cpu/speculation: Uninline and export CPU mitigations helpers

BugLink: https://bugs.launchpad.net/bugs/1852338
commit 731dc9df975a5da21237a18c3384f811a7a41cc6 upstream.

A kernel module may need to check the value of the "mitigations=" kernel
command line parameter as part of its setup when the module needs
to perform software mitigations for a CPU flaw.

Uninline and export the helper functions surrounding the cpu_mitigations
enum to allow for their usage from a module.

Lastly, privatize the enum and cpu_mitigations variable since the value of
cpu_mitigations can be checked with the exported helper functions.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 3ba20e94e51a60e96d064718b9751ca0aff77134..4643fcf554742945423397bc139fa0fa4f5df29c 100644 (file)
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -216,28 +216,7 @@ static inline int cpuhp_smt_enable(void) { return 0; }
 static inline int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval) { return 0; }
 #endif
 
-/*
- * These are used for a global "mitigations=" cmdline option for toggling
- * optional CPU mitigations.
- */
-enum cpu_mitigations {
-       CPU_MITIGATIONS_OFF,
-       CPU_MITIGATIONS_AUTO,
-       CPU_MITIGATIONS_AUTO_NOSMT,
-};
-
-extern enum cpu_mitigations cpu_mitigations;
-
-/* mitigations=off */
-static inline bool cpu_mitigations_off(void)
-{
-       return cpu_mitigations == CPU_MITIGATIONS_OFF;
-}
-
-/* mitigations=auto,nosmt */
-static inline bool cpu_mitigations_auto_nosmt(void)
-{
-       return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;
-}
+extern bool cpu_mitigations_off(void);
+extern bool cpu_mitigations_auto_nosmt(void);
 
 #endif /* _LINUX_CPU_H_ */

diff --git a/kernel/cpu.c b/kernel/cpu.c
index e84c0873559ed3f4dff968a6240293bb22f0978b..df186823dda675f37988051c663678d98f48c9f6 100644 (file)
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -2339,7 +2339,18 @@ void __init boot_cpu_hotplug_init(void)
        this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
 }
 
-enum cpu_mitigations cpu_mitigations __ro_after_init = CPU_MITIGATIONS_AUTO;
+/*
+ * These are used for a global "mitigations=" cmdline option for toggling
+ * optional CPU mitigations.
+ */
+enum cpu_mitigations {
+       CPU_MITIGATIONS_OFF,
+       CPU_MITIGATIONS_AUTO,
+       CPU_MITIGATIONS_AUTO_NOSMT,
+};
+
+static enum cpu_mitigations cpu_mitigations __ro_after_init =
+       CPU_MITIGATIONS_AUTO;
 
 static int __init mitigations_parse_cmdline(char *arg)
 {
@@ -2356,3 +2367,17 @@ static int __init mitigations_parse_cmdline(char *arg)
        return 0;
 }
 early_param("mitigations", mitigations_parse_cmdline);
+
+/* mitigations=off */
+bool cpu_mitigations_off(void)
+{
+       return cpu_mitigations == CPU_MITIGATIONS_OFF;
+}
+EXPORT_SYMBOL_GPL(cpu_mitigations_off);
+
+/* mitigations=auto,nosmt */
+bool cpu_mitigations_auto_nosmt(void)
+{
+       return cpu_mitigations == CPU_MITIGATIONS_AUTO_NOSMT;
+}
+EXPORT_SYMBOL_GPL(cpu_mitigations_auto_nosmt);