| From | Ben Hutchings <> | Date | Mon, 14 Nov 2016 00:14:20 +0000 | Subject | [PATCH 3.16 245/346] x86/AMD: Apply erratum 665 on machines without a BIOS fix |
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3.16.39-rc1 review patch. If anyone has any objections, please let me know.
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From: Emanuel Czirai <icanrealizeum@gmail.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@gmail.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Yaowu Xu <yaowu@google.com> Link: http://lkml.kernel.org/r/20160902053550.18097-1-bp@alien8.de Signed-off-by: Thomas Gleixner <tglx@linutronix.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@decadent.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) &&
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