-#include "palacios/vmm_time.h"
-#include "palacios/vmm.h"
+/*
+ * This file is part of the Palacios Virtual Machine Monitor developed
+ * by the V3VEE Project with funding from the United States National
+ * Science Foundation and the Department of Energy.
+ *
+ * The V3VEE Project is a joint project between Northwestern University
+ * and the University of New Mexico. You can find out more at
+ * http://www.v3vee.org
+ *
+ * Copyright (c) 2008, Jack Lange <jarusl@cs.northwestern.edu>
+ * Copyright (c) 2008, The V3VEE Project <http://www.v3vee.org>
+ * All rights reserved.
+ *
+ * Author: Jack Lange <jarusl@cs.northwestern.edu>
+ * Patrick G. Bridges <bridges@cs.unm.edu>
+ *
+ * This is free software. You are permitted to use,
+ * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
+ */
+#include <palacios/vmm_time.h>
+#include <palacios/vmm.h>
+#include <palacios/vm_guest.h>
-void v3_init_time(struct vm_time * time_state) {
- ullong_t cpu_khz = 0;
+#ifndef CONFIG_DEBUG_TIME
+#undef PrintDebug
+#define PrintDebug(fmt, args...)
+#endif
- V3_CPU_KHZ(cpu_khz);
- time_state->cpu_freq = cpu_khz;
+/* Overview
+ *
+ * Time handling in VMMs is challenging, and Palacios uses the highest
+ * resolution, lowest overhead timer on modern CPUs that it can - the
+ * processor timestamp counter (TSC). Note that on somewhat old processors
+ * this can be problematic; in particular, older AMD processors did not
+ * have a constant rate timestamp counter in the face of power management
+ * events. However, the latest Intel and AMD CPUs all do (should...) have a
+ * constant rate TSC, and Palacios relies on this fact.
+ *
+ * Basically, Palacios keeps track of three quantities as it runs to manage
+ * 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
+ * (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.
+ *
+ * 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).
+ *
+ *
+ *
+ */
- PrintDebug("CPU KHZ = HI=%x LO=%x\n", (uint_t)(cpu_khz >> 32), (uint_t)cpu_khz);
-
- time_state->guest_tsc = 0;
- time_state->cached_host_tsc = 0;
- time_state->pending_cycles = 0;
-
- INIT_LIST_HEAD(&(time_state->timers));
- time_state->num_timers = 0;
+
+static int handle_cpufreq_hcall(struct guest_info * info, uint_t hcall_id, void * priv_data) {
+ struct vm_time * time_state = &(info->time_state);
+
+ info->vm_regs.rbx = time_state->guest_cpu_freq;
+
+ PrintDebug("Guest request cpu frequency: return %ld\n", (long)info->vm_regs.rbx);
+
+ return 0;
}
-int v3_add_timer(struct guest_info * info, struct vm_timer_ops * ops, void * private_data) {
- // V3_Malloc
- /*
- list_add(&(timer->timer_link), &(info->time_state.timers));
- info->time_state.num_timers++;
- */
- return 0;
+int v3_start_time(struct guest_info * info) {
+ /* We start running with guest_time == host_time */
+ uint64_t t = v3_get_host_time(&info->time_state);
+
+ PrintDebug("Starting initial guest time as %llu\n", t);
+ info->time_state.last_update = t;
+ info->time_state.initial_time = t;
+ info->yield_start_cycle = t;
+ return 0;
}
-int remove_timer(struct guest_info * info, struct vm_timer * timer) {
- list_del(&(timer->timer_link));
- info->time_state.num_timers--;
+// 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) {
+ struct vm_time * time_state = &(info->time_state);
+ if (time_state->host_cpu_freq == time_state->guest_cpu_freq) {
+ time_state->guest_host_offset = 0;
+ } else {
+ uint64_t guest_time, host_time, target_host_time;
+ guest_time = v3_get_guest_time(time_state);
+ host_time = v3_get_host_time(time_state);
+ target_host_time = (host_time - time_state->initial_time) *
+ time_state->host_cpu_freq / time_state->guest_cpu_freq;
+ while (host_time < target_host_time) {
+ v3_yield(info);
+ host_time = v3_get_host_time(time_state);
