X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=blobdiff_plain;f=palacios%2Fsrc%2Fpalacios%2Fvmm_time.c;h=2295b3fc90d8ac340ba93eef6dfbbacb10681bf0;hb=8a3dbb70c29175bad79764a0b2f3961b98138bb2;hp=1cb647839ee71069992a6936e9bd46cf08684df1;hpb=89034c39d340e3f6b24a8288ceeb506ddbdf7057;p=palacios.git diff --git a/palacios/src/palacios/vmm_time.c b/palacios/src/palacios/vmm_time.c index 1cb6478..2295b3f 100644 --- a/palacios/src/palacios/vmm_time.c +++ b/palacios/src/palacios/vmm_time.c @@ -18,11 +18,11 @@ * redistribute, and modify it as specified in the file "V3VEE_LICENSE". */ -#include #include +#include #include -#ifndef CONFIG_DEBUG_TIME +#ifndef V3_CONFIG_DEBUG_TIME #undef PrintDebug #define PrintDebug(fmt, args...) #endif @@ -86,86 +86,169 @@ 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; +} + +#ifdef V3_CONFIG_TIME_DILATION +static uint64_t compute_target_host_time(struct guest_info * info, uint64_t guest_time) +{ + struct vm_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_time * time_state = &(info->time_state); + uint64_t host_elapsed, desired_elapsed; - if (time_state->host_cpu_freq != time_state->guest_cpu_freq) { - uint64_t guest_time, guest_elapsed, desired_elapsed; - uint64_t host_time, target_host_time; + 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; - guest_time = v3_get_guest_time(time_state); + return 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; +} - /* Yield until that host time is reached */ +/* 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, 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_compute_guest_time(time_state, host_time); + 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); + } - while (host_time < target_host_time) { - v3_yield(info); - host_time = v3_get_host_time(time_state); + guest_time = v3_compute_guest_time(time_state, host_time); + + /* 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_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) / 10.0; + } else { + max_skew = 0; } - // This overrides any pause/unpause times because the difference - // is going to be too big for any pause/unpause the notice. - time_state->guest_host_offset = (sint64_t)guest_time - (sint64_t)host_time; + 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); } 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 -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); - - 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."); + uint64_t host_time; + + host_time = v3_get_host_time(time_state); + time_state->enter_time = host_time; +#ifdef V3_CONFIG_TIME_DILATION + { + uint64_t guest_time; + sint64_t offset; + guest_time = v3_compute_guest_time(time_state, host_time); + // XXX we probably want to use an inline function to do these + // time differences to deal with sign and overflow carefully + offset = (sint64_t)guest_time - (sint64_t)host_time; + PrintDebug("v3_time_enter_vm: guest time offset %lld from host time.\n", offset); + time_state->guest_host_offset = offset; } +#else + time_state->guest_host_offset = 0; +#endif 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, @@ -194,15 +277,14 @@ int v3_remove_timer(struct guest_info * info, struct v3_timer * timer) { void v3_update_timers(struct guest_info * info) { struct vm_time *time_state = &info->time_state; struct v3_timer * tmp_timer; - uint64_t old_time = info->time_state.last_update; sint64_t cycles; + uint64_t old_time = info->time_state.last_update; 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); + cycles = (sint64_t)(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); } @@ -219,14 +301,14 @@ 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); - PrintDebug("Returning %llu as TSC.\n", tscval); + info->vm_regs.rdx = tscval >> 32; info->vm_regs.rax = tscval & 0xffffffffLL; + return 0; } int v3_handle_rdtsc(struct guest_info * info) { - PrintDebug("Handling virtual RDTSC call.\n"); v3_rdtsc(info); info->vm_regs.rax &= 0x00000000ffffffffLL; @@ -369,16 +451,19 @@ 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) || (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; } - 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); @@ -392,8 +477,6 @@ void v3_init_time_core(struct guest_info * info) { time_state->tsc_aux.lo = 0; time_state->tsc_aux.hi = 0; - - } @@ -407,9 +490,3 @@ void v3_deinit_time_core(struct guest_info * core) { } } - - - - - -