X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=blobdiff_plain;f=palacios%2Fsrc%2Fpalacios%2Fvmm_time.c;h=357bae426fd635a4c40c72b9c8afd0bb22236546;hb=95290c36e27daf208b8e61e6c6f26325db8b6b4d;hp=6b5fc1396458c2aa36d9147476141aea2b2c26eb;hpb=d54fc24e6cfb62cc2fedfb63d3ae68ff636e3a01;p=palacios.git diff --git a/palacios/src/palacios/vmm_time.c b/palacios/src/palacios/vmm_time.c index 6b5fc13..357bae4 100644 --- a/palacios/src/palacios/vmm_time.c +++ b/palacios/src/palacios/vmm_time.c @@ -18,8 +18,8 @@ * redistribute, and modify it as specified in the file "V3VEE_LICENSE". */ -#include #include +#include #include #ifndef CONFIG_DEBUG_TIME @@ -86,92 +86,119 @@ int v3_start_time(struct guest_info * info) { uint64_t t = v3_get_host_time(&info->time_state); PrintDebug("Starting initial guest time as %llu\n", t); -#ifdef CONFIG_TIME_HIDE_VM_COST - info->time_state.pause_time = t; -#else - info->time_state.pause_time = 0; -#endif + + 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; } -// If the guest is supposed to run slower than the host, yield out until -// the host time is appropriately far along; -int v3_adjust_time(struct guest_info * info) { +int v3_offset_time( struct guest_info * info, sint64_t offset ) +{ struct vm_time * time_state = &(info->time_state); +// PrintDebug("Adding additional offset of %lld to guest time.\n", offset); + time_state->guest_host_offset += offset; + return 0; +} - if (time_state->host_cpu_freq != time_state->guest_cpu_freq) { - uint64_t guest_time, host_time, target_host_time; - sint64_t guest_elapsed, desired_elapsed; +// 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) { + 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; - guest_time = v3_get_guest_time(time_state); + /* 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; - /* 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; + /* Now, let the host run while the guest is stopped to make the two + * sync up. */ + host_time = v3_get_host_time(time_state); + old_guest_time = v3_get_guest_time(time_state); - /* Yield until that host time is reached */ + while (target_host_time > host_time) { + v3_yield(info); host_time = v3_get_host_time(time_state); + } - if (host_time < target_host_time) { - PrintDebug("Yielding until host time (%llu) greater than target (%llu).\n", host_time, target_host_time); - } + guest_time = v3_get_guest_time(time_state); - while (host_time < target_host_time) { - v3_yield(info); - host_time = v3_get_host_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 - (sint64_t)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; + + if (guest_time < target_guest_time) { + uint64_t max_skew, desired_skew, skew; + + if (time_state->enter_time) { + max_skew = (time_state->exit_time - time_state->enter_time) / 10; + } else { + max_skew = 0; } -#ifndef CONFIG_TIME_HIDE_VM_COST - // XXX This should turn into a target offset we want to move towards XXX - time_state->guest_host_offset = - (sint64_t)guest_time - (sint64_t)host_time; -#endif + desired_skew = target_guest_time - guest_time; + skew = desired_skew > max_skew ? max_skew : desired_skew; +/* PrintDebug("Guest %llu cycles behind where it should be.\n", + desired_skew); + PrintDebug("Limit on forward skew is %llu. Skewing forward %llu.\n", + max_skew, skew); */ + + v3_offset_time(info, skew); } - + return 0; } +/* Called immediately upon entry in the the VMM */ int -v3_pause_time( struct guest_info * info ) +v3_time_exit_vm( struct guest_info * info ) { struct vm_time * time_state = &(info->time_state); - if (time_state->pause_time == 0) { - time_state->pause_time = v3_get_host_time(time_state); -// PrintDebug("Pausing at host time %llu.\n", time_state->pause_time); - } else { - PrintError("Palacios timekeeping paused when already paused.\n"); - } + + time_state->exit_time = v3_get_host_time(time_state); + return 0; } +/* Called immediately prior to entry to the VM */ int -v3_restart_time( struct guest_info * info ) +v3_time_enter_vm( struct guest_info * info ) { struct vm_time * time_state = &(info->time_state); + uint64_t guest_time, host_time; - if (time_state->pause_time) { - sint64_t pause_diff = (v3_get_host_time(time_state) - time_state->pause_time); - time_state->guest_host_offset -= pause_diff; - time_state->pause_time = 0; -// PrintDebug("Resuming time after %lld cycles with offset %lld.\n", pause_diff, time_state->guest_host_offset); - } else { - PrintError( "Palacios time keeping restarted when not paused."); - } + guest_time = v3_get_guest_time(time_state); + host_time = v3_get_host_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; return 0; } -int v3_offset_time( struct guest_info * info, sint64_t offset ) -{ - struct vm_time * time_state = &(info->time_state); -// PrintDebug("Adding additional offset of %lld to guest time.\n", offset); - time_state->guest_host_offset += offset; - return 0; -} + struct v3_timer * v3_add_timer(struct guest_info * info, struct v3_timer_ops * ops, @@ -206,9 +233,6 @@ 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; - // PrintDebug("Updating timer for %lld elapsed cycles (pt=%llu, offset=%lld).\n", - // cycles, time_state->pause_time, time_state->guest_host_offset); - 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); } @@ -225,8 +249,10 @@ void v3_update_timers(struct guest_info * info) { int v3_rdtsc(struct guest_info * info) { uint64_t tscval = v3_get_guest_tsc(&info->time_state); + info->vm_regs.rdx = tscval >> 32; info->vm_regs.rax = tscval & 0xffffffffLL; + return 0; } @@ -377,8 +403,10 @@ void v3_init_time_core(struct guest_info * info) { info->cpu_id, time_state->guest_cpu_freq); } - if ((khz == NULL) || (time_state->guest_cpu_freq <= 0) - || (time_state->guest_cpu_freq > time_state->host_cpu_freq)) { + if ( (khz == NULL) || + (time_state->guest_cpu_freq <= 0) || + (time_state->guest_cpu_freq > time_state->host_cpu_freq) ) { + time_state->guest_cpu_freq = time_state->host_cpu_freq; } @@ -397,8 +425,6 @@ void v3_init_time_core(struct guest_info * info) { time_state->tsc_aux.lo = 0; time_state->tsc_aux.hi = 0; - - } @@ -412,9 +438,3 @@ void v3_deinit_time_core(struct guest_info * core) { } } - - - - - -