+ }
+ time_state->guest_host_offset = guest_time - host_time;
- return 0;
+ }
+ 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));
+ V3_ASSERT(timer != NULL);
+
+ timer->ops = ops;
+ timer->private_data = private_data;
-void update_timers(struct guest_info * info) {
- struct vm_timer * tmp_timer;
-
- list_for_each_entry(tmp_timer, &(info->time_state.timers), timer_link) {
- tmp_timer->ops.update_time(info->time_state.pending_cycles, info->time_state.cpu_freq, tmp_timer->private_data);
- }
+ list_add(&(timer->timer_link), &(info->time_state.timers));
+ info->time_state.num_timers++;
+
+ return 0;
+}
+
+int v3_remove_timer(struct guest_info * info, struct vm_timer * timer) {
+ list_del(&(timer->timer_link));
+ info->time_state.num_timers--;
+
+ V3_Free(timer);
+ return 0;
+}
+
+void v3_update_timers(struct guest_info * info) {
+ struct vm_timer * tmp_timer;
+ uint64_t old_time = info->time_state.last_update;
+ uint64_t cycles;
+
+ info->time_state.last_update = v3_get_guest_time(&info->time_state);
+ cycles = info->time_state.last_update - old_time;
+
+ list_for_each_entry(tmp_timer, &(info->time_state.timers), timer_link) {
+ tmp_timer->ops->update_timer(info, cycles, info->time_state.guest_cpu_freq, tmp_timer->private_data);
+ }
+}
+/*
+ * 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.
+ */
- info->time_state.pending_cycles = 0;
+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;
}
+
+int v3_handle_rdtsc(struct guest_info * info) {
+ v3_rdtsc(info);
+
+ info->vm_regs.rax &= 0x00000000ffffffffLL;
+ info->vm_regs.rdx &= 0x00000000ffffffffLL;
+
+ info->rip += 2;
+
+ return 0;
+}
+
+int v3_rdtscp(struct guest_info * info) {
+ int ret;
+ /* First get the MSR value that we need. It's safe to futz with
+ * 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;
+ 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 */
+ ret = v3_rdtsc(info);
+ if (ret) return ret;
+
+ return 0;
+}
+
+
+int v3_handle_rdtscp(struct guest_info * info) {
+
+ v3_rdtscp(info);
+
+ info->vm_regs.rax &= 0x00000000ffffffffLL;
+ info->vm_regs.rcx &= 0x00000000ffffffffLL;
+ info->vm_regs.rdx &= 0x00000000ffffffffLL;
+
+ info->rip += 3;
+
+ return 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;
+
+ return 0;
+}
+
+static int tsc_aux_msr_write_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);
+ time_state->tsc_aux.lo = msr_val.lo;
+ time_state->tsc_aux.hi = msr_val.hi;
+
+ return 0;
+}
+
+static int tsc_msr_read_hook(struct guest_info *info, uint_t msr_num,
+ struct v3_msr *msr_val, void *priv) {
+ 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;
+
+ return 0;
+}
+
+static int tsc_msr_write_hook(struct guest_info *info, uint_t msr_num,
+ 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;
+}
+
+static int init_vm_time(struct v3_vm_info *vm_info) {
+ int ret;
+
+ PrintDebug("Installing TSC MSR hook.\n");
+ ret = v3_hook_msr(vm_info, TSC_MSR,
+ tsc_msr_read_hook, tsc_msr_write_hook, NULL);
+
+ 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,
+ tsc_aux_msr_write_hook, NULL);
+ if (ret) return ret;
+
+ PrintDebug("Registering TIME_CPUFREQ hypercall.\n");
+ ret = v3_register_hypercall(vm_info, TIME_CPUFREQ_HCALL,
+ handle_cpufreq_hcall, NULL);
+ return ret;
+}
+
+void v3_init_time(struct guest_info * info) {
+ struct vm_time * time_state = &(info->time_state);
+ static int one_time = 0;
+
+ time_state->host_cpu_freq = V3_CPU_KHZ();
+ time_state->guest_cpu_freq = V3_CPU_KHZ();
+
+ time_state->initial_time = 0;
+ time_state->last_update = 0;
+ time_state->guest_host_offset = 0;
+ time_state->tsc_guest_offset = 0;
+
+ INIT_LIST_HEAD(&(time_state->timers));
+ time_state->num_timers = 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;
+ }
+}
+
+
+
+
+
+