linux/arch/powerpc/perf/hv-gpci.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Hypervisor supplied "gpci" ("get performance counter info") performance
   4 * counter support
   5 *
   6 * Author: Cody P Schafer <cody@linux.vnet.ibm.com>
   7 * Copyright 2014 IBM Corporation.
   8 */
   9
  10#define pr_fmt(fmt) "hv-gpci: " fmt
  11
  12#include <linux/init.h>
  13#include <linux/perf_event.h>
  14#include <asm/firmware.h>
  15#include <asm/hvcall.h>
  16#include <asm/io.h>
  17
  18#include "hv-gpci.h"
  19#include "hv-common.h"
  20
  21/*
  22 * Example usage:
  23 *  perf stat -e 'hv_gpci/counter_info_version=3,offset=0,length=8,
  24 *                secondary_index=0,starting_index=0xffffffff,request=0x10/' ...
  25 */
  26
  27/* u32 */
  28EVENT_DEFINE_RANGE_FORMAT(request, config, 0, 31);
  29/* u32 */
  30/*
  31 * Note that starting_index, phys_processor_idx, sibling_part_id,
  32 * hw_chip_id, partition_id all refer to the same bit range. They
  33 * are basically aliases for the starting_index. The specific alias
  34 * used depends on the event. See REQUEST_IDX_KIND in hv-gpci-requests.h
  35 */
  36EVENT_DEFINE_RANGE_FORMAT(starting_index, config, 32, 63);
  37EVENT_DEFINE_RANGE_FORMAT_LITE(phys_processor_idx, config, 32, 63);
  38EVENT_DEFINE_RANGE_FORMAT_LITE(sibling_part_id, config, 32, 63);
  39EVENT_DEFINE_RANGE_FORMAT_LITE(hw_chip_id, config, 32, 63);
  40EVENT_DEFINE_RANGE_FORMAT_LITE(partition_id, config, 32, 63);
  41
  42/* u16 */
  43EVENT_DEFINE_RANGE_FORMAT(secondary_index, config1, 0, 15);
  44/* u8 */
  45EVENT_DEFINE_RANGE_FORMAT(counter_info_version, config1, 16, 23);
  46/* u8, bytes of data (1-8) */
  47EVENT_DEFINE_RANGE_FORMAT(length, config1, 24, 31);
  48/* u32, byte offset */
  49EVENT_DEFINE_RANGE_FORMAT(offset, config1, 32, 63);
  50
  51static cpumask_t hv_gpci_cpumask;
  52
  53static struct attribute *format_attrs[] = {
  54        &format_attr_request.attr,
  55        &format_attr_starting_index.attr,
  56        &format_attr_phys_processor_idx.attr,
  57        &format_attr_sibling_part_id.attr,
  58        &format_attr_hw_chip_id.attr,
  59        &format_attr_partition_id.attr,
  60        &format_attr_secondary_index.attr,
  61        &format_attr_counter_info_version.attr,
  62
  63        &format_attr_offset.attr,
  64        &format_attr_length.attr,
  65        NULL,
  66};
  67
  68static struct attribute_group format_group = {
  69        .name = "format",
  70        .attrs = format_attrs,
  71};
  72
  73static struct attribute_group event_group = {
  74        .name  = "events",
  75        .attrs = hv_gpci_event_attrs,
  76};
  77
  78#define HV_CAPS_ATTR(_name, _format)                            \
  79static ssize_t _name##_show(struct device *dev,                 \
  80                            struct device_attribute *attr,      \
  81                            char *page)                         \
  82{                                                               \
  83        struct hv_perf_caps caps;                               \
  84        unsigned long hret = hv_perf_caps_get(&caps);           \
  85        if (hret)                                               \
  86                return -EIO;                                    \
  87                                                                \
  88        return sprintf(page, _format, caps._name);              \
  89}                                                               \
  90static struct device_attribute hv_caps_attr_##_name = __ATTR_RO(_name)
  91
  92static ssize_t kernel_version_show(struct device *dev,
  93                                   struct device_attribute *attr,
  94                                   char *page)
  95{
  96        return sprintf(page, "0x%x\n", COUNTER_INFO_VERSION_CURRENT);
  97}
  98
  99static ssize_t cpumask_show(struct device *dev,
 100                            struct device_attribute *attr, char *buf)
 101{
 102        return cpumap_print_to_pagebuf(true, buf, &hv_gpci_cpumask);
 103}
 104
 105static DEVICE_ATTR_RO(kernel_version);
 106static DEVICE_ATTR_RO(cpumask);
 107
 108HV_CAPS_ATTR(version, "0x%x\n");
 109HV_CAPS_ATTR(ga, "%d\n");
 110HV_CAPS_ATTR(expanded, "%d\n");
