Merge branch 'for-5.1/nfit/ars' into libnvdimm-for-next

Merge several updates to the ARS implementation. Highlights include:

* Support retrieval of short-ARS results if the ARS state is "requires
  continuation", and even if the "no_init_ars" module parameter is
  specified.
* Allow busy-polling of the kernel ARS state by allowing root to reset
  the exponential back-off timer.
* Filter potentially stale ARS results by tracking query-ARS relative to
  the previous start-ARS.

1 files changed, 5 insertions, 33 deletions

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 91d5c38eb7e5..d1c6d152da89 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -376,9 +376,6 @@ void __weak arch_smt_update(void) { }
 
 #ifdef CONFIG_HOTPLUG_SMT
 enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED;
-EXPORT_SYMBOL_GPL(cpu_smt_control);
-
-static bool cpu_smt_available __read_mostly;
 
 void __init cpu_smt_disable(bool force)
 {
@@ -397,25 +394,11 @@ void __init cpu_smt_disable(bool force)
 
 /*
  * The decision whether SMT is supported can only be done after the full
- * CPU identification. Called from architecture code before non boot CPUs
- * are brought up.
- */
-void __init cpu_smt_check_topology_early(void)
-{
-        if (!topology_smt_supported())
-                cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
-}
-
-/*
- * If SMT was disabled by BIOS, detect it here, after the CPUs have been
- * brought online. This ensures the smt/l1tf sysfs entries are consistent
- * with reality. cpu_smt_available is set to true during the bringup of non
- * boot CPUs when a SMT sibling is detected. Note, this may overwrite
- * cpu_smt_control's previous setting.
+ * CPU identification. Called from architecture code.
  */
 void __init cpu_smt_check_topology(void)
 {
-        if (!cpu_smt_available)
+        if (!topology_smt_supported())
                 cpu_smt_control = CPU_SMT_NOT_SUPPORTED;
 }
 
@@ -428,18 +411,10 @@ early_param("nosmt", smt_cmdline_disable);
 
 static inline bool cpu_smt_allowed(unsigned int cpu)
 {
-        if (topology_is_primary_thread(cpu))
+        if (cpu_smt_control == CPU_SMT_ENABLED)
                 return true;
 
-        /*
-         * If the CPU is not a 'primary' thread and the booted_once bit is
-         * set then the processor has SMT support. Store this information
-         * for the late check of SMT support in cpu_smt_check_topology().
-         */
-        if (per_cpu(cpuhp_state, cpu).booted_once)
-                cpu_smt_available = true;
-
-        if (cpu_smt_control == CPU_SMT_ENABLED)
+        if (topology_is_primary_thread(cpu))
                 return true;
 
         /*
@@ -2090,10 +2065,8 @@ static int cpuhp_smt_disable(enum cpuhp_smt_control ctrlval)
                  */
                 cpuhp_offline_cpu_device(cpu);
         }
-        if (!ret) {
+        if (!ret)
                 cpu_smt_control = ctrlval;
-                arch_smt_update();
-        }
         cpu_maps_update_done();
         return ret;
 }
@@ -2104,7 +2077,6 @@ static int cpuhp_smt_enable(void)
 
         cpu_maps_update_begin();
         cpu_smt_control = CPU_SMT_ENABLED;
-        arch_smt_update();
         for_each_present_cpu(cpu) {
                 /* Skip online CPUs and CPUs on offline nodes */
                 if (cpu_online(cpu) || !node_online(cpu_to_node(cpu)))