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From:   "Day, Michael" <Michael.Day@amd.com>
To:     "Bilbao, Carlos" <Carlos.Bilbao@amd.com>,
        "bp@alien8.de" <bp@alien8.de>
CC:     "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "Ghannam, Yazen" <Yazen.Ghannam@amd.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-edac@vger.kernel.org" <linux-edac@vger.kernel.org>,
        "bilbao@vt.edu" <bilbao@vt.edu>
Subject: RE: [PATCH v2 2/2] x86/mce: Add messages to describe panic machine
 errors on AMD's MCEs grading
Thread-Topic: [PATCH v2 2/2] x86/mce: Add messages to describe panic machine
 errors on AMD's MCEs grading
Thread-Index: AQHYRR3j44TaXVxQiUqpHxQyQ+9VIazZukvQ
Date:   Thu, 31 Mar 2022 17:17:45 +0000
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References: <20220331163849.6850-1-carlos.bilbao@amd.com>
 <20220331163849.6850-3-carlos.bilbao@amd.com>
In-Reply-To: <20220331163849.6850-3-carlos.bilbao@amd.com>
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[AMD Official Use Only]

-----Original Message-----
From: Bilbao, Carlos <Carlos.Bilbao@amd.com>=20
Sent: Thursday, March 31, 2022 12:39 PM
To: bp@alien8.de
Cc: tglx@linutronix.de; mingo@redhat.com; dave.hansen@linux.intel.com; x86@=
kernel.org; Ghannam, Yazen <Yazen.Ghannam@amd.com>; linux-kernel@vger.kerne=
l.org; linux-edac@vger.kernel.org; bilbao@vt.edu; Bilbao, Carlos <Carlos.Bi=
lbao@amd.com>
Subject: [PATCH v2 2/2] x86/mce: Add messages to describe panic machine err=
ors on AMD's MCEs grading

When a machine error is graded as PANIC by AMD grading logic, the MCE handl=
er calls mce_panic(). The notification chain does not come into effect so t=
he AMD EDAC driver does not decode the errors. In these cases, the messages=
 displayed to the user are more cryptic and miss information that might be =
relevant, like the context in which the error took place.

Fix the above issue including messages on AMD's grading logic for machine e=
rrors graded as PANIC.

Signed-off-by: Carlos Bilbao <carlos.bilbao@amd.com>
---
 arch/x86/kernel/cpu/mce/severity.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/s=
everity.c
index 4d52eef21230..ea4b9407bbad 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -307,6 +307,7 @@ static noinstr int error_context(struct mce *m, struct =
pt_regs *regs)  static noinstr int mce_severity_amd(struct mce *m, struct p=
t_regs *regs, char **msg, bool is_excp)  {
 	int ret;
+	char *panic_msg;

I suggest char *panic_msg =3D NULL;

Simply because its stack-based and a non-null value may get assigned to *ms=
g after the amd_severity: label.=20
=20
 	/*
 	 * Default return value: Action required, the error must be handled @@ -3=
16,6 +317,7 @@ static noinstr int mce_severity_amd(struct mce *m, struct pt=
_regs *regs, char **
=20
 	/* Processor Context Corrupt, no need to fumble too much, die! */
 	if (m->status & MCI_STATUS_PCC) {
+		panic_msg =3D "Processor Context Corrupt";
 		ret =3D MCE_PANIC_SEVERITY;
 		goto amd_severity;
 	}
@@ -339,16 +341,21 @@ static noinstr int mce_severity_amd(struct mce *m, st=
ruct pt_regs *regs, char **
=20
 	if (((m->status & MCI_STATUS_OVER) && !mce_flags.overflow_recov)
 	     || !mce_flags.succor) {
+		panic_msg =3D "Uncorrected unrecoverable error";
 		ret =3D MCE_PANIC_SEVERITY;
 		goto amd_severity;
 	}
=20
 	if (error_context(m, regs) =3D=3D IN_KERNEL) {
+		panic_msg =3D "Uncorrected error in kernel context";
 		ret =3D MCE_PANIC_SEVERITY;
 	}
=20
 amd_severity:
=20
+	if (msg && panic_msg)
+		*msg =3D panic_msg;
+
 	return ret;
 }
=20
--
2.31.1