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-rw-r--r--arch/x86/kernel/smp.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 18266cc3d98c..b014e6d229f9 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -299,3 +299,27 @@ struct smp_ops smp_ops = {
.send_call_func_single_ipi = native_send_call_func_single_ipi,
};
EXPORT_SYMBOL_GPL(smp_ops);
+
+int arch_cpu_rescan_dead_smt_siblings(void)
+{
+ enum cpuhp_smt_control old = cpu_smt_control;
+ int ret;
+
+ /*
+ * If SMT has been disabled and SMT siblings are in HLT, bring them back
+ * online and offline them again so that they end up in MWAIT proper.
+ *
+ * Called with hotplug enabled.
+ */
+ if (old != CPU_SMT_DISABLED && old != CPU_SMT_FORCE_DISABLED)
+ return 0;
+
+ ret = cpuhp_smt_enable();
+ if (ret)
+ return ret;
+
+ ret = cpuhp_smt_disable(old);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(arch_cpu_rescan_dead_smt_siblings);