From: Patrick G. Bridges <bridges@cs.unm.edu>
Date: Tue, 15 May 2012 18:16:41 +0000 (-0600)
Subject: Added TSC passthrough specification to time handling
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=commitdiff_plain;h=5257ce9721525328a025a443ac086e34e0dc6441;p=palacios.git

Added TSC passthrough specification to time handling
---

diff --git a/palacios/include/palacios/vmm_time.h b/palacios/include/palacios/vmm_time.h
index 4a35cc2..9293329 100644
--- a/palacios/include/palacios/vmm_time.h
+++ b/palacios/include/palacios/vmm_time.h
@@ -37,7 +37,8 @@ struct v3_time {
     int flags;
     uint32_t td_num, td_denom; 
 };
-#define V3_TIME_SLAVE_HOST (1 << 1)
+#define V3_TIME_SLAVE_HOST (1 << 0)
+#define V3_TIME_TSC_PASSTHROUGH (1 << 1)
 
 /* Per-core time information */
 struct vm_core_time {
@@ -65,8 +66,9 @@ struct vm_core_time {
 
 };
 
-#define VM_TIME_TRAP_RDTSC (1 << 0)
-#define VM_TIME_SLAVE_HOST (1 << 1)
+#define VM_TIME_SLAVE_HOST (1 << 0)
+#define VM_TIME_TSC_PASSTHROUGH (1 << 1)
+#define VM_TIME_TRAP_RDTSC (1 << 2)
 
 struct v3_timer_ops {
     void (*update_timer)(struct guest_info * info, ullong_t cpu_cycles, ullong_t cpu_freq, void * priv_data);
@@ -120,7 +122,7 @@ static inline uint64_t v3_get_guest_tsc(struct vm_core_time *t) {
 // Returns offset of guest TSC from host TSC
 static inline sint64_t v3_tsc_host_offset(struct vm_core_time *time_state) {
     uint64_t host_time = v3_get_host_time(time_state);
-    return ((sint64_t)time_state->guest_cycles - (sint64_t)host_time) + time_state->tsc_guest_offset;
+    return (sint64_t)v3_get_guest_tsc(time_state) - (sint64_t)host_time;
 }
 
 // Functions for handling exits on the TSC when fully virtualizing 
diff --git a/palacios/src/palacios/svm.c b/palacios/src/palacios/svm.c
index 9d17949..4d148e9 100644
--- a/palacios/src/palacios/svm.c
+++ b/palacios/src/palacios/svm.c
@@ -529,7 +529,11 @@ v3_svm_config_tsc_virtualization(struct guest_info * info) {
     } else {
 	ctrl_area->instrs.RDTSC = 0;
 	ctrl_area->svm_instrs.RDTSCP = 0;
-        ctrl_area->TSC_OFFSET = v3_tsc_host_offset(&info->time_state);
+	if (info->time_state.flags & VM_TIME_TSC_PASSTHROUGH) {
+        	ctrl_area->TSC_OFFSET = 0;
+	} else {
+        	ctrl_area->TSC_OFFSET = v3_tsc_host_offset(&info->time_state);
+	}
     }
     return 0;
 }
diff --git a/palacios/src/palacios/vmm_time.c b/palacios/src/palacios/vmm_time.c
index ce89b21..5b3bfe7 100644
--- a/palacios/src/palacios/vmm_time.c
+++ b/palacios/src/palacios/vmm_time.c
@@ -314,7 +314,7 @@ static int tsc_msr_write_hook(struct guest_info *info, uint_t msr_num,
 
 static int
 handle_time_configuration(struct v3_vm_info * vm, v3_cfg_tree_t *cfg) {
-    char *source, *dilation;
+    char *source, *dilation, *tsc;
 
     vm->time_state.flags = V3_TIME_SLAVE_HOST;
     vm->time_state.td_num = vm->time_state.td_denom = 1;
@@ -332,6 +332,19 @@ handle_time_configuration(struct v3_vm_info * vm, v3_cfg_tree_t *cfg) {
 	}
     }
 
