X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=blobdiff_plain;f=palacios%2Fsrc%2Fpalacios%2Fvmm_time.c;h=fa8f5cde8755b15191f1f4683ccab4c82e4b9c01;hb=f88a692d094459f0326c5c891df5ea81b5476ba6;hp=357bae426fd635a4c40c72b9c8afd0bb22236546;hpb=f18097c35ddc13572ab41e03ad7a14430cff11ac;p=palacios.git diff --git a/palacios/src/palacios/vmm_time.c b/palacios/src/palacios/vmm_time.c index 357bae4..fa8f5cd 100644 --- a/palacios/src/palacios/vmm_time.c +++ b/palacios/src/palacios/vmm_time.c @@ -22,7 +22,7 @@ #include #include -#ifndef CONFIG_DEBUG_TIME +#ifndef V3_CONFIG_DEBUG_TIME #undef PrintDebug #define PrintDebug(fmt, args...) #endif @@ -104,23 +104,44 @@ int v3_offset_time( struct guest_info * info, sint64_t offset ) return 0; } -// 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) { +static uint64_t compute_target_host_time(struct guest_info * info) +{ + struct vm_time * time_state = &(info->time_state); + uint64_t guest_elapsed, desired_elapsed; + + guest_elapsed = (v3_get_guest_time(time_state) - 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_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_time * time_state = &(info->time_state); uint64_t host_time, target_host_time; - uint64_t guest_time, target_guest_time, old_guest_time; - uint64_t guest_elapsed, host_elapsed, desired_elapsed; + uint64_t guest_time, old_guest_time; /* Compute the target host time given how much time has *already* * passed in the guest */ - guest_time = v3_get_guest_time(time_state); - 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; - + target_host_time = compute_target_host_time(info); + /* Now, let the host run while the guest is stopped to make the two - * sync up. */ + * 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); @@ -131,38 +152,60 @@ int v3_adjust_time(struct guest_info * info) { 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. + /* 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 - (sint64_t)guest_time); + return 0; +} + +static int skew_guest_time(struct guest_info * info) { + struct vm_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. */ - host_elapsed = host_time - time_state->initial_time; - desired_elapsed = (host_elapsed * time_state->guest_cpu_freq) / time_state->host_cpu_freq; - target_guest_time = time_state->initial_time + desired_elapsed; + target_guest_time = compute_target_guest_time(info); + guest_time = v3_get_guest_time(time_state); if (guest_time < target_guest_time) { - uint64_t max_skew, desired_skew, skew; + sint64_t max_skew, desired_skew, skew; if (time_state->enter_time) { - max_skew = (time_state->exit_time - time_state->enter_time) / 10; + /* Limit forward skew to 10% of the amount the guest has + * run since we last could skew time */ + max_skew = ((sint64_t)guest_time - (sint64_t)time_state->enter_time) / 10; } else { max_skew = 0; } - desired_skew = target_guest_time - guest_time; + desired_skew = (sint64_t)target_guest_time - (sint64_t)guest_time; skew = desired_skew > max_skew ? max_skew : desired_skew; -/* PrintDebug("Guest %llu cycles behind where it should be.\n", + PrintDebug("Guest %lld cycles behind where it should be.\n", desired_skew); - PrintDebug("Limit on forward skew is %llu. Skewing forward %llu.\n", - max_skew, skew); */ + PrintDebug("Limit on forward skew is %lld. Skewing forward %lld.\n", + max_skew, skew); v3_offset_time(info, skew); } + + return 0; +} + +// 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) { + + /* 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); return 0; } @@ -185,15 +228,10 @@ v3_time_enter_vm( struct guest_info * info ) struct vm_time * time_state = &(info->time_state); uint64_t guest_time, host_time; - guest_time = v3_get_guest_time(time_state); host_time = v3_get_host_time(time_state); + guest_time = v3_get_guest_time(time_state); time_state->enter_time = host_time; - time_state->guest_host_offset = guest_time - host_time; - - // Because we just modified the offset - shouldn't matter as this should be - // the last time-related call prior to entering the VMM, but worth it - // just in case. - time_state->exit_time = host_time; + time_state->guest_host_offset = (sint64_t)guest_time - (sint64_t)host_time; return 0; } @@ -232,7 +270,9 @@ void v3_update_timers(struct guest_info * info) { time_state->last_update = v3_get_guest_time(time_state); cycles = time_state->last_update - old_time; + V3_ASSERT(cycles >= 0); + // V3_Print("Updating timers with %lld elapsed cycles.\n", cycles); list_for_each_entry(tmp_timer, &(time_state->timers), timer_link) { tmp_timer->ops->update_timer(info, cycles, time_state->guest_cpu_freq, tmp_timer->private_data); } @@ -399,8 +439,8 @@ void v3_init_time_core(struct guest_info * info) { 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); + PrintDebug("Logical Core %d (vcpu=%d) CPU frequency requested at %d khz.\n", + info->pcpu_id, info->vcpu_id, time_state->guest_cpu_freq); } if ( (khz == NULL) || @@ -410,8 +450,8 @@ void v3_init_time_core(struct guest_info * info) { 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, + PrintDebug("Logical Core %d (vcpu=%d) CPU frequency set to %d KHz (host CPU frequency = %d KHz).\n", + info->pcpu_id, info->vcpu_id, time_state->guest_cpu_freq, time_state->host_cpu_freq);