linux-kernel - [PATCH] x86/cpu/amd: Make erratum #1054 a legacy erratum

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Message-Id: <20200417143356.26054-1-kim.phillips@amd.com>
Date:   Fri, 17 Apr 2020 09:33:56 -0500
From:   Kim Phillips <kim.phillips@....com>
To:     Borislav Petkov <bp@...en8.de>, Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>, kim.phillips@....com
Cc:     Andrew Cooper <andrew.cooper3@...rix.com>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Frank van der Linden <fllinden@...zon.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86/cpu/amd: Make erratum #1054 a legacy erratum

Commit

  21b5ee59ef18 ("x86/cpu/amd: Enable the fixed Instructions Retired
		 counter IRPERF")

mistakenly added erratum #1054 as OS Visible Work-around (OSVW)
ID 0.  Erratum #1054 is not OSVW ID 0 [1], so make it a legacy
erratum.

There would never have been a false positive on older hardware that
has OSVW bit 0 set, since the IRPERF feature was not available.

We do however save a couple of rdmsrs per thread, on modern system
configurations that correctly set non-zero values in their
OSVW_ID_Length MSRs.

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

The revision guide is available from the bugzilla link below.

Fixes: 21b5ee59ef18 ("x86/cpu/amd: Enable the fixed Instructions Retired counter IRPERF")
Reported-by: Andrew Cooper <andrew.cooper3@...rix.com>
Signed-off-by: Kim Phillips <kim.phillips@....com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
Cc: Borislav Petkov <bp@...e.de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Frank van der Linden <fllinden@...zon.com>
Cc: x86@...nel.org
Cc: linux-kernel@...r.kernel.org
---
 arch/x86/kernel/cpu/amd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 1f875fbe1384..8caf29706eac 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -1111,7 +1111,7 @@ static const int amd_erratum_383[] =
 
 /* #1054: Instructions Retired Performance Counter May Be Inaccurate */
 static const int amd_erratum_1054[] =
-	AMD_OSVW_ERRATUM(0, AMD_MODEL_RANGE(0x17, 0, 0, 0x2f, 0xf));
+	AMD_LEGACY_ERRATUM(AMD_MODEL_RANGE(0x17, 0, 0, 0x2f, 0xf));
 
 
 static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum)
-- 
2.20.1