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STIBP is a feature provided by certain Intel ucodes / CPUs. This feature (once enabled) prevents cross-hyperthread control of decisions made by indirect branch predictors. Enable this feature if - the CPU is vulnerable to spectre v2 - the CPU supports SMT and has SMT siblings online - spectre_v2 mitigation autoselection is enabled (default) After some previous discussion, this leaves STIBP on all the time, as wrmsr on crossing kernel boundary is a no-no. This could perhaps later be a bit more optimized (like disabling it in NOHZ, experiment with disabling it in idle, etc) if needed. Note that the synchronization of the mask manipulation via newly added spec_ctrl_mutex is currently not strictly needed, as the only updater is already being serialized by cpu_add_remove_lock, but let's make this a little bit more future-proof. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: "WoodhouseDavid" <dwmw@amazon.co.uk> Cc: Andi Kleen <ak@linux.intel.com> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: "SchauflerCasey" <casey.schaufler@intel.com> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/nycvar.YFH.7.76.1809251438240.15880@cbobk.fhfr.pm |
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| mcheck | ||
| microcode | ||
| mtrr | ||
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| bugs.c | ||
| cacheinfo.c | ||
| centaur.c | ||
| common.c | ||
| cpu.h | ||
| cpuid-deps.c | ||
| cyrix.c | ||
| hypervisor.c | ||
| intel_pconfig.c | ||
| intel_rdt_ctrlmondata.c | ||
| intel_rdt_monitor.c | ||
| intel_rdt_pseudo_lock_event.h | ||
| intel_rdt_pseudo_lock.c | ||
| intel_rdt_rdtgroup.c | ||
| intel_rdt.c | ||
| intel_rdt.h | ||
| intel.c | ||
| Makefile | ||
| match.c | ||
| mkcapflags.sh | ||
| mshyperv.c | ||
| perfctr-watchdog.c | ||
| powerflags.c | ||
| proc.c | ||
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| scattered.c | ||
| topology.c | ||
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