Messages in this thread Patch in this message |  | | Date | Tue, 30 Jan 2018 11:58:14 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/cpuid: Fix up "virtual" IBRS/IBPB/STIBP feature bits on Intel |
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On Mon, Jan 29, 2018 at 11:49:33PM +0000, David Woodhouse wrote: > Despite the fact that all the other code there seems to be doing it, > just using set_cpu_cap() in early_intel_init() doesn't actually work. > > When the CPU is queried again in identify_boot_cpu(), it all gets > overwritten again. Do it in init_scattered_cpuid_features() instead. > > Turning the bits off for bad microcode can use setup_clear_cpu_cap() > to force them off for all CPUs; I was less keen on forcing the feature > bits *on* that way. > > Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> > Fixes: 2961298e ("x86/cpufeatures: Clean up Spectre v2 related CPUID flags") > --- > I feel I must be missing something. Is the rest of early_init_intel() broken too?
Does that help?
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index 6936d14d4c77..1dd596d0a6c4 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -182,21 +182,21 @@ static void early_init_intel(struct cpuinfo_x86 *c) * Intel CPUs, for finer-grained selection of what's available. */ if (cpu_has(c, X86_FEATURE_SPEC_CTRL)) { - set_cpu_cap(c, X86_FEATURE_IBRS); - set_cpu_cap(c, X86_FEATURE_IBPB); + setup_force_cpu_cap(X86_FEATURE_IBRS); + setup_force_cpu_cap(X86_FEATURE_IBPB); } if (cpu_has(c, X86_FEATURE_INTEL_STIBP)) - set_cpu_cap(c, X86_FEATURE_STIBP); + setup_force_cpu_cap(X86_FEATURE_STIBP); /* Now if any of them are set, check the blacklist and clear the lot */ if ((cpu_has(c, X86_FEATURE_IBRS) || cpu_has(c, X86_FEATURE_IBPB) || cpu_has(c, X86_FEATURE_STIBP)) && bad_spectre_microcode(c)) { pr_warn("Intel Spectre v2 broken microcode detected; disabling Speculation Control\n"); - clear_cpu_cap(c, X86_FEATURE_IBRS); - clear_cpu_cap(c, X86_FEATURE_IBPB); - clear_cpu_cap(c, X86_FEATURE_STIBP); - clear_cpu_cap(c, X86_FEATURE_SPEC_CTRL); - clear_cpu_cap(c, X86_FEATURE_INTEL_STIBP); + setup_clear_cpu_cap(X86_FEATURE_IBRS); + setup_clear_cpu_cap(X86_FEATURE_IBPB); + setup_clear_cpu_cap(X86_FEATURE_STIBP); + setup_clear_cpu_cap(X86_FEATURE_SPEC_CTRL); + setup_clear_cpu_cap(X86_FEATURE_INTEL_STIBP); } /* -- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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