* the passage of time:
* (1) The host timestamp counter - read directly from HW and never written
* (2) A monotonic guest timestamp counter used to measure the progression of
- * time in the guest. This is computed using an offsets from (1) above.
+ * time in the guest. This is stored as an absolute number of cycles elapsed
+ * and is updated on guest entry and exit; it can also be updated explicitly
+ * in the monitor at times
* (3) The actual guest timestamp counter (which can be written by
* writing to the guest TSC MSR - MSR 0x10) from the monotonic guest TSC.
* This is also computed as an offset from (2) above when the TSC and
* this offset is updated when the TSC MSR is written.
*
- * The value used to offset the guest TSC from the host TSC is the *sum* of all
- * of these offsets (2 and 3) above
- *
* Because all other devices are slaved off of the passage of time in the guest,
* it is (2) above that drives the firing of other timers in the guest,
* including timer devices such as the Programmable Interrupt Timer (PIT).
/* We start running with guest_time == host_time */
uint64_t t = v3_get_host_time(&info->time_state);
- PrintDebug("Starting initial guest time as %llu\n", t);
-
info->time_state.enter_time = 0;
info->time_state.exit_time = t;
- info->time_state.last_update = t;
info->time_state.initial_time = t;
info->yield_start_cycle = t;
- return 0;
-}
-
-int v3_pause_time( struct guest_info * info )
-{
- struct vm_core_time * time_state = &(info->time_state);
- if (time_state->pause_time != 0) {
- PrintError("Attempted to pause time when time already paused.\n");
- return -1;
- }
- time_state->pause_time = v3_get_host_time( time_state );
-
- return 0;
-}
-
-int v3_resume_time( struct guest_info * info )
-{
- struct vm_core_time * time_state = &(info->time_state);
- uint64_t host_time, guest_time;
- sint64_t offset;
-
- if (time_state->pause_time == 0) {
- PrintError("Attempted to resume time when time not paused.\n");
- return -1;
- }
-
- host_time = v3_get_host_time(time_state);
- guest_time = v3_compute_guest_time(time_state, host_time);
- offset = (sint64_t)guest_time - (sint64_t)host_time;
- time_state->guest_host_offset = offset;
- time_state->pause_time = 0;
-
+ info->time_state.last_update = 0;
+ info->time_state.guest_cycles = 0;
+ PrintDebug("Starting time for core %d at host time %llu/guest time %llu.\n",
+ info->vcpu_id, t, info->time_state.guest_cycles);
+ v3_yield(info);
return 0;
}
{
struct vm_core_time * time_state = &(info->time_state);
PrintDebug("Adding additional offset of %lld to guest time.\n", offset);
- time_state->guest_host_offset += offset;
+ time_state->guest_cycles += offset;
return 0;
}
* time to account for the time paused even if the geust isn't
* usually paused in the VMM. */
host_time = v3_get_host_time(time_state);
- old_guest_time = v3_compute_guest_time(time_state, host_time);
+ old_guest_time = v3_get_guest_time(time_state);
target_host_time = compute_target_host_time(info, old_guest_time);
while (target_host_time > host_time) {
host_time = v3_get_host_time(time_state);
}
- guest_time = v3_compute_guest_time(time_state, host_time);
+ guest_time = v3_get_guest_time(time_state);
/* We do *not* assume the guest timer was paused in the VM. If it was
* this offseting is 0. If it wasn't, we need this. */
struct vm_core_time * time_state = &(info->time_state);
time_state->exit_time = v3_get_host_time(time_state);
-
-#ifdef V3_CONFIG_TIME_DILATION
- v3_pause_time( info );
-#endif
-
+ if (guest_cycles) {
+ time_state->guest_cycles += *guest_cycles;
+ } else {
+ uint64_t cycles_exec;
+ cycles_exec = time_state->exit_time - time_state->enter_time;
+ time_state->guest_cycles += cycles_exec;
+ }
return 0;
}
v3_time_enter_vm( struct guest_info * info )
{
struct vm_core_time * time_state = &(info->time_state);
- uint64_t host_time;
+ uint64_t host_time, vmm_cycles;
host_time = v3_get_host_time(time_state);
time_state->enter_time = host_time;
-#ifdef V3_CONFIG_TIME_DILATION
- v3_resume_time( info );
-#else
- time_state->guest_host_offset = 0;
-#endif
-
+ vmm_cycles = host_time - time_state->exit_time;
+ /* XXX How do we want to take into account host/guest CPU speed differences
+ * and time dilation here? Probably time just won't advance in the VMM in that
+ * case so its irrelvant XXX */
+ time_state->guest_cycles += vmm_cycles;
return 0;
}
ret = v3_register_hypercall(vm, TIME_CPUFREQ_HCALL,
handle_cpufreq_hcall, NULL);
- PrintDebug("Setting base time dilation factor.\n");
vm->time_state.td_mult = 1;
+ PrintDebug("Setting base time dilation factor to %d.\n", vm->time_state.td_mult);
return ret;
}
time_state->initial_time = 0;
time_state->last_update = 0;
- time_state->guest_host_offset = 0;
time_state->tsc_guest_offset = 0;
time_state->enter_time = 0;
time_state->exit_time = 0;
- time_state->pause_time = 0;
-
+ time_state->guest_cycles = 0;
INIT_LIST_HEAD(&(time_state->timers));
time_state->num_timers = 0;
