Time configuration parameters added. More time control code prototyped,

but no robust control in place yet.

diff --git a/Kconfig b/Kconfig
index 1049045..9092a67 100644 (file)
--- a/Kconfig
+++ b/Kconfig
@@ -189,7 +189,6 @@ endmenu
 source "Kconfig.stdlibs"
 
 
-
 menu "Virtual Paging"
 
 config SHADOW_PAGING
@@ -217,6 +216,38 @@ config DEBUG_SHDW_PG_VTLB
 endmenu
 
 
+menu "Time Management"
+
+
+config TIME_VIRTUALIZE_TSC
+       bool "Virtualize guest TSC"
+       default n
+       help
+           Virtualize the processor time stamp counter in the guest, 
+           generally increasing consistency between various time sources 
+           but also potentially making guest time run slightly slower
+           than real time.
+
+config TIME_VIRTUAL_TSC_CONTROL
+       bool "Adjust virtual TSC towards real time when possible"
+       default y
+       depends on TIME_VIRTUALIZE_TSC
+       help 
+           Enables control of TSC virtualization so that the TSC
+           attempts to catch up with real time when possible
+
+config TIME_MASK_OVERHEAD
+       bool "Hide virtualization overhead from guest timing"
+       default n
+       depends on TIME_VIRTUALIZE_TSC
+       help
+           Try to mask the overhead of virtualization from guests
+           by not including it in the time updates. Can dramatically
+           slow virtual time compared to real time if VIRTUAL_TSC_CONTROL
+           is not enabled.
+
+endmenu
+
 menu "Symbiotic Functions"
 
 config SYMBIOTIC

diff --git a/palacios/include/palacios/vmm_time.h b/palacios/include/palacios/vmm_time.h
index 3f6bbac..0a25833 100644 (file)
--- a/palacios/include/palacios/vmm_time.h
+++ b/palacios/include/palacios/vmm_time.h
@@ -31,14 +31,10 @@ struct guest_info;
 struct vm_time {
     uint32_t cpu_freq; // in kHZ
 
-    // Last time (in guest time) the timers were updated
-    uint64_t last_update;
-    
-    // Cache value to help calculate the guest_tsc
-    uint64_t pause_time;
-
-    // Offset of guest time from host time.
-    sint64_t host_offset;
+    uint64_t last_update;  // Last time (in guest time) the timers were updated
+    uint64_t pause_time;   // Cache value to help calculate the guest_tsc
+    sint64_t host_offset;  // Offset of guest time from host time.
+    sint64_t offset_sum;   // Sum of past and current host_offsets
 
     // Installed Timers 
     uint_t num_timers;
@@ -80,7 +76,8 @@ static inline uint64_t v3_get_host_time(struct vm_time *t) {
 }
 
 static inline uint64_t v3_get_guest_time(struct vm_time *t) {
-    return v3_get_host_time(t) + t->host_offset;
+    if (t->pause_time) return t->pause_time;
+    else return v3_get_host_time(t) + t->host_offset;
 }
 #endif // !__V3VEE__
 

diff --git a/palacios/src/palacios/svm.c b/palacios/src/palacios/svm.c
index 55e591e..dc2b660 100644 (file)
--- a/palacios/src/palacios/svm.c
+++ b/palacios/src/palacios/svm.c
@@ -471,14 +471,17 @@ int v3_svm_enter(struct guest_info * info) {
 
     v3_update_timers(info);
     v3_resume_time(info);
+
+#ifdef CONFIG_TIME_TSC_OFFSET
     guest_ctrl->TSC_OFFSET = info->time_state.host_offset;
+#endif
 
