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1// SPDX-License-Identifier: GPL-2.02/*3 * cpuidle-pseries - idle state cpuidle driver.4 * Adapted from drivers/idle/intel_idle.c and5 * drivers/acpi/processor_idle.c6 *7 */8 9#include <linux/kernel.h>10#include <linux/module.h>11#include <linux/init.h>12#include <linux/moduleparam.h>13#include <linux/cpuidle.h>14#include <linux/cpu.h>15#include <linux/notifier.h>16 17#include <asm/paca.h>18#include <asm/reg.h>19#include <asm/machdep.h>20#include <asm/firmware.h>21#include <asm/runlatch.h>22#include <asm/idle.h>23#include <asm/plpar_wrappers.h>24#include <asm/rtas.h>25 26static struct cpuidle_driver pseries_idle_driver = {27 .name = "pseries_idle",28 .owner = THIS_MODULE,29};30 31static int max_idle_state __read_mostly;32static struct cpuidle_state *cpuidle_state_table __read_mostly;33static u64 snooze_timeout __read_mostly;34static bool snooze_timeout_en __read_mostly;35 36static __cpuidle37int snooze_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv,38 int index)39{40 u64 snooze_exit_time;41 42 set_thread_flag(TIF_POLLING_NRFLAG);43 44 pseries_idle_prolog();45 raw_local_irq_enable();46 snooze_exit_time = get_tb() + snooze_timeout;47 dev->poll_time_limit = false;48 49 while (!need_resched()) {50 HMT_low();51 HMT_very_low();52 if (likely(snooze_timeout_en) && get_tb() > snooze_exit_time) {53 /*54 * Task has not woken up but we are exiting the polling55 * loop anyway. Require a barrier after polling is56 * cleared to order subsequent test of need_resched().57 */58 dev->poll_time_limit = true;59 clear_thread_flag(TIF_POLLING_NRFLAG);60 smp_mb();61 break;62 }63 }64 65 HMT_medium();66 clear_thread_flag(TIF_POLLING_NRFLAG);67 68 raw_local_irq_disable();69 70 pseries_idle_epilog();71 72 return index;73}74 75static __cpuidle void check_and_cede_processor(void)76{77 /*78 * Ensure our interrupt state is properly tracked,79 * also checks if no interrupt has occurred while we80 * were soft-disabled81 */82 if (prep_irq_for_idle()) {83 cede_processor();84#ifdef CONFIG_TRACE_IRQFLAGS85 /* Ensure that H_CEDE returns with IRQs on */86 if (WARN_ON(!(mfmsr() & MSR_EE)))87 __hard_irq_enable();88#endif89 }90}91 92/*93 * XCEDE: Extended CEDE states discovered through the94 * "ibm,get-systems-parameter" RTAS call with the token95 * CEDE_LATENCY_TOKEN96 */97 98/*99 * Section 7.3.16 System Parameters Option of PAPR version 2.8.1 has a100 * table with all the parameters to ibm,get-system-parameters.101 * CEDE_LATENCY_TOKEN corresponds to the token value for Cede Latency102 * Settings Information.103 */104#define CEDE_LATENCY_TOKEN 45105 106/*107 * If the platform supports the cede latency settings information system108 * parameter it must provide the following information in the NULL terminated109 * parameter string:110 *111 * a. The first byte is the length “N” of each cede latency setting record minus112 * one (zero indicates a length of 1 byte).113 *114 * b. For each supported cede latency setting a cede latency setting record115 * consisting of the first “N” bytes as per the following table.116 *117 * -----------------------------118 * | Field | Field |119 * | Name | Length |120 * -----------------------------121 * | Cede Latency | 1 Byte |122 * | Specifier Value | |123 * -----------------------------124 * | Maximum wakeup | |125 * | latency in | 8 Bytes |126 * | tb-ticks | |127 * -----------------------------128 * | Responsive to | |129 * | external | 1 Byte |130 * | interrupts | |131 * -----------------------------132 *133 * This version has cede latency record size = 10.134 *135 * The structure xcede_latency_payload represents a) and b) with136 * xcede_latency_record representing the table in b).137 *138 * xcede_latency_parameter is what gets returned by139 * ibm,get-systems-parameter RTAS call when made with140 * CEDE_LATENCY_TOKEN.141 *142 * These structures are only used to represent the data obtained by the RTAS143 * call. The data is in big-endian.144 */145struct xcede_latency_record {146 u8 hint;147 __be64 latency_ticks;148 u8 wake_on_irqs;149} __packed;150 151// Make space for 16 records, which "should be enough".152struct xcede_latency_payload {153 u8 record_size;154 struct xcede_latency_record records[16];155} __packed;156 157struct xcede_latency_parameter {158 __be16 payload_size;159 struct xcede_latency_payload payload;160 