hw/i386/kvm/clock.c

   1 /*
   2  * QEMU KVM support, paravirtual clock device
   3  *
   4  * Copyright (C) 2011 Siemens AG
   5  *
   6  * Authors:
   7  *  Jan Kiszka        <jan.kiszka@siemens.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL version 2.
  10  * See the COPYING file in the top-level directory.
  11  *
  12  * Contributions after 2012-01-13 are licensed under the terms of the
  13  * GNU GPL, version 2 or (at your option) any later version.
  14  */
  15
  16 #include "qemu/osdep.h"
  17 #include "qemu-common.h"
  18 #include "cpu.h"
  19 #include "qemu/host-utils.h"
  20 #include "sysemu/sysemu.h"
  21 #include "sysemu/kvm.h"
  22 #include "kvm_i386.h"
  23 #include "hw/sysbus.h"
  24 #include "hw/kvm/clock.h"
  25
  26 #include <linux/kvm.h>
  27 #include <linux/kvm_para.h>
  28
  29 #define TYPE_KVM_CLOCK "kvmclock"
  30 #define KVM_CLOCK(obj) OBJECT_CHECK(KVMClockState, (obj), TYPE_KVM_CLOCK)
  31
  32 typedef struct KVMClockState {
  33     /*< private >*/
  34     SysBusDevice busdev;
  35     /*< public >*/
  36
  37     uint64_t clock;
  38     bool clock_valid;
  39 } KVMClockState;
  40
  41 struct pvclock_vcpu_time_info {
  42     uint32_t   version;
  43     uint32_t   pad0;
  44     uint64_t   tsc_timestamp;
  45     uint64_t   system_time;
  46     uint32_t   tsc_to_system_mul;
  47     int8_t     tsc_shift;
  48     uint8_t    flags;
  49     uint8_t    pad[2];
  50 } __attribute__((__packed__)); /* 32 bytes */
  51
  52 static uint64_t kvmclock_current_nsec(KVMClockState *s)
  53 {
  54     CPUState *cpu = first_cpu;
  55     CPUX86State *env = cpu->env_ptr;
  56     hwaddr kvmclock_struct_pa = env->system_time_msr & ~1ULL;
  57     uint64_t migration_tsc = env->tsc;
  58     struct pvclock_vcpu_time_info time;
  59     uint64_t delta;
  60     uint64_t nsec_lo;
  61     uint64_t nsec_hi;
  62     uint64_t nsec;
  63
  64     if (!(env->system_time_msr & 1ULL)) {
  65         /* KVM clock not active */
  66         return 0;
  67     }
  68
  69     cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time));
  70
  71     assert(time.tsc_timestamp <= migration_tsc);
  72     delta = migration_tsc - time.tsc_timestamp;
  73     if (time.tsc_shift < 0) {
  74         delta >>= -time.tsc_shift;
  75     } else {
  76         delta <<= time.tsc_shift;
  77     }
  78
  79     mulu64(&nsec_lo, &nsec_hi, delta, time.tsc_to_system_mul);
  80     nsec = (nsec_lo >> 32) | (nsec_hi << 32);
  81     return nsec + time.system_time;
  82 }
  83
  84 static void kvmclock_vm_state_change(void *opaque, int running,
  85                                      RunState state)
  86 {
  87     KVMClockState *s = opaque;
  88     CPUState *cpu;
  89     int cap_clock_ctrl = kvm_check_extension(kvm_state, KVM_CAP_KVMCLOCK_CTRL);
  90     int ret;
  91
  92     if (running) {
  93         struct kvm_clock_data data = {};
  94         uint64_t time_at_migration = kvmclock_current_nsec(s);
  95
  96         s->clock_valid = false;
  97
  98         /* We can't rely on the migrated clock value, just discard it */
  99         if (time_at_migration) {
 100             s->clock = time_at_migration;
 101         }
 102
 103         data.clock = s->clock;
 104         ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
 105         if (ret < 0) {
 106             fprintf(stderr, "KVM_SET_CLOCK failed: %s\n", strerror(ret));
 107             abort();
 108         }
 109
 110         if (!cap_clock_ctrl) {
 111             return;
 112         }
 113         CPU_FOREACH(cpu) {
 114             ret = kvm_vcpu_ioctl(cpu, KVM_KVMCLOCK_CTRL, 0);
 115             if (ret) {
 116                 if (ret != -EINVAL) {
 117                     fprintf(stderr, "%s: %s\n", __func__, strerror(-ret));
 118                 }
 119                 return;
 120             }
 121         }
 122     } else {
 123         struct kvm_clock_data data;
 124         int ret;
 125
 126         if (s->clock_valid) {
 127             return;
 128         }
 129
 130         kvm_synchronize_all_tsc();
 131
 132         ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
 133         if (ret < 0) {
 134             fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
 135             abort();
 136         }
 137         s->clock = data.clock;
 138
 139         /*
 140          * If the VM is stopped, declare the clock state valid to
 141          * avoid re-reading it on next vmsave (which would return
 142          * a different value). Will be reset when the VM is continued.
 143          */
 144         s->clock_valid = true;
 145     }
 146 }
 147
 148 static void kvmclock_realize(DeviceState *dev, Error **errp)
 149 {
 150     KVMClockState *s = KVM_CLOCK(dev);
 151
 152     qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s);
 153 }
 154
 155 static const VMStateDescription kvmclock_vmsd = {
 156     .name = "kvmclock",
 157     .version_id = 1,
 158     .minimum_version_id = 1,
 159     .fields = (VMStateField[]) {
 160         VMSTATE_UINT64(clock, KVMClockState),
 161         VMSTATE_END_OF_LIST()
 162     }
 163 };
 164
 165 static void kvmclock_class_init(ObjectClass *klass, void *data)
 166 {
 167     DeviceClass *dc = DEVICE_CLASS(klass);
 168
 169     dc->realize = kvmclock_realize;
 170     dc->vmsd = &kvmclock_vmsd;
 171 }
 172
 173 static const TypeInfo kvmclock_info = {
 174     .name          = TYPE_KVM_CLOCK,
 175     .parent        = TYPE_SYS_BUS_DEVICE,
 176     .instance_size = sizeof(KVMClockState),
 177     .class_init    = kvmclock_class_init,
 178 };
 179
 180 /* Note: Must be called after VCPU initialization. */
 181 void kvmclock_create(void)
 182 {
 183     X86CPU *cpu = X86_CPU(first_cpu);
 184
 185     if (kvm_enabled() &&
 186         cpu->env.features[FEAT_KVM] & ((1ULL << KVM_FEATURE_CLOCKSOURCE) |
 187                                        (1ULL << KVM_FEATURE_CLOCKSOURCE2))) {
 188         sysbus_create_simple(TYPE_KVM_CLOCK, -1, NULL);
 189     }
 190 }
 191
 192 static void kvmclock_register_types(void)
 193 {
 194     type_register_static(&kvmclock_info);
 195 }
 196
 197 type_init(kvmclock_register_types)