+    // Should we make a separate TSC device that handles this sort of thing?
+    tsc = v3_cfg_val(cfg, "tsc");
+    if (tsc) {
+	if (strcasecmp(tsc, "host") == 0) {
+	    if (!(vm->time_state.flags & V3_TIME_SLAVE_HOST)) {
+		PrintError("WARNING: Guest TSC set to passthrough host TSC, but guest time not slaved to host time.");
+	    }
+	    vm->time_state.flags |= V3_TIME_TSC_PASSTHROUGH;
+	} else if (strcasecmp(source, "guest") != 0) {
+	    PrintError("ERROR: Unknown TSC configuration in time configuration.\n");
+	}
+    }
+
     dilation = v3_cfg_val(cfg, "dilation");
     if (dilation) {
         if (!(vm->time_state.flags & VM_TIME_SLAVE_HOST)) {
@@ -450,10 +463,18 @@ void v3_init_time_core(struct guest_info * info) {
     if (info->vm_info->time_state.flags & V3_TIME_SLAVE_HOST) {
 	time_state->flags |= VM_TIME_SLAVE_HOST;
     }
+    if (info->vm_info->time_state.flags & V3_TIME_TSC_PASSTHROUGH) {
+	time_state->flags |= VM_TIME_TSC_PASSTHROUGH;
+    }
+
     if ((time_state->clock_ratio_denom != 1) ||
 	(time_state->clock_ratio_num != 1) ||
 	(info->vm_info->time_state.td_num != 1) || 
 	(info->vm_info->time_state.td_denom != 1)) { 
+	if (time_state->flags | VM_TIME_TSC_PASSTHROUGH) {
+	    PrintError("WARNING: Cannot use reqested passthrough TSC with clock or time modification also requested.\n");
+	    time_state->flags &= ~VM_TIME_TSC_PASSTHROUGH;
+	}
 	time_state->flags |= VM_TIME_TRAP_RDTSC;
     }
 
@@ -466,9 +487,11 @@ void v3_init_time_core(struct guest_info * info) {
 	       info->vm_info->time_state.td_denom, 
 	       time_state->clock_ratio_num, time_state->clock_ratio_denom,
 	       time_state->ipc_ratio_num, time_state->ipc_ratio_denom);
-    PrintDebug("    source = %s, rdtsc trapping = %s\n", 
+    PrintDebug("    time source = %s, tsc handling =  %s\n", 
 	       (time_state->flags & VM_TIME_SLAVE_HOST) ? "host" : "none",
-	       (time_state->flags & VM_TIME_TRAP_RDTSC) ? "true" : "false");
+	       (time_state->flags & VM_TIME_TSC_PASSTHROUGH) ? "passthrough" 
+	           : (time_state->flags & VM_TIME_TRAP_RDTSC) ? "trapping" 
+		       : "offsettting");
 
     time_state->guest_cycles = 0;
     time_state->tsc_guest_offset = 0;
diff --git a/palacios/src/palacios/vmx.c b/palacios/src/palacios/vmx.c
index b29673f..6fa3bed 100644
--- a/palacios/src/palacios/vmx.c
+++ b/palacios/src/palacios/vmx.c
@@ -886,7 +886,11 @@ v3_vmx_config_tsc_virtualization(struct guest_info * info) {
 	    check_vmcs_write(VMCS_PROC_CTRLS, vmx_info->pri_proc_ctrls.value);
 	}
 
-        tsc_offset = v3_tsc_host_offset(&info->time_state);
+	if (info->time_state.flags & VM_TIME_TSC_PASSTHROUGH) {
+	    tsc_offset = 0;
+	} else {
+            tsc_offset = v3_tsc_host_offset(&info->time_state);
+	}
         tsc_offset_high = (uint32_t)(( tsc_offset >> 32) & 0xffffffff);
         tsc_offset_low = (uint32_t)(tsc_offset & 0xffffffff);