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x86/cpu/amd: Enable the fixed Instructions Retired counter IRPERF

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  aaf248848d ("perf/x86/msr: Add AMD IRPERF (Instructions Retired)
		  performance counter")

added support for access to the free-running counter via 'perf -e
msr/irperf/', but when exercised, it always returns a 0 count:

BEFORE:

  $ perf stat -e instructions,msr/irperf/ true

   Performance counter stats for 'true':

             624,833      instructions
                   0      msr/irperf/

Simply set its enable bit - HWCR bit 30 - to make it start counting.

Enablement is restricted to all machines advertising IRPERF capability,
except those susceptible to an erratum that makes the IRPERF return
bad values.

That erratum occurs in Family 17h models 00-1fh [1], but not in F17h
models 20h and above [2].

AFTER (on a family 17h model 31h machine):

  $ perf stat -e instructions,msr/irperf/ true

   Performance counter stats for 'true':

             621,690      instructions
             622,490      msr/irperf/

[1] Revision Guide for AMD Family 17h Models 00h-0Fh Processors
[2] Revision Guide for AMD Family 17h Models 30h-3Fh Processors

The revision guides are available from the bugzilla Link below.

 [ bp: Massage commit message. ]

Fixes: aaf248848d ("perf/x86/msr: Add AMD IRPERF (Instructions Retired) performance counter")
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Link: http://lkml.kernel.org/r/20200214201805.13830-1-kim.phillips@amd.com
This commit is contained in:
Kim Phillips
2020-02-19 18:52:43 +01:00
committed by Borislav Petkov
parent df6d4f9db7
commit 21b5ee59ef
2 changed files with 16 additions and 0 deletions
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2
arch/x86/include/asm/msr-index.h
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@@ -512,6 +512,8 @@
#define MSR_K7_HWCR 0xc0010015
#define MSR_K7_HWCR_SMMLOCK_BIT 0
#define MSR_K7_HWCR_SMMLOCK BIT_ULL(MSR_K7_HWCR_SMMLOCK_BIT)
#define MSR_K7_HWCR_IRPERF_EN_BIT 30
#define MSR_K7_HWCR_IRPERF_EN BIT_ULL(MSR_K7_HWCR_IRPERF_EN_BIT)
#define MSR_K7_FID_VID_CTL 0xc0010041
#define MSR_K7_FID_VID_STATUS 0xc0010042