ptp_kvm_x86.c 2.0 KB

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  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. #include <linux/device.h>
  8. #include <linux/kernel.h>
  9. #include <asm/pvclock.h>
  10. #include <asm/kvmclock.h>
  11. #include <linux/module.h>
  12. #include <uapi/asm/kvm_para.h>
  13. #include <uapi/linux/kvm_para.h>
  14. #include <linux/ptp_clock_kernel.h>
  15. #include <linux/ptp_kvm.h>
  16. static phys_addr_t clock_pair_gpa;
  17. static struct kvm_clock_pairing clock_pair;
  18. int kvm_arch_ptp_init(void)
  19. {
  20. long ret;
  21. if (!kvm_para_available())
  22. return -ENODEV;
  23. clock_pair_gpa = slow_virt_to_phys(&clock_pair);
  24. if (!pvclock_get_pvti_cpu0_va())
  25. return -ENODEV;
  26. ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING, clock_pair_gpa,
  27. KVM_CLOCK_PAIRING_WALLCLOCK);
  28. if (ret == -KVM_ENOSYS)
  29. return -ENODEV;
  30. return ret;
  31. }
  32. int kvm_arch_ptp_get_clock(struct timespec64 *ts)
  33. {
  34. long ret;
  35. ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
  36. clock_pair_gpa,
  37. KVM_CLOCK_PAIRING_WALLCLOCK);
  38. if (ret != 0) {
  39. pr_err_ratelimited("clock offset hypercall ret %lu\n", ret);
  40. return -EOPNOTSUPP;
  41. }
  42. ts->tv_sec = clock_pair.sec;
  43. ts->tv_nsec = clock_pair.nsec;
  44. return 0;
  45. }
  46. int kvm_arch_ptp_get_crosststamp(u64 *cycle, struct timespec64 *tspec,
  47. struct clocksource **cs)
  48. {
  49. struct pvclock_vcpu_time_info *src;
  50. unsigned int version;
  51. long ret;
  52. src = this_cpu_pvti();
  53. do {
  54. /*
  55. * We are using a TSC value read in the hosts
  56. * kvm_hc_clock_pairing handling.
  57. * So any changes to tsc_to_system_mul
  58. * and tsc_shift or any other pvclock
  59. * data invalidate that measurement.
  60. */
  61. version = pvclock_read_begin(src);
  62. ret = kvm_hypercall2(KVM_HC_CLOCK_PAIRING,
  63. clock_pair_gpa,
  64. KVM_CLOCK_PAIRING_WALLCLOCK);
  65. if (ret != 0) {
  66. pr_err_ratelimited("clock pairing hypercall ret %lu\n", ret);
  67. return -EOPNOTSUPP;
  68. }
  69. tspec->tv_sec = clock_pair.sec;
  70. tspec->tv_nsec = clock_pair.nsec;
  71. *cycle = __pvclock_read_cycles(src, clock_pair.tsc);
  72. } while (pvclock_read_retry(src, version));
  73. *cs = &kvm_clock;
  74. return 0;
  75. }