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197 lines
4.3 KiB
197 lines
4.3 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Virtual PTP 1588 clock for use with KVM guests |
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* |
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* Copyright (C) 2017 Red Hat Inc. |
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*/ |
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#include <linux/device.h> |
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#include <linux/err.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <uapi/linux/kvm_para.h> |
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#include <asm/kvm_para.h> |
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#include <asm/pvclock.h> |
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#include <asm/kvmclock.h> |
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#include <uapi/asm/kvm_para.h> |
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#include <linux/ptp_clock_kernel.h> |
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struct kvm_ptp_clock { |
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struct ptp_clock *ptp_clock; |
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struct ptp_clock_info caps; |
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}; |
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static DEFINE_SPINLOCK(kvm_ptp_lock); |
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static struct pvclock_vsyscall_time_info *hv_clock; |
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static struct kvm_clock_pairing clock_pair; |
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static phys_addr_t clock_pair_gpa; |
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static int ptp_kvm_get_time_fn(ktime_t *device_time, |
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struct system_counterval_t *system_counter, |
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void *ctx) |
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{ |
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unsigned long ret; |
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struct timespec64 tspec; |
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unsigned version; |
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int cpu; |
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struct pvclock_vcpu_time_info *src; |
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spin_lock(&kvm_ptp_lock); |
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preempt_disable_notrace(); |
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cpu = smp_processor_id(); |
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src = &hv_clock[cpu].pvti; |
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do { |
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/* |
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* We are using a TSC value read in the hosts |
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* kvm_hc_clock_pairing handling. |
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* So any changes to tsc_to_system_mul |
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* and tsc_shift or any other pvclock |
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* data invalidate that measurement. |
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*/ |
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version = pvclock_read_begin(src); |
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ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, |
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clock_pair_gpa, |
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KVM_CLOCK_PAIRING_WALLCLOCK); |
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if (ret != 0) { |
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pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret); |
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spin_unlock(&kvm_ptp_lock); |
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preempt_enable_notrace(); |
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return -EOPNOTSUPP; |
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} |
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tspec.tv_sec = clock_pair.sec; |
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tspec.tv_nsec = clock_pair.nsec; |
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ret = __pvclock_read_cycles(src, clock_pair.tsc); |
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} while (pvclock_read_retry(src, version)); |
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preempt_enable_notrace(); |
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system_counter->cycles = ret; |
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system_counter->cs = &kvm_clock; |
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*device_time = timespec64_to_ktime(tspec); |
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spin_unlock(&kvm_ptp_lock); |
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return 0; |
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} |
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static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp, |
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struct system_device_crosststamp *xtstamp) |
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{ |
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return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL, |
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NULL, xtstamp); |
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} |
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/* |
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* PTP clock operations |
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*/ |
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static int ptp_kvm_adjfreq(struct ptp_clock_info *ptp, s32 ppb) |
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{ |
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return -EOPNOTSUPP; |
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} |
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static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta) |
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{ |
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return -EOPNOTSUPP; |
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} |
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static int ptp_kvm_settime(struct ptp_clock_info *ptp, |
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const struct timespec64 *ts) |
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{ |
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return -EOPNOTSUPP; |
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} |
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static int ptp_kvm_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts) |
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{ |
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unsigned long ret; |
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struct timespec64 tspec; |
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spin_lock(&kvm_ptp_lock); |
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ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, |
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clock_pair_gpa, |
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KVM_CLOCK_PAIRING_WALLCLOCK); |
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if (ret != 0) { |
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pr_err_ratelimited("clock offset hypercall ret %lu\n", ret); |
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spin_unlock(&kvm_ptp_lock); |
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return -EOPNOTSUPP; |
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} |
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tspec.tv_sec = clock_pair.sec; |
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tspec.tv_nsec = clock_pair.nsec; |
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spin_unlock(&kvm_ptp_lock); |
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memcpy(ts, &tspec, sizeof(struct timespec64)); |
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return 0; |
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} |
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static int ptp_kvm_enable(struct ptp_clock_info *ptp, |
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struct ptp_clock_request *rq, int on) |
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{ |
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return -EOPNOTSUPP; |
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} |
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static const struct ptp_clock_info ptp_kvm_caps = { |
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.owner = THIS_MODULE, |
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.name = "KVM virtual PTP", |
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.max_adj = 0, |
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.n_ext_ts = 0, |
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.n_pins = 0, |
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.pps = 0, |
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.adjfreq = ptp_kvm_adjfreq, |
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.adjtime = ptp_kvm_adjtime, |
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.gettime64 = ptp_kvm_gettime, |
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.settime64 = ptp_kvm_settime, |
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.enable = ptp_kvm_enable, |
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.getcrosststamp = ptp_kvm_getcrosststamp, |
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}; |
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/* module operations */ |
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static struct kvm_ptp_clock kvm_ptp_clock; |
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static void __exit ptp_kvm_exit(void) |
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{ |
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ptp_clock_unregister(kvm_ptp_clock.ptp_clock); |
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} |
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static int __init ptp_kvm_init(void) |
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{ |
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long ret; |
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if (!kvm_para_available()) |
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return -ENODEV; |
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clock_pair_gpa = slow_virt_to_phys(&clock_pair); |
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hv_clock = pvclock_get_pvti_cpu0_va(); |
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if (!hv_clock) |
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return -ENODEV; |
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ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa, |
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KVM_CLOCK_PAIRING_WALLCLOCK); |
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if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP) |
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return -ENODEV; |
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kvm_ptp_clock.caps = ptp_kvm_caps; |
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kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL); |
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return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock); |
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} |
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module_init(ptp_kvm_init); |
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module_exit(ptp_kvm_exit); |
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MODULE_AUTHOR("Marcelo Tosatti <[email protected]>"); |
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MODULE_DESCRIPTION("PTP clock using KVMCLOCK"); |
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MODULE_LICENSE("GPL");
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