     //V3_Print("Calling v3_svm_launch\n");
 
     v3_svm_launch((vmcb_t *)V3_PAddr(info->vmm_data), &(info->vm_regs), (vmcb_t *)host_vmcbs[info->cpu_id]);
 
     v3_pause_time(info);
-#ifdef OPTION_TIME_MASK_OVERHEAD
+#ifdef CONFIG_TIME_MASK_OVERHEAD
     v3_offset_time(info, -SVM_ENTRY_OVERHEAD);
 #endif
 

diff --git a/palacios/src/palacios/vmm_time.c b/palacios/src/palacios/vmm_time.c
index 7814acb..e7d5cfe 100644 (file)
--- a/palacios/src/palacios/vmm_time.c
+++ b/palacios/src/palacios/vmm_time.c
@@ -47,7 +47,8 @@ void v3_init_time(struct guest_info * info) {
     time_state->pause_time = 0;
     time_state->last_update = 0;
     time_state->host_offset = 0;
-    
+    time_state->offset_sum = 0;
+
     INIT_LIST_HEAD(&(time_state->timers));
     time_state->num_timers = 0;
 
@@ -73,14 +74,43 @@ int v3_pause_time(struct guest_info * info) {
     return 0;
 }
 
+/* Use a control-theoretic approach, specifically a PI control approach,
+ * to adjust host_offset towards 0. Overall control documentation in 
+ * palacios/docs/time_control.tex Control parameters are P and I, 
+ * broken into rational numbers
+ */
+
+/* These numbers need to be actually determined by pole placement work. They're 
+ * just blind guesses for now, which is a really bad idea. :) */
+#define P_NUM 1
+#define P_DENOM 2
+#define I_NUM 1
+#define I_DENOM 20
+
+void adjust_time_offset(struct guest_info * info) {
+    /* Set point for control: Desired offset = 0; 
+     * Error = host_offset - 0 = host_offset */
+
+    sint64_t adjust;
+
+    /* Update the integral of the errror */
+    info->time_state.offset_sum += info->time_state.host_offset;
+    adjust = (P_NUM * info->time_state.host_offset) / P_DENOM +
+       (I_NUM * info->time_state.offset_sum) / I_DENOM;
+
+    /* We may want to constrain *adjust* because of
+     * resolution/accuracy constraints. Explore that later. */
+    info->time_state.host_offset -= adjust;
+    return;
+}
+
 int v3_resume_time(struct guest_info * info) {
     uint64_t t = v3_get_host_time(&info->time_state);
     V3_ASSERT(info->time_state.pause_time != 0);
     info->time_state.host_offset = 
        (sint64_t)info->time_state.pause_time - (sint64_t)t;
 #ifdef CONFIG_TIME_TSC_OFFSET_ADJUST
-    /* XXX Adjust host_offset towards zero based on resolution/accuracy
-     * constraints. */
+    adjust_time_offset(info);
 #endif
     info->time_state.pause_time = 0;
     PrintDebug("Time resumed paused at guest time as %llu "

diff --git a/palacios/src/palacios/vmx.c b/palacios/src/palacios/vmx.c
index 9a2e859..16fc5cd 100644 (file)
--- a/palacios/src/palacios/vmx.c
+++ b/palacios/src/palacios/vmx.c
@@ -225,6 +225,9 @@ static int init_vmcs_bios(struct guest_info * info, struct vmx_data * vmx_state)
     vmx_state->pri_proc_ctrls.invlpg_exit = 1;
     vmx_state->pri_proc_ctrls.use_msr_bitmap = 1;
     vmx_state->pri_proc_ctrls.pause_exit = 1;
+#ifdef CONFIG_TIME_TSC_OFFSET
+    vmx_state->pri_proc_ctrls.tsc_offset = 1;
+#endif
 
     vmx_ret |= check_vmcs_write(VMCS_IO_BITMAP_A_ADDR, (addr_t)V3_PAddr(info->vm_info->io_map.arch_data));
     vmx_ret |= check_vmcs_write(VMCS_IO_BITMAP_B_ADDR, 
@@ -696,7 +699,7 @@ int v3_vmx_enter(struct guest_info * info) {
     }
 
     v3_pause_time(info);
-#ifdef OPTION_TIME_MASK_OVERHEAD
+#ifdef CONFIG_TIME_MASK_OVERHEAD
     v3_offset_time(info, -VMX_ENTRY_OVERHEAD);
 #endif