1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Virtual PTP 1588 clock for use with KVM guests 4 * 5 * Copyright (C) 2017 Red Hat Inc. 6 */ 7 8 #include <linux/device.h> 9 #include <linux/kernel.h> 10 #include <asm/pvclock.h> 11 #include <asm/kvmclock.h> 12 #include <linux/module.h> 13 #include <uapi/asm/kvm_para.h> 14 #include <uapi/linux/kvm_para.h> 15 #include <linux/ptp_clock_kernel.h> 16 #include <linux/ptp_kvm.h> 17 18 static phys_addr_t clock_pair_gpa; 19 static struct kvm_clock_pairing clock_pair; 20 21 int kvm_arch_ptp_init(void) 22 { 23 long ret; 24 25 if (!kvm_para_available()) 26 return -ENODEV; 27 28 clock_pair_gpa = slow_virt_to_phys(&clock_pair); 29 if (!pvclock_get_pvti_cpu0_va()) 30 return -ENODEV; 31 32 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa, 33 KVM_CLOCK_PAIRING_WALLCLOCK); 34 if (ret == -KVM_ENOSYS || ret == -KVM_EOPNOTSUPP) 35 return -ENODEV; 36 37 return 0; 38 } 39 40 int kvm_arch_ptp_get_clock(struct timespec64 *ts) 41 { 42 long ret; 43 44 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, 45 clock_pair_gpa, 46 KVM_CLOCK_PAIRING_WALLCLOCK); 47 if (ret != 0) { 48 pr_err_ratelimited("clock offset hypercall ret %lu\n", ret); 49 return -EOPNOTSUPP; 50 } 51 52 ts->tv_sec = clock_pair.sec; 53 ts->tv_nsec = clock_pair.nsec; 54 55 return 0; 56 } 57 58 int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *tspec, 59 struct clocksource **cs) 60 { 61 struct pvclock_vcpu_time_info *src; 62 unsigned int version; 63 long ret; 64 65 src = this_cpu_pvti(); 66 67 do { 68 /* 69 * We are using a TSC value read in the hosts 70 * kvm_hc_clock_pairing handling. 71 * So any changes to tsc_to_system_mul 72 * and tsc_shift or any other pvclock 73 * data invalidate that measurement. 74 */ 75 version = pvclock_read_begin(src); 76 77 ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, 78 clock_pair_gpa, 79 KVM_CLOCK_PAIRING_WALLCLOCK); 80 if (ret != 0) { 81 pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret); 82 return -EOPNOTSUPP; 83 } 84 tspec->tv_sec = clock_pair.sec; 85 tspec->tv_nsec = clock_pair.nsec; 86 *cycle = __pvclock_read_cycles(src, clock_pair.tsc); 87 } while (pvclock_read_retry(src, version)); 88 89 *cs = &kvm_clock; 90 91 return 0; 92 } 93