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 <d...@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.
