/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright IBM Corp. 2008
 *
 * Authors: Hollis Blanchard <hollisb@us.ibm.com>
 *          Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
 */

#include <linux/kvm_host.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>

#include <asm/time.h>
#include <asm-generic/div64.h>

#include "timing.h"

void kvmppc_init_timing_stats(struct kvm_vcpu *vcpu)
{
        int i;

        /* pause guest execution to avoid concurrent updates */
        local_irq_disable();
        mutex_lock(&vcpu->mutex);

        vcpu->arch.last_exit_type = 0xDEAD;
        for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {
                vcpu->arch.timing_count_type[i] = 0;
                vcpu->arch.timing_max_duration[i] = 0;
                vcpu->arch.timing_min_duration[i] = 0xFFFFFFFF;
                vcpu->arch.timing_sum_duration[i] = 0;
                vcpu->arch.timing_sum_quad_duration[i] = 0;
        }
        vcpu->arch.timing_last_exit = 0;
        vcpu->arch.timing_exit.tv64 = 0;
        vcpu->arch.timing_last_enter.tv64 = 0;

        mutex_unlock(&vcpu->mutex);
        local_irq_enable();
}

static void add_exit_timing(struct kvm_vcpu *vcpu, u64 duration, int type)
{
        u64 old;

        do_div(duration, tb_ticks_per_usec);
        if (unlikely(duration > 0xFFFFFFFF)) {
                printk(KERN_ERR"%s - duration too big -> overflow"
                        " duration %lld type %d exit #%d\n",
                        __func__, duration, type,
                        vcpu->arch.timing_count_type[type]);
                return;
        }

        vcpu->arch.timing_count_type[type]++;

        /* sum */
        old = vcpu->arch.timing_sum_duration[type];
        vcpu->arch.timing_sum_duration[type] += duration;
        if (unlikely(old > vcpu->arch.timing_sum_duration[type])) {
                printk(KERN_ERR"%s - wrap adding sum of durations"
                        " old %lld new %lld type %d exit # of type %d\n",
                        __func__, old, vcpu->arch.timing_sum_duration[type],
                        type, vcpu->arch.timing_count_type[type]);
        }

        /* square sum */
        old = vcpu->arch.timing_sum_quad_duration[type];
        vcpu->arch.timing_sum_quad_duration[type] += (duration*duration);
        if (unlikely(old > vcpu->arch.timing_sum_quad_duration[type])) {
                printk(KERN_ERR"%s - wrap adding sum of squared durations"
                        " old %lld new %lld type %d exit # of type %d\n",
                        __func__, old,
                        vcpu->arch.timing_sum_quad_duration[type],
                        type, vcpu->arch.timing_count_type[type]);
        }

        /* set min/max */
        if (unlikely(duration < vcpu->arch.timing_min_duration[type]))
                vcpu->arch.timing_min_duration[type] = duration;
        if (unlikely(duration > vcpu->arch.timing_max_duration[type]))
                vcpu->arch.timing_max_duration[type] = duration;
}

void kvmppc_update_timing_stats(struct kvm_vcpu *vcpu)
{
        u64 exit = vcpu->arch.timing_last_exit;
        u64 enter = vcpu->arch.timing_last_enter.tv64;

        /* save exit time, used next exit when the reenter time is known */
        vcpu->arch.timing_last_exit = vcpu->arch.timing_exit.tv64;

        if (unlikely(vcpu->arch.last_exit_type == 0xDEAD || exit == 0))
                return; /* skip incomplete cycle (e.g. after reset) */

        /* update statistics for average and standard deviation */
        add_exit_timing(vcpu, (enter - exit), vcpu->arch.last_exit_type);
        /* enter -> timing_last_exit is time spent in guest - log this too */
        add_exit_timing(vcpu, (vcpu->arch.timing_last_exit - enter),
                        TIMEINGUEST);
}

