powerpc/kvm/timing.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *
0004  * Copyright IBM Corp. 2008
0005  *
0006  * Authors: Hollis Blanchard <hollisb@us.ibm.com>
0007  *          Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
0008  */
0009
0010 #include <linux/kvm_host.h>
0011 #include <linux/fs.h>
0012 #include <linux/seq_file.h>
0013 #include <linux/debugfs.h>
0014 #include <linux/uaccess.h>
0015 #include <linux/module.h>
0016
0017 #include <asm/time.h>
0018 #include <asm-generic/div64.h>
0019
0020 #include "timing.h"
0021
0022 void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu)
0023 {
0024     int i;
0025
0026     /* Take a lock to avoid concurrent updates */
0027     mutex_lock(&vcpu->arch.exit_timing_lock);
0028
0029     vcpu->arch.last_exit_type = 0xDEAD;
0030     for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {
0031         vcpu->arch.timing_count_type[i] = 0;
0032         vcpu->arch.timing_max_duration[i] = 0;
0033         vcpu->arch.timing_min_duration[i] = 0xFFFFFFFF;
0034         vcpu->arch.timing_sum_duration[i] = 0;
0035         vcpu->arch.timing_sum_quad_duration[i] = 0;
0036     }
0037     vcpu->arch.timing_last_exit = 0;
0038     vcpu->arch.timing_exit.tv64 = 0;
0039     vcpu->arch.timing_last_enter.tv64 = 0;
0040
0041     mutex_unlock(&vcpu->arch.exit_timing_lock);
0042 }
0043
0044 static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type)
0045 {
0046     u64 old;
0047
0048     mutex_lock(&vcpu->arch.exit_timing_lock);
0049
0050     vcpu->arch.timing_count_type[type]++;
0051
0052     /* sum */
0053     old = vcpu->arch.timing_sum_duration[type];
0054     vcpu->arch.timing_sum_duration[type] += duration;
0055     if (unlikely(old > vcpu->arch.timing_sum_duration[type])) {
0056         printk(KERN_ERR"%s - wrap adding sum of durations"
0057             " old %lld new %lld type %d exit # of type %d\n",
0058             __func__, old, vcpu->arch.timing_sum_duration[type],
0059             type, vcpu->arch.timing_count_type[type]);
0060     }
0061
0062     /* square sum */
0063     old = vcpu->arch.timing_sum_quad_duration[type];
0064     vcpu->arch.timing_sum_quad_duration[type] += (duration*duration);
0065     if (unlikely(old > vcpu->arch.timing_sum_quad_duration[type])) {
0066         printk(KERN_ERR"%s - wrap adding sum of squared durations"
0067             " old %lld new %lld type %d exit # of type %d\n",
0068             __func__, old,
0069             vcpu->arch.timing_sum_quad_duration[type],
0070             type, vcpu->arch.timing_count_type[type]);
0071     }
0072
0073     /* set min/max */
0074     if (unlikely(duration < vcpu->arch.timing_min_duration[type]))
0075         vcpu->arch.timing_min_duration[type] = duration;
0076     if (unlikely(duration > vcpu->arch.timing_max_duration[type]))
0077         vcpu->arch.timing_max_duration[type] = duration;
0078
0079     mutex_unlock(&vcpu->arch.exit_timing_lock);
0080 }
0081
0082 void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu)
0083 {
0084     u64 exit = vcpu->arch.timing_last_exit;
0085     u64 enter = vcpu->arch.timing_last_enter.tv64;
0086
0087     /* save exit time, used next exit when the reenter time is known */
0088     vcpu->arch.timing_last_exit = vcpu->arch.timing_exit.tv64;
0089
0090     if (unlikely(vcpu->arch.last_exit_type == 0xDEAD || exit == 0))
0091         return; /* skip incomplete cycle (e.g. after reset) */
0092
0093     /* update statistics for average and standard deviation */
0094     add_exit_timing(vcpu, (enter - exit), vcpu->arch.last_exit_type);
0095     /* enter -> timing_last_exit is time spent in guest - log this too */
0096     add_exit_timing(vcpu, (vcpu->arch.timing_last_exit - enter),
0097             TIMEINGUEST);
0098 }
0099
0100 static const char *kvm_exit_names[__NUMBER_OF_KVM_EXIT_TYPES] = {
0101     [MMIO_EXITS] =              "MMIO",
0102     [SIGNAL_EXITS] =            "SIGNAL",
0103     [ITLB_REAL_MISS_EXITS] =    "ITLBREAL",
