Messages in this thread | | | Date | Wed, 12 Sep 2018 21:14:48 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [PATCH v6 2/3] x86/speculation: Enable cross-hyperthread spectre v2 STIBP mitigation |
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On Wed, 12 Sep 2018, Jiri Kosina wrote: > case X86_BUG_SPECTRE_V2: > - return sprintf(buf, "%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], > + mutex_lock(&spec_ctrl_mutex); > + ret = sprintf(buf, "%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], > boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : "", > boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", > + (x86_spec_ctrl_base & SPEC_CTRL_STIBP) ? ", STIBP" : "", > spectre_v2_module_string()); > + mutex_unlock(&spec_ctrl_mutex);
The mutex for this printing is overkill. It's a read after all and if there is a concurrent SMT control fiddling going on then you have a chance of getting the wrong information as well. I'll zap it.
Thanks,
tglx
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