Messages in this thread | | | Subject | Re: [PATCH v2 4/8] x86/spec_ctrl: Add sysctl knobs to enable/disable SPEC_CTRL feature | From | Tim Chen <> | Date | Sat, 6 Jan 2018 10:23:09 -0800 |
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On 01/06/2018 09:33 AM, Dave Hansen wrote: > On 01/06/2018 06:41 AM, Konrad Rzeszutek Wilk wrote: >>> .macro DISABLE_IBRS >>> - ALTERNATIVE "jmp .Lskip_\@", "", X86_FEATURE_SPEC_CTRL >>> + testl $1, dynamic_ibrs >> On every system call we end up hammering on this 'dynamic_ibrs' >> variable. And it looks like it can be flipped via the IPI mechanism. >> >> Would it make sense for this to be per-cpu? > > It's probably better to either just make it __read_mostly or get the > static branches that folks were suggesting actually working. >
dynamic_ibrs is indeed declared __read_mostly
+unsigned int dynamic_ibrs __read_mostly; +EXPORT_SYMBOL_GPL(dynamic_ibrs);
Tim
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