@...el.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Kan Liang <kan.liang@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vince Weaver <vincent.weaver@...ne.edu>
Link: http://lkml.kernel.org/r/1483628965-2890-1-git-send-email-prarit@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/events/intel/uncore_snbep.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/uncore_snbep.c b/arch/x86/events/intel/uncore_snbep.c
index e6832be..dae2fed 100644
--- a/arch/x86/events/intel/uncore_snbep.c
+++ b/arch/x86/events/intel/uncore_snbep.c
@@ -2686,7 +2686,7 @@ static struct intel_uncore_type *hswep_msr_uncores[] = {
 
 void hswep_uncore_cpu_init(void)
 {
-	int pkg = topology_phys_to_logical_pkg(0);
+	int pkg = boot_cpu_data.logical_proc_id;
 
 	if (hswep_uncore_cbox.num_boxes > boot_cpu_data.x86_max_cores)
 		hswep_uncore_cbox.num_boxes = boot_cpu_data.x86_max_cores;