X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=blobdiff_plain;f=palacios%2Fsrc%2Fpalacios%2Fvmm_time.c;h=51ac5a76e3a538c91506a3af39ad0cf6c76c3ab5;hb=7229981629c6baa0afb61cc99cfcf6dd029c9c93;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..51ac5a7 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 <palacios/vmm_time.h>
 #include <palacios/vmm.h>
+#include <palacios/vmm_time.h>
 #include <palacios/vm_guest.h>
 
-#ifndef CONFIG_DEBUG_TIME
+#ifndef V3_CONFIG_DEBUG_TIME
 #undef PrintDebug
 #define PrintDebug(fmt, args...)
 #endif
@@ -41,15 +41,14 @@
  * 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 using an offsets from (1) above.
+ *     time in the guest. This is stored as an absolute number of cycles elapsed
+ *     and is updated on guest entry and exit; it can also be updated explicitly
+ *     in the monitor at times
  * (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).
@@ -58,7 +57,7 @@
  * (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 
+ *     simulated feature and a real implementation of that feature, making time
  *     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.
@@ -66,11 +65,17 @@
  *     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.
+ *
+ * (2) Look more into sychronizing the offsets *across* virtual and physical 
+ *     cores so that multicore guests stay mostly in sync.
+ *
+ * (3) Look into using the AMD TSC multiplier feature and adding explicit time
+ *     dilation support to time handling.
  */
 
 
 static int handle_cpufreq_hcall(struct guest_info * info, uint_t hcall_id, void * priv_data) {
-    struct vm_time * time_state = &(info->time_state);
+    struct vm_core_time * time_state = &(info->time_state);
 
     info->vm_regs.rbx = time_state->guest_cpu_freq;
 
@@ -85,87 +90,93 @@ 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);
-#ifdef CONFIG_TIME_HIDE_VM_COST
-    info->time_state.pause_time = t; 
-#else
-    info->time_state.pause_time = 0; 
-#endif
-    info->time_state.last_update = t;
-    info->time_state.initial_time = t;
+    info->time_state.vm_enter_host_time = 0;
+    info->time_state.vm_pause_host_time = t; 
+    info->time_state.initial_host_time = t;
     info->yield_start_cycle = t;
+
+    info->time_state.last_update = 0;
+    info->time_state.guest_cycles = 0;
+    PrintDebug("Starting time for core %d at host time %llu/guest time %llu.\n",
+	       info->vcpu_id, t, info->time_state.guest_cycles); 
+    v3_yield(info);
     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) {
-    struct vm_time * time_state = &(info->time_state);
+int v3_offset_time( struct guest_info * info, sint64_t offset )
+{
+    struct vm_core_time * time_state = &(info->time_state);
+    if (info->vm_info->time_state.follow_host_time) {
+	PrintError("Cannot offset guest time passage while slaved to host clock.\n");
+	return 1;
+    } else {
+        time_state->guest_cycles += offset;
+    }
+    return 0;
+}
 
-    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;
+int v3_skip_time(struct guest_info * info) {
+    if (info->vm_info->time_state.follow_host_time) {
+	PrintError("Cannot skip guest time passage while slaved to host clock.\n");
+	return 1;
+    } else {
+        info->time_state.vm_pause_host_time = v3_get_host_time(&info->time_state);
+    }
+    return 0;
+}
 
-	guest_time = v3_get_guest_time(time_state);
+static sint64_t host_to_guest_cycles(struct guest_info * info, sint64_t host_cycles) {
+    return (host_cycles * info->time_state.clock_ratio_num) / info->time_state.clock_ratio_denom;
+}
 
-	/* 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;
+int v3_time_advance_cycles(struct guest_info * info, uint64_t *host_cycles)
+{
+    uint64_t t = v3_get_host_time(&info->time_state);
 
-	/* Yield until that host time is reached */
-	host_time = v3_get_host_time(time_state);
+    info->time_state.vm_pause_host_time = t;
 
-	while (host_time < target_host_time) {
-	    v3_yield(info);
-	    host_time = v3_get_host_time(time_state);
-	}
+    if (info->vm_info->time_state.follow_host_time) {
+	/* How many guest cycles should have elapsed? */
+	sint64_t host_elapsed = t - info->time_state.initial_host_time;
+	sint64_t guest_elapsed = host_to_guest_cycles(info, host_elapsed);
 