0104     [ITLB_VIRT_MISS_EXITS] =    "ITLBVIRT",
0105     [DTLB_REAL_MISS_EXITS] =    "DTLBREAL",
0106     [DTLB_VIRT_MISS_EXITS] =    "DTLBVIRT",
0107     [SYSCALL_EXITS] =           "SYSCALL",
0108     [ISI_EXITS] =               "ISI",
0109     [DSI_EXITS] =               "DSI",
0110     [EMULATED_INST_EXITS] =     "EMULINST",
0111     [EMULATED_MTMSRWE_EXITS] =  "EMUL_WAIT",
0112     [EMULATED_WRTEE_EXITS] =    "EMUL_WRTEE",
0113     [EMULATED_MTSPR_EXITS] =    "EMUL_MTSPR",
0114     [EMULATED_MFSPR_EXITS] =    "EMUL_MFSPR",
0115     [EMULATED_MTMSR_EXITS] =    "EMUL_MTMSR",
0116     [EMULATED_MFMSR_EXITS] =    "EMUL_MFMSR",
0117     [EMULATED_TLBSX_EXITS] =    "EMUL_TLBSX",
0118     [EMULATED_TLBWE_EXITS] =    "EMUL_TLBWE",
0119     [EMULATED_RFI_EXITS] =      "EMUL_RFI",
0120     [DEC_EXITS] =               "DEC",
0121     [EXT_INTR_EXITS] =          "EXTINT",
0122     [HALT_WAKEUP] =             "HALT",
0123     [USR_PR_INST] =             "USR_PR_INST",
0124     [FP_UNAVAIL] =              "FP_UNAVAIL",
0125     [DEBUG_EXITS] =             "DEBUG",
0126     [TIMEINGUEST] =             "TIMEINGUEST"
0127 };
0128
0129 static int kvmppc_exit_timing_show(struct seq_file *m, void *private)
0130 {
0131     struct kvm_vcpu *vcpu = m->private;
0132     int i;
0133     u64 min, max, sum, sum_quad;
0134
0135     seq_puts(m, "type   count   min max sum sum_squared\n");
0136
0137     for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {
0138
0139         min = vcpu->arch.timing_min_duration[i];
0140         do_div(min, tb_ticks_per_usec);
0141         max = vcpu->arch.timing_max_duration[i];
0142         do_div(max, tb_ticks_per_usec);
0143         sum = vcpu->arch.timing_sum_duration[i];
0144         do_div(sum, tb_ticks_per_usec);
0145         sum_quad = vcpu->arch.timing_sum_quad_duration[i];
0146         do_div(sum_quad, tb_ticks_per_usec);
0147
0148         seq_printf(m, "%12s %10d    %10lld  %10lld  %20lld  %20lld\n",
0149             kvm_exit_names[i],
0150             vcpu->arch.timing_count_type[i],
0151             min,
0152             max,
0153             sum,
0154             sum_quad);
0155
0156     }
0157     return 0;
0158 }
0159
0160 /* Write 'c' to clear the timing statistics. */
0161 static ssize_t kvmppc_exit_timing_write(struct file *file,
0162                        const char __user *user_buf,
0163                        size_t count, loff_t *ppos)
0164 {
0165     int err = -EINVAL;
0166     char c;
0167
0168     if (count > 1) {
0169         goto done;
0170     }
0171
0172     if (get_user(c, user_buf)) {
0173         err = -EFAULT;
0174         goto done;
0175     }
0176
0177     if (c == 'c') {
0178         struct seq_file *seqf = file->private_data;
0179         struct kvm_vcpu *vcpu = seqf->private;
0180         /* Write does not affect our buffers previously generated with
0181          * show. seq_file is locked here to prevent races of init with
0182          * a show call */
0183         mutex_lock(&seqf->lock);
0184         kvmppc_init_timing_stats(vcpu);
0185         mutex_unlock(&seqf->lock);
0186         err = count;
0187     }
0188
0189 done:
0190     return err;
0191 }
0192
0193 static int kvmppc_exit_timing_open(struct inode *inode, struct file *file)
0194 {
0195     return single_open(file, kvmppc_exit_timing_show, inode->i_private);
0196 }
0197
0198 static const struct file_operations kvmppc_exit_timing_fops = {
0199     .owner   = THIS_MODULE,
0200     .open    = kvmppc_exit_timing_open,
0201     .read    = seq_read,
0202     .write   = kvmppc_exit_timing_write,
0203     .llseek  = seq_lseek,
0204     .release = single_release,
0205 };
0206
0207 int kvmppc_create_vcpu_debugfs_e500(struct kvm_vcpu *vcpu,
0208                     struct dentry *debugfs_dentry)
0209 {
0210     debugfs_create_file("timing", 0666, debugfs_dentry,
0211                 vcpu, &kvmppc_exit_timing_fops);
0212     return 0;
0213 }