static const char *kvm_exit_names[__NUMBER_OF_KVM_EXIT_TYPES] = {
        [MMIO_EXITS] =              "MMIO",
        [DCR_EXITS] =               "DCR",
        [SIGNAL_EXITS] =            "SIGNAL",
        [ITLB_REAL_MISS_EXITS] =    "ITLBREAL",
        [ITLB_VIRT_MISS_EXITS] =    "ITLBVIRT",
        [DTLB_REAL_MISS_EXITS] =    "DTLBREAL",
        [DTLB_VIRT_MISS_EXITS] =    "DTLBVIRT",
        [SYSCALL_EXITS] =           "SYSCALL",
        [ISI_EXITS] =               "ISI",
        [DSI_EXITS] =               "DSI",
        [EMULATED_INST_EXITS] =     "EMULINST",
        [EMULATED_MTMSRWE_EXITS] =  "EMUL_WAIT",
        [EMULATED_WRTEE_EXITS] =    "EMUL_WRTEE",
        [EMULATED_MTSPR_EXITS] =    "EMUL_MTSPR",
        [EMULATED_MFSPR_EXITS] =    "EMUL_MFSPR",
        [EMULATED_MTMSR_EXITS] =    "EMUL_MTMSR",
        [EMULATED_MFMSR_EXITS] =    "EMUL_MFMSR",
        [EMULATED_TLBSX_EXITS] =    "EMUL_TLBSX",
        [EMULATED_TLBWE_EXITS] =    "EMUL_TLBWE",
        [EMULATED_RFI_EXITS] =      "EMUL_RFI",
        [DEC_EXITS] =               "DEC",
        [EXT_INTR_EXITS] =          "EXTINT",
        [HALT_WAKEUP] =             "HALT",
        [USR_PR_INST] =             "USR_PR_INST",
        [FP_UNAVAIL] =              "FP_UNAVAIL",
        [DEBUG_EXITS] =             "DEBUG",
        [TIMEINGUEST] =             "TIMEINGUEST"
};

static int kvmppc_exit_timing_show(struct seq_file *m, void *private)
{
        struct kvm_vcpu *vcpu = m->private;
        int i;

        seq_printf(m, "%s", "type       count   min     max     sum     sum_squared\n");

        for (i = 0; i < __NUMBER_OF_KVM_EXIT_TYPES; i++) {
                seq_printf(m, "%12s     %10d    %10lld  %10lld  %20lld  %20lld\n",
                        kvm_exit_names[i],
                        vcpu->arch.timing_count_type[i],
                        vcpu->arch.timing_min_duration[i],
                        vcpu->arch.timing_max_duration[i],
                        vcpu->arch.timing_sum_duration[i],
                        vcpu->arch.timing_sum_quad_duration[i]);
        }
        return 0;
}

/* Write 'c' to clear the timing statistics. */
static ssize_t kvmppc_exit_timing_write(struct file *file,
                                       const char __user *user_buf,
                                       size_t count, loff_t *ppos)
{
        int err = -EINVAL;
        char c;

        if (count > 1) {
                goto done;
        }

        if (get_user(c, user_buf)) {
                err = -EFAULT;
                goto done;
        }

        if (c == 'c') {
                struct seq_file *seqf = (struct seq_file *)file->private_data;
                struct kvm_vcpu *vcpu = seqf->private;
                /* Write does not affect our buffers previously generated with
                 * show. seq_file is locked here to prevent races of init with
                 * a show call */
                mutex_lock(&seqf->lock);
                kvmppc_init_timing_stats(vcpu);
                mutex_unlock(&seqf->lock);
                err = count;
        }

done:
        return err;
}

static int kvmppc_exit_timing_open(struct inode *inode, struct file *file)
{
        return single_open(file, kvmppc_exit_timing_show, inode->i_private);
}

static const struct file_operations kvmppc_exit_timing_fops = {
        .owner   = THIS_MODULE,
        .open    = kvmppc_exit_timing_open,
        .read    = seq_read,
        .write   = kvmppc_exit_timing_write,
        .llseek  = seq_lseek,
        .release = single_release,
};

void kvmppc_create_vcpu_debugfs(struct kvm_vcpu *vcpu, unsigned int id)
{
        static char dbg_fname[50];
        struct dentry *debugfs_file;

        snprintf(dbg_fname, sizeof(dbg_fname), "vm%u_vcpu%u_timing",
                 current->pid, id);
        debugfs_file = debugfs_create_file(dbg_fname, 0666,
                                        kvm_debugfs_dir, vcpu,
                                        &kvmppc_exit_timing_fops);

        if (!debugfs_file) {
                printk(KERN_ERR"%s: error creating debugfs file %s\n",
                        __func__, dbg_fname);
                return;
        }

        vcpu->arch.debugfs_exit_timing = debugfs_file;
}

void kvmppc_remove_vcpu_debugfs(struct kvm_vcpu *vcpu)
{
        if (vcpu->arch.debugfs_exit_timing) {
                debugfs_remove(vcpu->arch.debugfs_exit_timing);
                vcpu->arch.debugfs_exit_timing = NULL;
        }
}