-	// 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;
-    }
+	info->time_state.guest_cycles = guest_elapsed;
+    } else {
+        uint64_t guest_cycles;
+	if (*host_cycles) {
+	    guest_cycles = host_to_guest_cycles(info, *host_cycles);
+	} else {
+	    guest_cycles = host_to_guest_cycles(info, (sint64_t)(t - info->time_state.vm_pause_host_time));
+	}
+        info->time_state.guest_cycles += guest_cycles;
+    } 
 
     return 0;
 }
 
+int v3_advance_time(struct guest_info * info) {
+    return v3_time_advance_cycles(info, NULL);
+}
+
+/* Called immediately upon entry in the the VMM */
 int 
-v3_pause_time( struct guest_info * info ) 
+v3_time_exit_vm( struct guest_info * info, uint64_t * host_cycles ) 
 {
-    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");
-    }
-    return 0;
+    return v3_time_advance_cycles(info, host_cycles);
 }
 
+/* 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.");
-    }
+    struct vm_core_time * time_state = &(info->time_state);
+    uint64_t host_time = v3_get_host_time(&info->time_state);
 
+    time_state->vm_enter_host_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, 
@@ -192,22 +203,26 @@ 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 vm_core_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 = 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);
+    if (cycles < 0) {
+	PrintError("Cycles appears to have rolled over - old time %lld, current time %lld.\n",
+		   old_time, time_state->last_update);
+	return;
+    }
 
+    PrintDebug("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);
     }
 }
 
+
 /* 
  * 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
@@ -219,14 +234,14 @@ 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;
@@ -277,7 +292,7 @@ int v3_handle_rdtscp(struct guest_info * info) {
 
 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);
+    struct vm_core_time * time_state = &(info->time_state);
 
     V3_ASSERT(msr_num == TSC_AUX_MSR);
 
@@ -289,7 +304,7 @@ static int tsc_aux_msr_read_hook(struct guest_info *info, uint_t msr_num,
 
 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);
+    struct vm_core_time * time_state = &(info->time_state);
 
     V3_ASSERT(msr_num == TSC_AUX_MSR);
 
@@ -313,14 +328,14 @@ static int tsc_msr_read_hook(struct guest_info *info, uint_t msr_num,
 
 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);
+    struct vm_core_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; 
+    time_state->tsc_guest_offset = (sint64_t)(new_tsc - guest_time); 
 
     return 0;
 }
@@ -349,6 +364,13 @@ int v3_init_time_vm(struct v3_vm_info * vm) {
     ret = v3_register_hypercall(vm, TIME_CPUFREQ_HCALL, 
 				handle_cpufreq_hcall, NULL);
 
+    vm->time_state.td_num = 1;
+    vm->time_state.td_denom = 1;
+    PrintDebug("Setting base time dilation factor to %d/%d.\n", 
+	       vm->time_state.td_num, vm->time_state.td_denom);
+
+    vm->time_state.follow_host_time = 1;
+    PrintDebug("Locking guest time to host time.\n");
     return ret;
 }
 
@@ -360,7 +382,7 @@ void v3_deinit_time_vm(struct v3_vm_info * vm) {
 }
 
 void v3_init_time_core(struct guest_info * info) {
-    struct vm_time * time_state = &(info->time_state);
+    struct vm_core_time * time_state = &(info->time_state);
     v3_cfg_tree_t * cfg_tree = info->core_cfg_data;
     char * khz = NULL;
 
@@ -369,36 +391,47 @@ 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, 
+    /* Compute these using the GCD() of the guest and host CPU freq.
+     * If the GCD is too small, make it "big enough" */
+    time_state->clock_ratio_num = 1;
+    time_state->clock_ratio_denom = 1;
+
+    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);
 
-    time_state->initial_time = 0;
-    time_state->last_update = 0;
-    time_state->guest_host_offset = 0;
+    time_state->guest_cycles = 0;
     time_state->tsc_guest_offset = 0;
+    time_state->last_update = 0;
+
+    time_state->initial_host_time = 0;
+    time_state->vm_enter_host_time = 0;
+    time_state->vm_pause_host_time = 0;
+
+    time_state->time_flags = 0; // XXX need to set trap TSC flag or not wisely
 
     INIT_LIST_HEAD(&(time_state->timers));
     time_state->num_timers = 0;
     
     time_state->tsc_aux.lo = 0;
     time_state->tsc_aux.hi = 0;
-
-
 }
 
 
 void v3_deinit_time_core(struct guest_info * core) {
-    struct vm_time * time_state = &(core->time_state);
+    struct vm_core_time * time_state = &(core->time_state);
     struct v3_timer * tmr = NULL;
     struct v3_timer * tmp = NULL;
 
@@ -407,9 +440,3 @@ void v3_deinit_time_core(struct guest_info * core) {
     }
 
 }
-
-
-
-
-
-