Merge pull request #76 from toradex/4.9-2.3.x-imx

4.9 2.3.x imx

1 files changed, 33 insertions, 0 deletions

diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c
index fef485b789ca..6120046bb7dd 100644
--- a/arch/x86/power/hibernate_64.c
+++ b/arch/x86/power/hibernate_64.c
@@ -11,6 +11,7 @@
 #include <linux/gfp.h>
 #include <linux/smp.h>
 #include <linux/suspend.h>
+#include <linux/cpu.h>
 
 #include <asm/init.h>
 #include <asm/proto.h>
@@ -218,3 +219,35 @@ int arch_hibernation_header_restore(void *addr)
 	restore_cr3 = rdr->cr3;
 	return (rdr->magic == RESTORE_MAGIC) ? 0 : -EINVAL;
 }
+
+int arch_resume_nosmt(void)
+{
+	int ret = 0;
+	/*
+	 * We reached this while coming out of hibernation. This means
+	 * that SMT siblings are sleeping in hlt, as mwait is not safe
+	 * against control transition during resume (see comment in
+	 * hibernate_resume_nonboot_cpu_disable()).
+	 *
+	 * If the resumed kernel has SMT disabled, we have to take all the
+	 * SMT siblings out of hlt, and offline them again so that they
+	 * end up in mwait proper.
+	 *
+	 * Called with hotplug disabled.
+	 */
+	cpu_hotplug_enable();
+	if (cpu_smt_control == CPU_SMT_DISABLED ||
+			cpu_smt_control == CPU_SMT_FORCE_DISABLED) {
+		enum cpuhp_smt_control old = cpu_smt_control;
+
+		ret = cpuhp_smt_enable();
+		if (ret)
+			goto out;
+		ret = cpuhp_smt_disable(old);
+		if (ret)
+			goto out;
+	}
+out:
+	cpu_hotplug_disable();
+	return ret;
+}