* 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 as a multipler/offset from (1) above
+ * time in the guest. This is computed using an offsets from (1) above.
* (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).
*
- *
- *
+ * Future additions:
+ * (1) Add support for temporarily skewing guest time off of where it should
+ * be to support slack simulation of guests. The idea is that simulators
+ * set this skew to be the difference between how much time passed for a
+ * simulated feature and a real implementation of that feature, making
+ * pass at a different rate from real time on this core. The VMM will then
+ * attempt to move this skew back towards 0 subject to resolution/accuracy
+ * constraints from various system timers.
+ *
+ * The main effort in doing this will be to get accuracy/resolution
+ * information from each local timer and to use this to bound how much skew
+ * is removed on each exit.
*/
} else {
uint64_t guest_time, guest_elapsed, desired_elapsed;
uint64_t host_time, target_host_time;
+
guest_time = v3_get_guest_time(time_state);
+
+ /* Compute what host time this guest time should correspond to. */
guest_elapsed = (guest_time - time_state->initial_time);
desired_elapsed = (guest_elapsed * time_state->host_cpu_freq) / time_state->guest_cpu_freq;
-
target_host_time = time_state->initial_time + desired_elapsed;
- host_time = v3_get_host_time(time_state);
- PrintDebug("Core %d: Yielding %Lu cycles for guest frequency mismatch "
- "(%Lu cycles elapsed in guest, %Lu in host).\n",
- info->cpu_id, target_host_time - host_time,
- guest_elapsed, host_time - time_state->initial_time);
+ /* Yield until that host time is reached */
host_time = v3_get_host_time(time_state);
+
while (host_time < target_host_time) {
v3_yield(info);
host_time = v3_get_host_time(time_state);
}
- PrintDebug("Core %d: done adjusting time at host time %Lu.\n",
- info->cpu_id, host_time);
- time_state->guest_host_offset = guest_time - host_time;
-
+ time_state->guest_host_offset = (sint64_t)guest_time - (sint64_t)host_time;
}
+
return 0;
}
-int v3_add_timer(struct guest_info * info, struct vm_timer_ops * ops,
- void * private_data) {
- struct vm_timer * timer = NULL;
- timer = (struct vm_timer *)V3_Malloc(sizeof(struct vm_timer));
+struct v3_timer * v3_add_timer(struct guest_info * info,
+ struct v3_timer_ops * ops,
+ void * private_data) {
+ struct v3_timer * timer = NULL;
+ timer = (struct v3_timer *)V3_Malloc(sizeof(struct v3_timer));
V3_ASSERT(timer != NULL);
timer->ops = ops;
list_add(&(timer->timer_link), &(info->time_state.timers));
info->time_state.num_timers++;
- return 0;
+ return timer;
}
-int v3_remove_timer(struct guest_info * info, struct vm_timer * timer) {
+int v3_remove_timer(struct guest_info * info, struct v3_timer * timer) {
list_del(&(timer->timer_link));
info->time_state.num_timers--;
}
void v3_update_timers(struct guest_info * info) {
- struct vm_timer * tmp_timer;
+ struct v3_timer * tmp_timer;
uint64_t old_time = info->time_state.last_update;
uint64_t cycles;
/*
* Handle full virtualization of the time stamp counter. As noted
* above, we don't store the actual value of the TSC, only the guest's
- * offset from the host TSC. If the guest write's the to TSC, we handle
- * this by changing that offset.
+ * offset from monotonic guest's time. If the guest writes to the TSC, we
+ * handle this by changing that offset.
+ *
+ * Possible TODO: Proper hooking of TSC read/writes?