 111HV_CAPS_ATTR(lab, "%d\n");
 112HV_CAPS_ATTR(collect_privileged, "%d\n");
 113
 114static struct attribute *interface_attrs[] = {
 115        &dev_attr_kernel_version.attr,
 116        &hv_caps_attr_version.attr,
 117        &hv_caps_attr_ga.attr,
 118        &hv_caps_attr_expanded.attr,
 119        &hv_caps_attr_lab.attr,
 120        &hv_caps_attr_collect_privileged.attr,
 121        NULL,
 122};
 123
 124static struct attribute *cpumask_attrs[] = {
 125        &dev_attr_cpumask.attr,
 126        NULL,
 127};
 128
 129static struct attribute_group cpumask_attr_group = {
 130        .attrs = cpumask_attrs,
 131};
 132
 133static struct attribute_group interface_group = {
 134        .name = "interface",
 135        .attrs = interface_attrs,
 136};
 137
 138static const struct attribute_group *attr_groups[] = {
 139        &format_group,
 140        &event_group,
 141        &interface_group,
 142        &cpumask_attr_group,
 143        NULL,
 144};
 145
 146static DEFINE_PER_CPU(char, hv_gpci_reqb[HGPCI_REQ_BUFFER_SIZE]) __aligned(sizeof(uint64_t));
 147
 148static unsigned long single_gpci_request(u32 req, u32 starting_index,
 149                u16 secondary_index, u8 version_in, u32 offset, u8 length,
 150                u64 *value)
 151{
 152        unsigned long ret;
 153        size_t i;
 154        u64 count;
 155        struct hv_gpci_request_buffer *arg;
 156
 157        arg = (void *)get_cpu_var(hv_gpci_reqb);
 158        memset(arg, 0, HGPCI_REQ_BUFFER_SIZE);
 159
 160        arg->params.counter_request = cpu_to_be32(req);
 161        arg->params.starting_index = cpu_to_be32(starting_index);
 162        arg->params.secondary_index = cpu_to_be16(secondary_index);
 163        arg->params.counter_info_version_in = version_in;
 164
 165        ret = plpar_hcall_norets(H_GET_PERF_COUNTER_INFO,
 166                        virt_to_phys(arg), HGPCI_REQ_BUFFER_SIZE);
 167        if (ret) {
 168                pr_devel("hcall failed: 0x%lx\n", ret);
 169                goto out;
 170        }
 171
 172        /*
 173         * we verify offset and length are within the zeroed buffer at event
 174         * init.
 175         */
 176        count = 0;
 177        for (i = offset; i < offset + length; i++)
 178                count |= arg->bytes[i] << (i - offset);
 179
 180        *value = count;
 181out:
 182        put_cpu_var(hv_gpci_reqb);
 183        return ret;
 184}
 185
 186static u64 h_gpci_get_value(struct perf_event *event)
 187{
 188        u64 count;
 189        unsigned long ret = single_gpci_request(event_get_request(event),
 190                                        event_get_starting_index(event),
 191                                        event_get_secondary_index(event),
 192                                        event_get_counter_info_version(event),
 193                                        event_get_offset(event),
 194                                        event_get_length(event),
 195                                        &count);
 196        if (ret)
 197                return 0;
 198        return count;
 199}
 200
 201static void h_gpci_event_update(struct perf_event *event)
 202{
 203        s64 prev;
 204        u64 now = h_gpci_get_value(event);
 205        prev = local64_xchg(&event->hw.prev_count, now);
 206        local64_add(now - prev, &event->count);
 207}
 208
 209static void h_gpci_event_start(struct perf_event *event, int flags)
 210{
 211        local64_set(&event->hw.prev_count, h_gpci_get_value(event));
 212}
 213
 214static void h_gpci_event_stop(struct perf_event *event, int flags)
 215{
 216        h_gpci_event_update(event);
 217}
 218
 219static int h_gpci_event_add(struct perf_event *event, int flags)
 220{
 221        if (flags & PERF_EF_START)
 222                h_gpci_event_start(event, flags);
 223
 224        return 0;
 225}
 226
 227static int h_gpci_event_init(struct perf_event *event)
 228{
 229        u64 count;
 230        u8 length;
 231
 232        /* Not our event */
 233        if (event->attr.type != event->pmu->type)
 234                return -ENOENT;
 235
 236        /* config2 is unused */
 237        if (event->attr.config2) {
 238                pr_devel("config2 set when reserved\n");
