Merge branch 'core-speculation-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull speculation mitigation update from Ingo Molnar:
 "This adds the "mitigations=" bootline option, which offers a
  cross-arch set of options that will work on x86, PowerPC and s390 that
  will map to the arch specific option internally"

* 'core-speculation-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  s390/speculation: Support 'mitigations=' cmdline option
  powerpc/speculation: Support 'mitigations=' cmdline option
  x86/speculation: Support 'mitigations=' cmdline option
  cpu/speculation: Add 'mitigations=' cmdline option

1 files changed, 15 insertions, 0 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 6754f3ecfd94..43e741e88691 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2304,3 +2304,18 @@ void __init boot_cpu_hotplug_init(void)
 #endif
 	this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
 }
+
+enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO;
+
+static int __init mitigations_parse_cmdline(char *arg)
+{
+	if (!strcmp(arg, "off"))
+		cpu_mitigations = CPU_MITIGATIONS_OFF;
+	else if (!strcmp(arg, "auto"))
+		cpu_mitigations = CPU_MITIGATIONS_AUTO;
+	else if (!strcmp(arg, "auto,nosmt"))
+		cpu_mitigations = CPU_MITIGATIONS_AUTO_NOSMT;
+
+	return 0;
+}
+early_param("mitigations", mitigations_parse_cmdline);