linux/arch/powerpc/kvm/timing.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *
   4 * Copyright IBM Corp. 2008
   5 *
   6 * Authors: Hollis Blanchard <hollisb@us.ibm.com>
   7 *          Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
   8 */
   9
  10#include <linux/kvm_host.h>
  11#include <linux/fs.h>
  12#include <linux/seq_file.h>
  13#include <linux/debugfs.h>
  14#include <linux/uaccess.h>
  15#include <linux/module.h>
  16
  17#include <asm/time.h>
  18#include <asm-generic/div64.h>
  19
  20#include "timing.h"
  21
  22void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu)
  23{
  24        int i;
  25
  26        /* Take a lock to avoid concurrent updates */
  27        mutex_lock(&vcpu->arch.exit_timing_lock);
  28
  29        vcpu->arch.last_exit_type = 0xDEAD;
  30        for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {
  31                vcpu->arch.timing_count_type[i] = 0;
  32                vcpu->arch.timing_max_duration[i] = 0;
  33                vcpu->arch.timing_min_duration[i] = 0xFFFFFFFF;
  34                vcpu->arch.timing_sum_duration[i] = 0;
  35                vcpu->arch.timing_sum_quad_duration[i] = 0;
  36        }
  37        vcpu->arch.timing_last_exit = 0;
  38        vcpu->arch.timing_exit.tv64 = 0;
  39        vcpu->arch.timing_last_enter.tv64 = 0;
  40
  41        mutex_unlock(&vcpu->arch.exit_timing_lock);
  42}
  43
  44static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type)
  45{
  46        u64 old;
  47
  48        mutex_lock(&vcpu->arch.exit_timing_lock);
  49
  50        vcpu->arch.timing_count_type[type]++;
  51
  52        /* sum */
  53        old = vcpu->arch.timing_sum_duration[type];
  54        vcpu->arch.timing_sum_duration[type] += duration;
  55        if (unlikely(old > vcpu->arch.timing_sum_duration[type])) {
  56                printk(KERN_ERR"%s - wrap adding sum of durations"
  57                        " old %lld new %lld type %d exit # of type %d\n",
  58                        __func__, old, vcpu->arch.timing_sum_duration[type],
  59                        type, vcpu->arch.timing_count_type[type]);
  60        }
  61
  62        /* square sum */
  63        old = vcpu->arch.timing_sum_quad_duration[type];
  64        vcpu->arch.timing_sum_quad_duration[type] += (duration*duration);
  65        if (unlikely(old > vcpu->arch.timing_sum_quad_duration[type])) {
  66                printk(KERN_ERR"%s - wrap adding sum of squared durations"
  67                        " old %lld new %lld type %d exit # of type %d\n",
  68                        __func__, old,
  69                        vcpu->arch.timing_sum_quad_duration[type],
  70                        type, vcpu->arch.timing_count_type[type]);
  71        }
  72
  73        /* set min/max */
  74        if (unlikely(duration < vcpu->arch.timing_min_duration[type]))
  75                vcpu->arch.timing_min_duration[type] = duration;
  76        if (unlikely(duration > vcpu->arch.timing_max_duration[type]))
  77                vcpu->arch.timing_max_duration[type] = duration;
  78
  79        mutex_unlock(&vcpu->arch.exit_timing_lock);
  80}
  81
  82void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu)
  83{
  84        u64 exit = vcpu->arch.timing_last_exit;
  85        u64 enter = vcpu->arch.timing_last_enter.tv64;
  86
  87        /* save exit time, used next exit when the reenter time is known */
  88        vcpu->arch.timing_last_exit = vcpu->arch.timing_exit.tv64;
  89
  90        if (unlikely(vcpu->arch.last_exit_type == 0xDEAD || exit == 0))
  91                return; /* skip incomplete cycle (e.g. after reset) */
  92
  93        /* update statistics for average and standard deviation */
  94        add_exit_timing(vcpu, (enter - exit), vcpu->arch.last_exit_type);
  95        /* enter -> timing_last_exit is time spent in guest - log this too */
  96        add_exit_timing(vcpu, (vcpu->arch.timing_last_exit - enter),
  97                        TIMEINGUEST);
  98}
  99
 100static const char *kvm_exit_names[__NUMBER_OF_KVM_EXIT_TYPES] = {
 101        [MMIO_EXITS] =              "MMIO",
 102        [SIGNAL_EXITS] =            "SIGNAL",
 103        [ITLB_REAL_MISS_EXITS] =    "ITLBREAL",
 104        [ITLB_VIRT_MISS_EXITS] =    "ITLBVIRT",
 105        [DTLB_REAL_MISS_EXITS] =    "DTLBREAL",
 106        [DTLB_VIRT_MISS_EXITS] =    "DTLBVIRT",
 107        [SYSCALL_EXITS] =           "SYSCALL",
 108        [ISI_EXITS] =               "ISI",
