diff options
Diffstat (limited to 'drivers/ptp/ptp_kvm.c')
| -rw-r--r-- | drivers/ptp/ptp_kvm.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/drivers/ptp/ptp_kvm.c b/drivers/ptp/ptp_kvm.c new file mode 100644 index 000000000..658d33fc3 --- /dev/null +++ b/drivers/ptp/ptp_kvm.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Virtual PTP 1588 clock for use with KVM guests + * + * Copyright (C) 2017 Red Hat Inc. + */ +#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; +}; + +static 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; +} + +static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp, + struct system_device_crosststamp *xtstamp) +{ + return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL, + NULL, xtstamp); +} + +/* + * PTP clock operations + */ + +static int ptp_kvm_adjfreq(struct ptp_clock_info *ptp, s32 ppb) +{ + return -EOPNOTSUPP; +} + +static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta) +{ + return -EOPNOTSUPP; +} + +static int ptp_kvm_settime(struct ptp_clock_info *ptp, + const struct timespec64 *ts) +{ + return -EOPNOTSUPP; +} + +static int ptp_kvm_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts) +{ + unsigned long ret; + struct timespec64 tspec; + + spin_lock(&kvm_ptp_lock); + + ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, + clock_pair_gpa, + KVM_CLOCK_PAIRING_WALLCLOCK); + if (ret != 0) { + pr_err_ratelimited("clock offset hypercall ret %lu\n", ret); + spin_unlock(&kvm_ptp_lock); + return -EOPNOTSUPP; + } + + tspec.tv_sec = clock_pair.sec; + tspec.tv_nsec = clock_pair.nsec; + spin_unlock(&kvm_ptp_lock); + + memcpy(ts, &tspec, sizeof(struct timespec64)); + + return 0; +} + +static int ptp_kvm_enable(struct ptp_clock_info *ptp, + struct ptp_clock_request *rq, int on) +{ + return -EOPNOTSUPP; +} + +static const struct ptp_clock_info ptp_kvm_caps = { + .owner = THIS_MODULE, + .name = "KVM virtual PTP", + .max_adj = 0, + .n_ext_ts = 0, + .n_pins = 0, + .pps = 0, + .adjfreq = ptp_kvm_adjfreq, + .adjtime = ptp_kvm_adjtime, + .gettime64 = ptp_kvm_gettime, + .settime64 = ptp_kvm_settime, + .enable = ptp_kvm_enable, + .getcrosststamp = ptp_kvm_getcrosststamp, +}; + +/* module operations */ + +static struct kvm_ptp_clock kvm_ptp_clock; + +static void __exit ptp_kvm_exit(void) +{ + ptp_clock_unregister(kvm_ptp_clock.ptp_clock); +} + +static int __init ptp_kvm_init(void) +{ + long ret; + + if (!kvm_para_available()) + return -ENODEV; + + clock_pair_gpa = slow_virt_to_phys(&clock_pair); + hv_clock = pvclock_get_pvti_cpu0_va(); + + if (!hv_clock) + return -ENODEV; + + ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa, + KVM_CLOCK_PAIRING_WALLCLOCK); + if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP) + return -ENODEV; + + kvm_ptp_clock.caps = ptp_kvm_caps; + + kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL); + + return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock); +} + +module_init(ptp_kvm_init); +module_exit(ptp_kvm_exit); + +MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>"); +MODULE_DESCRIPTION("PTP clock using KVMCLOCK"); +MODULE_LICENSE("GPL"); |