From 2760f5a415c3b86c6394738c6cff740c8b4ce664 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 6 May 2022 15:54:01 -0700 Subject: stop_machine: Add stop_core_cpuslocked() for per-core operations Hardware core level testing features require near simultaneous execution of WRMSR instructions on all threads of a core to initiate a test. Provide a customized cut down version of stop_machine_cpuslocked() that just operates on the threads of a single core. Suggested-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Tony Luck Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20220506225410.1652287-4-tony.luck@intel.com Signed-off-by: Hans de Goede --- kernel/stop_machine.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'kernel/stop_machine.c') diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index cbc30271ea4d..0887b3af609e 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -633,6 +633,27 @@ int stop_machine(cpu_stop_fn_t fn, void *data, const struct cpumask *cpus) } EXPORT_SYMBOL_GPL(stop_machine); +#ifdef CONFIG_SCHED_SMT +int stop_core_cpuslocked(unsigned int cpu, cpu_stop_fn_t fn, void *data) +{ + const struct cpumask *smt_mask = cpu_smt_mask(cpu); + + struct multi_stop_data msdata = { + .fn = fn, + .data = data, + .num_threads = cpumask_weight(smt_mask), + .active_cpus = smt_mask, + }; + + lockdep_assert_cpus_held(); + + /* Set the initial state and stop all online cpus. */ + set_state(&msdata, MULTI_STOP_PREPARE); + return stop_cpus(smt_mask, multi_cpu_stop, &msdata); +} +EXPORT_SYMBOL_GPL(stop_core_cpuslocked); +#endif + /** * stop_machine_from_inactive_cpu - stop_machine() from inactive CPU * @fn: the function to run -- cgit v1.2.3