Messages in this thread | | | Date | Sun, 22 Oct 2017 15:04:29 +0200 | From | Peter Zijlstra <> | Subject | Re: [tip:x86/urgent] x86/cpu/AMD: Apply the Erratum 688 fix when the BIOS doesn't |
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On Sun, Oct 22, 2017 at 05:16:29AM -0700, tip-bot for Borislav Petkov wrote: > +static void __fix_erratum_688(void *info) > +{ > +#define MSR_AMD64_IC_CFG 0xC0011021 > + > + msr_set_bit(MSR_AMD64_IC_CFG, 3); > + msr_set_bit(MSR_AMD64_IC_CFG, 14);
I realize this is an erratum work around, but would it be too much to ask for a small comment explaining the magic values?
> +} > + > +/* Apply erratum 688 fix so machines without a BIOS fix work. */ > +static __init void fix_erratum_688(void) > +{ > + struct pci_dev *F4; > + u32 val; > + > + if (boot_cpu_data.x86 != 0x14) > + return; > + > + if (!amd_northbridges.num) > + return; > + > + F4 = node_to_amd_nb(0)->link; > + if (!F4) > + return; > + > + if (pci_read_config_dword(F4, 0x164, &val)) > + return; > + > + if (val & BIT(2)) > + return; > + > + on_each_cpu(__fix_erratum_688, NULL, 0); > + > + pr_info("x86/cpu/AMD: CPU erratum 688 worked around\n");
Except for all CPUs that were not online at this point in time... So suppose I boot with a limited number of CPUs and then later bring up the rest, bad things happen.
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