linux-kernel - [PATCH 3.16 245/346] x86/AMD: Apply erratum 665 on machines without a BIOS fix

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1479082460.543647680@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Thomas Gleixner" <tglx@...utronix.de>,
        "Emanuel Czirai" <icanrealizeum@...il.com>,
        "Borislav Petkov" <bp@...e.de>, "Yaowu Xu" <yaowu@...gle.com>
Subject: [PATCH 3.16 245/346] x86/AMD: Apply erratum 665 on machines
 without a BIOS fix

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Emanuel Czirai <icanrealizeum@...il.com>

commit d1992996753132e2dafe955cccb2fb0714d3cfc4 upstream.

AMD F12h machines have an erratum which can cause DIV/IDIV to behave
unpredictably. The workaround is to set MSRC001_1029[31] but sometimes
there is no BIOS update containing that workaround so let's do it
ourselves unconditionally. It is simple enough.

[ Borislav: Wrote commit message. ]

Signed-off-by: Emanuel Czirai <icanrealizeum@...il.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Yaowu Xu <yaowu@...gle.com>
Link: http://lkml.kernel.org/r/20160902053550.18097-1-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
[bwh: Backported to 3.16:
 - Add an if-statement to init_amd() in place of the switch
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -522,6 +522,17 @@ static const int amd_erratum_383[];
 static const int amd_erratum_400[];
 static bool cpu_has_amd_erratum(struct cpuinfo_x86 *cpu, const int *erratum);
 
+#define MSR_AMD64_DE_CFG	0xC0011029
+
+static void init_amd_ln(struct cpuinfo_x86 *c)
+{
+	/*
+	 * Apply erratum 665 fix unconditionally so machines without a BIOS
+	 * fix work.
+	 */
+	msr_set_bit(MSR_AMD64_DE_CFG, 31);
+}
+
 static void init_amd(struct cpuinfo_x86 *c)
 {
 	u32 dummy;
@@ -614,6 +625,9 @@ static void init_amd(struct cpuinfo_x86
 		}
 	}
 
+	if (c->x86 == 0x12)
+		init_amd_ln(c);
+
 	/* re-enable TopologyExtensions if switched off by BIOS */
 	if ((c->x86 == 0x15) &&
 	    (c->x86_model >= 0x10) && (c->x86_model <= 0x1f) &&