 109        [DSI_EXITS] =               "DSI",
 110        [EMULATED_INST_EXITS] =     "EMULINST",
 111        [EMULATED_MTMSRWE_EXITS] =  "EMUL_WAIT",
 112        [EMULATED_WRTEE_EXITS] =    "EMUL_WRTEE",
 113        [EMULATED_MTSPR_EXITS] =    "EMUL_MTSPR",
 114        [EMULATED_MFSPR_EXITS] =    "EMUL_MFSPR",
 115        [EMULATED_MTMSR_EXITS] =    "EMUL_MTMSR",
 116        [EMULATED_MFMSR_EXITS] =    "EMUL_MFMSR",
 117        [EMULATED_TLBSX_EXITS] =    "EMUL_TLBSX",
 118        [EMULATED_TLBWE_EXITS] =    "EMUL_TLBWE",
 119        [EMULATED_RFI_EXITS] =      "EMUL_RFI",
 120        [DEC_EXITS] =               "DEC",
 121        [EXT_INTR_EXITS] =          "EXTINT",
 122        [HALT_WAKEUP] =             "HALT",
 123        [USR_PR_INST] =             "USR_PR_INST",
 124        [FP_UNAVAIL] =              "FP_UNAVAIL",
 125        [DEBUG_EXITS] =             "DEBUG",
 126        [TIMEINGUEST] =             "TIMEINGUEST"
 127};
 128
 129static int kvmppc_exit_timing_show(struct seq_file *m, void *private)
 130{
 131        struct kvm_vcpu *vcpu = m->private;
 132        int i;
 133        u64 min, max, sum, sum_quad;
 134
 135        seq_puts(m, "type       count   min     max     sum     sum_squared\n");
 136
 137        for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {
 138
 139                min = vcpu->arch.timing_min_duration[i];
 140                do_div(min, tb_ticks_per_usec);
 141                max = vcpu->arch.timing_max_duration[i];
 142                do_div(max, tb_ticks_per_usec);
 143                sum = vcpu->arch.timing_sum_duration[i];
 144                do_div(sum, tb_ticks_per_usec);
 145                sum_quad = vcpu->arch.timing_sum_quad_duration[i];
 146                do_div(sum_quad, tb_ticks_per_usec);
 147
 148                seq_printf(m, "%12s     %10d    %10lld  %10lld  %20lld  %20lld\n",
 149                        kvm_exit_names[i],
 150                        vcpu->arch.timing_count_type[i],
 151                        min,
 152                        max,
 153                        sum,
 154                        sum_quad);
 155
 156        }
 157        return 0;
 158}
 159
 160/* Write 'c' to clear the timing statistics. */
 161static ssize_t kvmppc_exit_timing_write(struct file *file,
 162                                       const char __user *user_buf,
 163                                       size_t count, loff_t *ppos)
 164{
 165        int err = -EINVAL;
 166        char c;
 167
 168        if (count > 1) {
 169                goto done;
 170        }
 171
 172        if (get_user(c, user_buf)) {
 173                err = -EFAULT;
 174                goto done;
 175        }
 176
 177        if (c == 'c') {
 178                struct seq_file *seqf = file->private_data;
 179                struct kvm_vcpu *vcpu = seqf->private;
 180                /* Write does not affect our buffers previously generated with
 181                 * show. seq_file is locked here to prevent races of init with
 182                 * a show call */
 183                mutex_lock(&seqf->lock);
 184                kvmppc_init_timing_stats(vcpu);
 185                mutex_unlock(&seqf->lock);
 186                err = count;
 187        }
 188
 189done:
 190        return err;
 191}
 192
 193static int kvmppc_exit_timing_open(struct inode *inode, struct file *file)
 194{
 195        return single_open(file, kvmppc_exit_timing_show, inode->i_private);
 196}
 197
 198static const struct file_operations kvmppc_exit_timing_fops = {
 199        .owner   = THIS_MODULE,
 200        .open    = kvmppc_exit_timing_open,
 201        .read    = seq_read,
 202        .write   = kvmppc_exit_timing_write,
 203        .llseek  = seq_lseek,
 204        .release = single_release,
 205};
 206
 207void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id)
 208{
 209        static char dbg_fname[50];
 210        struct dentry *debugfs_file;
 211
 212        snprintf(dbg_fname, sizeof(dbg_fname), "vm%u_vcpu%u_timing",
 213                 current->pid, id);
 214        debugfs_file = debugfs_create_file(dbg_fname, 0666, kvm_debugfs_dir,
 215                                                vcpu, &kvmppc_exit_timing_fops);
 216
 217        vcpu->arch.debugfs_exit_timing = debugfs_file;
 218}
 219
 220void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu)
 221{
 222        debugfs_remove(vcpu->arch.debugfs_exit_timing);
 223        vcpu->arch.debugfs_exit_timing = NULL;
 224}
 225