u8 null_char;161} __packed;162 163static unsigned int nr_xcede_records;164static struct xcede_latency_parameter xcede_latency_parameter __initdata;165 166static int __init parse_cede_parameters(void)167{168 struct xcede_latency_payload *payload;169 u32 total_xcede_records_size;170 u8 xcede_record_size;171 u16 payload_size;172 int ret, i;173 174 ret = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,175 NULL, CEDE_LATENCY_TOKEN, __pa(&xcede_latency_parameter),176 sizeof(xcede_latency_parameter));177 if (ret) {178 pr_err("xcede: Error parsing CEDE_LATENCY_TOKEN\n");179 return ret;180 }181 182 payload_size = be16_to_cpu(xcede_latency_parameter.payload_size);183 payload = &xcede_latency_parameter.payload;184 185 xcede_record_size = payload->record_size + 1;186 187 if (xcede_record_size != sizeof(struct xcede_latency_record)) {188 pr_err("xcede: Expected record-size %lu. Observed size %u.\n",189 sizeof(struct xcede_latency_record), xcede_record_size);190 return -EINVAL;191 }192 193 pr_info("xcede: xcede_record_size = %d\n", xcede_record_size);194 195 /*196 * Since the payload_size includes the last NULL byte and the197 * xcede_record_size, the remaining bytes correspond to array of all198 * cede_latency settings.199 */200 total_xcede_records_size = payload_size - 2;201 nr_xcede_records = total_xcede_records_size / xcede_record_size;202 203 for (i = 0; i < nr_xcede_records; i++) {204 struct xcede_latency_record *record = &payload->records[i];205 u64 latency_ticks = be64_to_cpu(record->latency_ticks);206 u8 wake_on_irqs = record->wake_on_irqs;207 u8 hint = record->hint;208 209 pr_info("xcede: Record %d : hint = %u, latency = 0x%llx tb ticks, Wake-on-irq = %u\n",210 i, hint, latency_ticks, wake_on_irqs);211 }212 213 return 0;214}215 216#define NR_DEDICATED_STATES 2 /* snooze, CEDE */217static u8 cede_latency_hint[NR_DEDICATED_STATES];218 219static __cpuidle220int dedicated_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv,221 int index)222{223 u8 old_latency_hint;224 225 pseries_idle_prolog();226 get_lppaca()->donate_dedicated_cpu = 1;227 old_latency_hint = get_lppaca()->cede_latency_hint;228 get_lppaca()->cede_latency_hint = cede_latency_hint[index];229 230 HMT_medium();231 check_and_cede_processor();232 233 raw_local_irq_disable();234 get_lppaca()->donate_dedicated_cpu = 0;235 get_lppaca()->cede_latency_hint = old_latency_hint;236 237 pseries_idle_epilog();238 239 return index;240}241 242static __cpuidle243int shared_cede_loop(struct cpuidle_device *dev, struct cpuidle_driver *drv,244 int index)245{246 247 pseries_idle_prolog();248 249 /*250 * Yield the processor to the hypervisor. We return if251 * an external interrupt occurs (which are driven prior252 * to returning here) or if a prod occurs from another253 * processor. When returning here, external interrupts254 * are enabled.255 */256 check_and_cede_processor();257 258 raw_local_irq_disable();259 pseries_idle_epilog();260 261 return index;262}263 264/*265 * States for dedicated partition case.266 */267static struct cpuidle_state dedicated_states[NR_DEDICATED_STATES] = {268 { /* Snooze */269 .name = "snooze",270 .desc = "snooze",271 .exit_latency = 0,272 .target_residency = 0,273 .enter = &snooze_loop,274 .flags = CPUIDLE_FLAG_POLLING },275 { /* CEDE */276 .name = "CEDE",277 .desc = "CEDE",278 .exit_latency = 10,279 .target_residency = 100,280 .enter = &dedicated_cede_loop },281};282 283/*284 * States for shared partition case.285 */286static struct cpuidle_state shared_states[] = {287 { /* Snooze */288 .name = "snooze",289 .desc = "snooze",290 .exit_latency = 0,291 .target_residency = 0,292 .enter = &snooze_loop,293 .flags = CPUIDLE_FLAG_POLLING },294 { /* Shared Cede */295 .name = "Shared Cede",296 .desc = "Shared Cede",297 .exit_latency = 10,298 .target_residency = 100,299 .enter = &shared_cede_loop },300};301 302static int pseries_cpuidle_cpu_online(unsigned int cpu)303{304 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);305 306 if (dev && cpuidle_get_driver()) {307 cpuidle_pause_and_lock();308 cpuidle_enable_device(dev);309 cpuidle_resume_and_unlock();310 }311 return 0;312}313 314static int pseries_cpuidle_cpu_dead(unsigned int cpu)315{316 struct cpuidle_device *dev = per_cpu(cpuidle_devices, cpu);317 318 if (dev && cpuidle_get_driver()) {319 cpuidle_pause_and_lock();320 cpuidle_disable_device(dev);321 