3.16.39-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Emanuel Czirai <[email protected]> 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 <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Cc: Yaowu Xu <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> [bwh: Backported to 3.16: - Add an if-statement to init_amd() in place of the switch - Adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- --- 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) &&