 239                return -EINVAL;
 240        }
 241
 242        /* no branch sampling */
 243        if (has_branch_stack(event))
 244                return -EOPNOTSUPP;
 245
 246        length = event_get_length(event);
 247        if (length < 1 || length > 8) {
 248                pr_devel("length invalid\n");
 249                return -EINVAL;
 250        }
 251
 252        /* last byte within the buffer? */
 253        if ((event_get_offset(event) + length) > HGPCI_MAX_DATA_BYTES) {
 254                pr_devel("request outside of buffer: %zu > %zu\n",
 255                                (size_t)event_get_offset(event) + length,
 256                                HGPCI_MAX_DATA_BYTES);
 257                return -EINVAL;
 258        }
 259
 260        /* check if the request works... */
 261        if (single_gpci_request(event_get_request(event),
 262                                event_get_starting_index(event),
 263                                event_get_secondary_index(event),
 264                                event_get_counter_info_version(event),
 265                                event_get_offset(event),
 266                                length,
 267                                &count)) {
 268                pr_devel("gpci hcall failed\n");
 269                return -EINVAL;
 270        }
 271
 272        return 0;
 273}
 274
 275static struct pmu h_gpci_pmu = {
 276        .task_ctx_nr = perf_invalid_context,
 277
 278        .name = "hv_gpci",
 279        .attr_groups = attr_groups,
 280        .event_init  = h_gpci_event_init,
 281        .add         = h_gpci_event_add,
 282        .del         = h_gpci_event_stop,
 283        .start       = h_gpci_event_start,
 284        .stop        = h_gpci_event_stop,
 285        .read        = h_gpci_event_update,
 286        .capabilities = PERF_PMU_CAP_NO_EXCLUDE,
 287};
 288
 289static int ppc_hv_gpci_cpu_online(unsigned int cpu)
 290{
 291        if (cpumask_empty(&hv_gpci_cpumask))
 292                cpumask_set_cpu(cpu, &hv_gpci_cpumask);
 293
 294        return 0;
 295}
 296
 297static int ppc_hv_gpci_cpu_offline(unsigned int cpu)
 298{
 299        int target;
 300
 301        /* Check if exiting cpu is used for collecting gpci events */
 302        if (!cpumask_test_and_clear_cpu(cpu, &hv_gpci_cpumask))
 303                return 0;
 304
 305        /* Find a new cpu to collect gpci events */
 306        target = cpumask_last(cpu_active_mask);
 307
 308        if (target < 0 || target >= nr_cpu_ids) {
 309                pr_err("hv_gpci: CPU hotplug init failed\n");
 310                return -1;
 311        }
 312
 313        /* Migrate gpci events to the new target */
 314        cpumask_set_cpu(target, &hv_gpci_cpumask);
 315        perf_pmu_migrate_context(&h_gpci_pmu, cpu, target);
 316
 317        return 0;
 318}
 319
 320static int hv_gpci_cpu_hotplug_init(void)
 321{
 322        return cpuhp_setup_state(CPUHP_AP_PERF_POWERPC_HV_GPCI_ONLINE,
 323                          "perf/powerpc/hv_gcpi:online",
 324                          ppc_hv_gpci_cpu_online,
 325                          ppc_hv_gpci_cpu_offline);
 326}
 327
 328static int hv_gpci_init(void)
 329{
 330        int r;
 331        unsigned long hret;
 332        struct hv_perf_caps caps;
 333
 334        hv_gpci_assert_offsets_correct();
 335
 336        if (!firmware_has_feature(FW_FEATURE_LPAR)) {
 337                pr_debug("not a virtualized system, not enabling\n");
 338                return -ENODEV;
 339        }
 340
 341        hret = hv_perf_caps_get(&caps);
 342        if (hret) {
 343                pr_debug("could not obtain capabilities, not enabling, rc=%ld\n",
 344                                hret);
 345                return -ENODEV;
 346        }
 347
 348        /* init cpuhotplug */
 349        r = hv_gpci_cpu_hotplug_init();
 350        if (r)
 351                return r;
 352
 353        /* sampling not supported */
 354        h_gpci_pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
 355
 356        r = perf_pmu_register(&h_gpci_pmu, h_gpci_pmu.name, -1);
 357        if (r)
 358                return r;
 359
 360        return 0;
 361}
 362
 363device_initcall(hv_gpci_init);
 364