uint64_t t = v3_get_host_time(&info->time_state);
info->time_state.enter_time = 0;
- info->time_state.exit_time = t;
+ info->time_state.pause_time = t;
info->time_state.initial_time = t;
info->yield_start_cycle = t;
int v3_offset_time( struct guest_info * info, sint64_t offset )
{
struct vm_core_time * time_state = &(info->time_state);
- PrintDebug("Adding additional offset of %lld to guest time.\n", offset);
time_state->guest_cycles += offset;
return 0;
}
-#ifdef V3_CONFIG_TIME_DILATION
-static uint64_t compute_target_host_time(struct guest_info * info, uint64_t guest_time)
-{
- struct vm_core_time * time_state = &(info->time_state);
- uint64_t guest_elapsed, desired_elapsed;
-
- guest_elapsed = (guest_time - time_state->initial_time);
- desired_elapsed = (guest_elapsed * time_state->host_cpu_freq) / time_state->guest_cpu_freq;
- return time_state->initial_time + desired_elapsed;
-}
-
-static uint64_t compute_target_guest_time(struct guest_info *info)
-{
- struct vm_core_time * time_state = &(info->time_state);
- uint64_t host_elapsed, desired_elapsed;
-
- host_elapsed = v3_get_host_time(time_state) - time_state->initial_time;
- desired_elapsed = (host_elapsed * time_state->guest_cpu_freq) / time_state->host_cpu_freq;
-
- return time_state->initial_time + desired_elapsed;
-
-}
-
-/* Yield time in the host to deal with a guest that wants to run slower than
- * the native host cycle frequency */
-static int yield_host_time(struct guest_info * info) {
- struct vm_core_time * time_state = &(info->time_state);
- uint64_t host_time, target_host_time;
- uint64_t guest_time, old_guest_time;
-
- /* Now, let the host run while the guest is stopped to make the two
- * sync up. Note that this doesn't assume that guest time is stopped;
- * the offsetting in the next step will change add an offset to guest
- * 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_get_guest_time(time_state);
- target_host_time = compute_target_host_time(info, old_guest_time);
-
- while (target_host_time > host_time) {
- v3_yield(info);
- host_time = v3_get_host_time(time_state);
+int v3_skip_time(struct guest_info * info) {
+ if (info->vm_info->time_state.follow_host_time) {
+ PrintError("Cannot skip host time passage while slaved to host clock.\n");
+ return 1;
+ } else {
+ info->time_state.pause_time = v3_get_host_time(&info->time_state);
}
-
- 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. */
- v3_offset_time(info, (sint64_t)(old_guest_time - guest_time));
-
return 0;
}
-static int skew_guest_time(struct guest_info * info) {
- struct vm_core_time * time_state = &(info->time_state);
- uint64_t target_guest_time, guest_time;
- /* Now the host may have gotten ahead of the guest because
- * yielding is a coarse grained thing. Figure out what guest time
- * we want to be at, and use the use the offsetting mechanism in
- * the VMM to make the guest run forward. We limit *how* much we skew
- * it forward to prevent the guest time making large jumps,
- * however. */
- target_guest_time = compute_target_guest_time(info);
- guest_time = v3_get_guest_time(time_state);
-
- if (guest_time < target_guest_time) {
- sint64_t max_skew, desired_skew, skew;
-
- if (time_state->enter_time) {
- /* Limit forward skew to 10% of the amount the guest has
- * run since we last could skew time */
- max_skew = (sint64_t)(guest_time - time_state->enter_time) / 10;
- } else {
- max_skew = 0;
- }
-
- desired_skew = (sint64_t)(target_guest_time - guest_time);
- skew = desired_skew > max_skew ? max_skew : desired_skew;
- PrintDebug("Guest %lld cycles behind where it should be.\n",
- desired_skew);
- PrintDebug("Limit on forward skew is %lld. Skewing forward %lld.\n",
- max_skew, skew);
-
- v3_offset_time(info, skew);
+int v3_advance_time(struct guest_info * info) {
+ uint64_t t = v3_get_host_time(&info->time_state);
+ if (info->vm_info->time_state.follow_host_time) {
+ /* How many guest cycles should have elapsed? */
+ sint64_t host_elapsed = t - info->time_state.initial_time;
+ sint64_t guest_target = (host_elapsed * info->time_state.guest_cpu_freq) / info->time_state.host_cpu_freq;
+ sint64_t cycle_lag = guest_target - info->time_state.guest_cycles;
+ v3_offset_time(info, cycle_lag);
+ } else {
+ v3_offset_time(info, (sint64_t)(t - info->time_state.pause_time));
}
+ info->time_state.pause_time = t;
return 0;
}
-#endif /* V3_CONFIG_TIME_DILATION */
-
-// Control guest time in relation to host time so that the two stay
-// appropriately synchronized to the extent possible.
-int v3_adjust_time(struct guest_info * info) {
-
-#ifdef V3_CONFIG_TIME_DILATION
- /* First deal with yielding if we want to slow down the guest */
- yield_host_time(info);
-
- /* Now, if the guest is too slow, (either from excess yielding above,
- * or because the VMM is doing something that takes a long time to emulate)
- * allow guest time to jump forward a bit */
- skew_guest_time(info);
-#endif
- return 0;
-}
/* Called immediately upon entry in the the VMM */
int
{
struct vm_core_time * time_state = &(info->time_state);
- time_state->exit_time = v3_get_host_time(time_state);
+ time_state->pause_time = v3_get_host_time(time_state);
if (guest_cycles) {
time_state->guest_cycles += *guest_cycles;
} else {
- uint64_t cycles_exec;
- cycles_exec = time_state->exit_time - time_state->enter_time;
+ sint64_t cycles_exec;
+ cycles_exec = (sint64_t)(time_state->pause_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, vmm_cycles;
+ uint64_t host_time = v3_get_host_time(&info->time_state);
- host_time = v3_get_host_time(time_state);
+ v3_advance_time(info);
time_state->enter_time = host_time;
- 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;
}
new_tsc = (((uint64_t)msr_val.hi) << 32) | (uint64_t)msr_val.lo;
guest_time = v3_get_guest_time(time_state);
- time_state->tsc_guest_offset = (sint64_t)new_tsc - (sint64_t)guest_time;
+ time_state->tsc_guest_offset = (sint64_t)(new_tsc - guest_time);
return 0;
}
vm->time_state.td_mult = 1;
PrintDebug("Setting base time dilation factor to %d.\n", vm->time_state.td_mult);
+ vm->time_state.follow_host_time = 1;
+ PrintDebug("Locking guest time to host time.\n");
return ret;
}
time_state->last_update = 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));