*/
int v3_rdtsc(struct guest_info * info) {
* ra/c/dx here since they're modified by this instruction anyway. */
info->vm_regs.rcx = TSC_AUX_MSR;
ret = v3_handle_msr_read(info);
- if (ret) return ret;
+
+ if (ret != 0) {
+ return ret;
+ }
+
info->vm_regs.rcx = info->vm_regs.rax;
- /* Now do the TSC half of the instruction, which may hit the normal
- * TSC hook if it exists */
+ /* Now do the TSC half of the instruction */
ret = v3_rdtsc(info);
- if (ret) return ret;
-
+
+ if (ret != 0) {
+ return ret;
+ }
+
return 0;
}
return 0;
}
-#if 0
static int tsc_aux_msr_read_hook(struct guest_info *info, uint_t msr_num,
struct v3_msr *msr_val, void *priv) {
struct vm_time * time_state = &(info->time_state);
V3_ASSERT(msr_num == TSC_AUX_MSR);
+
msr_val->lo = time_state->tsc_aux.lo;
msr_val->hi = time_state->tsc_aux.hi;
struct vm_time * time_state = &(info->time_state);
V3_ASSERT(msr_num == TSC_AUX_MSR);
+
time_state->tsc_aux.lo = msr_val.lo;
time_state->tsc_aux.hi = msr_val.hi;
uint64_t time = v3_get_guest_tsc(&info->time_state);
V3_ASSERT(msr_num == TSC_MSR);
+
msr_val->hi = time >> 32;
msr_val->lo = time & 0xffffffffLL;
struct v3_msr msr_val, void *priv) {
struct vm_time * time_state = &(info->time_state);
uint64_t guest_time, new_tsc;
+
V3_ASSERT(msr_num == TSC_MSR);
+
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;
return 0;
}
-#endif
-static int init_vm_time(struct v3_vm_info *vm_info) {
+int v3_init_time_vm(struct v3_vm_info * vm) {
int ret;
-#if 0
PrintDebug("Installing TSC MSR hook.\n");
- ret = v3_hook_msr(vm_info, TSC_MSR,
+ ret = v3_hook_msr(vm, TSC_MSR,
tsc_msr_read_hook, tsc_msr_write_hook, NULL);
+ if (ret != 0) {
+ return ret;
+ }
+
PrintDebug("Installing TSC_AUX MSR hook.\n");
- if (ret) return ret;
- ret = v3_hook_msr(vm_info, TSC_AUX_MSR, tsc_aux_msr_read_hook,
+ ret = v3_hook_msr(vm, TSC_AUX_MSR, tsc_aux_msr_read_hook,
tsc_aux_msr_write_hook, NULL);
- if (ret) return ret;
-#endif
+
+ if (ret != 0) {
+ return ret;
+ }
PrintDebug("Registering TIME_CPUFREQ hypercall.\n");
- ret = v3_register_hypercall(vm_info, TIME_CPUFREQ_HCALL,
+ ret = v3_register_hypercall(vm, TIME_CPUFREQ_HCALL,
handle_cpufreq_hcall, NULL);
+
return ret;
}
-void v3_init_time(struct guest_info * info) {
+void v3_deinit_time_vm(struct v3_vm_info * vm) {
+ v3_unhook_msr(vm, TSC_MSR);
+ v3_unhook_msr(vm, TSC_AUX_MSR);
+
+ v3_remove_hypercall(vm, TIME_CPUFREQ_HCALL);
+}
+
+void v3_init_time_core(struct guest_info * info) {
struct vm_time * time_state = &(info->time_state);
v3_cfg_tree_t * cfg_tree = info->core_cfg_data;
- static int one_time = 0;
- char *khz;
+ char * khz = NULL;
time_state->host_cpu_freq = V3_CPU_KHZ();
khz = v3_cfg_val(cfg_tree, "khz");
+
if (khz) {
time_state->guest_cpu_freq = atoi(khz);
PrintDebug("Core %d CPU frequency requested at %d khz.\n",
info->cpu_id, time_state->guest_cpu_freq);
}
- if (!khz || time_state->guest_cpu_freq > time_state->host_cpu_freq) {
+ if ((khz == NULL) || (time_state->guest_cpu_freq > time_state->host_cpu_freq)) {
time_state->guest_cpu_freq = time_state->host_cpu_freq;
}
- PrintDebug("Core %d CPU frequency set to %d KHz (host CPU frequency = %d KHz).\n", info->cpu_id, time_state->guest_cpu_freq, time_state->host_cpu_freq);
+
+ PrintDebug("Core %d CPU frequency set to %d KHz (host CPU frequency = %d KHz).\n",
+ info->cpu_id,
+ time_state->guest_cpu_freq,
+ time_state->host_cpu_freq);
time_state->initial_time = 0;
time_state->last_update = 0;
time_state->tsc_aux.lo = 0;
time_state->tsc_aux.hi = 0;
- if (!one_time) {
- init_vm_time(info->vm_info);
- one_time = 1;
+
+}
+
+
+void v3_deinit_time_core(struct guest_info * core) {
+ struct vm_time * time_state = &(core->time_state);
+ struct v3_timer * tmr = NULL;
+ struct v3_timer * tmp = NULL;
+
+ list_for_each_entry_safe(tmr, tmp, &(time_state->timers), timer_link) {
+ v3_remove_timer(core, tmr);
}
+
}