linux-imx

/*

 * Virtual PTP 1588 clock for use with KVM guests

 *

 * Copyright (C) 2017 Red Hat Inc.

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  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.

 *

 */

#include <linux/device.h>

#include <linux/err.h>

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <uapi/linux/kvm_para.h>

#include <asm/kvm_para.h>

#include <asm/pvclock.h>

#include <asm/kvmclock.h>

#include <uapi/asm/kvm_para.h>

​

#include <linux/ptp_clock_kernel.h>

​

struct kvm_ptp_clock {

    struct ptp_clock *ptp_clock;

    struct ptp_clock_info caps;

};

​

DEFINE_SPINLOCK(kvm_ptp_lock);

​

static struct pvclock_vsyscall_time_info *hv_clock;

​

static struct kvm_clock_pairing clock_pair;

static phys_addr_t clock_pair_gpa;

​

static int ptp_kvm_get_time_fn(ktime_t *device_time,

                   struct system_counterval_t *system_counter,

                   void *ctx)

{

    unsigned long ret;

    struct timespec64 tspec;

    unsigned version;

    int cpu;

    struct pvclock_vcpu_time_info *src;

​

    spin_lock(&kvm_ptp_lock);

​

    preempt_disable_notrace();

    cpu = smp_processor_id();

    src = &hv_clock[cpu].pvti;

​

    do {

        /*

         * We are using a TSC value read in the hosts

         * kvm_hc_clock_pairing handling.

         * So any changes to tsc_to_system_mul

         * and tsc_shift or any other pvclock

         * data invalidate that measurement.

         */

        version = pvclock_read_begin(src);

​

        ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,

                     clock_pair_gpa,

                     KVM_CLOCK_PAIRING_WALLCLOCK);

        if (ret != 0) {

            pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);

            spin_unlock(&kvm_ptp_lock);

            preempt_enable_notrace();

            return -EOPNOTSUPP;

        }

​

        tspec.tv_sec = clock_pair.sec;

        tspec.tv_nsec = clock_pair.nsec;

        ret = __pvclock_read_cycles(src, clock_pair.tsc);

    } while (pvclock_read_retry(src, version));

​

    preempt_enable_notrace();

​

    system_counter->cycles = ret;

    system_counter->cs = &kvm_clock;

​

    *device_time = timespec64_to_ktime(tspec);

​

    spin_unlock(&kvm_ptp_lock);

​

    return 0;