cpuidle_resume_and_unlock();322 }323 return 0;324}325 326/*327 * pseries_cpuidle_driver_init()328 */329static int pseries_cpuidle_driver_init(void)330{331 int idle_state;332 struct cpuidle_driver *drv = &pseries_idle_driver;333 334 drv->state_count = 0;335 336 for (idle_state = 0; idle_state < max_idle_state; ++idle_state) {337 /* Is the state not enabled? */338 if (cpuidle_state_table[idle_state].enter == NULL)339 continue;340 341 drv->states[drv->state_count] = /* structure copy */342 cpuidle_state_table[idle_state];343 344 drv->state_count += 1;345 }346 347 return 0;348}349 350static void __init fixup_cede0_latency(void)351{352 struct xcede_latency_payload *payload;353 u64 min_xcede_latency_us = UINT_MAX;354 int i;355 356 if (parse_cede_parameters())357 return;358 359 pr_info("cpuidle: Skipping the %d Extended CEDE idle states\n",360 nr_xcede_records);361 362 payload = &xcede_latency_parameter.payload;363 364 /*365 * The CEDE idle state maps to CEDE(0). While the hypervisor366 * does not advertise CEDE(0) exit latency values, it does367 * advertise the latency values of the extended CEDE states.368 * We use the lowest advertised exit latency value as a proxy369 * for the exit latency of CEDE(0).370 */371 for (i = 0; i < nr_xcede_records; i++) {372 struct xcede_latency_record *record = &payload->records[i];373 u8 hint = record->hint;374 u64 latency_tb = be64_to_cpu(record->latency_ticks);375 u64 latency_us = DIV_ROUND_UP_ULL(tb_to_ns(latency_tb), NSEC_PER_USEC);376 377 /*378 * We expect the exit latency of an extended CEDE379 * state to be non-zero, it to since it takes at least380 * a few nanoseconds to wakeup the idle CPU and381 * dispatch the virtual processor into the Linux382 * Guest.383 *384 * So we consider only non-zero value for performing385 * the fixup of CEDE(0) latency.386 */387 if (latency_us == 0) {388 pr_warn("cpuidle: Skipping xcede record %d [hint=%d]. Exit latency = 0us\n",389 i, hint);390 continue;391 }392 393 if (latency_us < min_xcede_latency_us)394 min_xcede_latency_us = latency_us;395 }396 397 if (min_xcede_latency_us != UINT_MAX) {398 dedicated_states[1].exit_latency = min_xcede_latency_us;399 dedicated_states[1].target_residency = 10 * (min_xcede_latency_us);400 pr_info("cpuidle: Fixed up CEDE exit latency to %llu us\n",401 min_xcede_latency_us);402 }403 404}405 406/*407 * pseries_idle_probe()408 * Choose state table for shared versus dedicated partition409 */410static int __init pseries_idle_probe(void)411{412 413 if (cpuidle_disable != IDLE_NO_OVERRIDE)414 return -ENODEV;415 416 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {417 if (lppaca_shared_proc()) {418 cpuidle_state_table = shared_states;419 max_idle_state = ARRAY_SIZE(shared_states);420 } else {421 /*422 * Use firmware provided latency values423 * starting with POWER10 platforms. In the424 * case that we are running on a POWER10425 * platform but in an earlier compat mode, we426 * can still use the firmware provided values.427 *428 * However, on platforms prior to POWER10, we429 * cannot rely on the accuracy of the firmware430 * provided latency values. On such platforms,431 * go with the conservative default estimate432 * of 10us.433 */434 if (cpu_has_feature(CPU_FTR_ARCH_31) || pvr_version_is(PVR_POWER10))435 fixup_cede0_latency();436 cpuidle_state_table = dedicated_states;437 max_idle_state = NR_DEDICATED_STATES;438 }439 } else440 return -ENODEV;441 442 if (max_idle_state > 1) {443 snooze_timeout_en = true;444 snooze_timeout = cpuidle_state_table[1].target_residency *445 tb_ticks_per_usec;446 }447 return 0;448}449 450static int __init pseries_processor_idle_init(void)451{452 int retval;453 454 retval = pseries_idle_probe();455 if (retval)456 return retval;457 458 pseries_cpuidle_driver_init();459 retval = cpuidle_register(&pseries_idle_driver, NULL);460 if (retval) {461 printk(KERN_DEBUG "Registration of pseries driver failed.\n");462 return retval;463 }464 465 retval = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,466 "cpuidle/pseries:online",467 pseries_cpuidle_cpu_online, NULL);468 WARN_ON(retval < 0);469 retval = cpuhp_setup_state_nocalls(CPUHP_CPUIDLE_DEAD,470 "cpuidle/pseries:DEAD", NULL,471 pseries_cpuidle_cpu_dead);472 WARN_ON(retval < 0);473 printk(KERN_DEBUG "pseries_idle_driver registered\n");474 return 0;475}476 477device_initcall(pseries_processor_idle_init);478