1 files changed, 34 insertions, 18 deletions

diff --git a/hw/kvm/i8254.c b/hw/kvm/i8254.c
index c5d3711a0..53d13e312 100644
--- a/hw/kvm/i8254.c
+++ b/hw/kvm/i8254.c
@@ -35,7 +35,8 @@
 typedef struct KVMPITState {
     PITCommonState pit;
     LostTickPolicy lost_tick_policy;
-    bool state_valid;
+    bool vm_stopped;
+    int64_t kernel_clock_offset;
 } KVMPITState;
 
 static int64_t abs64(int64_t v)
@@ -43,19 +44,11 @@ static int64_t abs64(int64_t v)
     return v < 0 ? -v : v;
 }
 
-static void kvm_pit_get(PITCommonState *pit)
+static void kvm_pit_update_clock_offset(KVMPITState *s)
 {
-    KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit);
-    struct kvm_pit_state2 kpit;
-    struct kvm_pit_channel_state *kchan;
-    struct PITChannelState *sc;
     int64_t offset, clock_offset;
     struct timespec ts;
-    int i, ret;
-
-    if (s->state_valid) {
-        return;
-    }
+    int i;
 
     /*
      * Measure the delta between CLOCK_MONOTONIC, the base used for
@@ -72,6 +65,21 @@ static void kvm_pit_get(PITCommonState *pit)
             clock_offset = offset;
         }
     }
+    s->kernel_clock_offset = clock_offset;
+}
+
+static void kvm_pit_get(PITCommonState *pit)
+{
+    KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit);
+    struct kvm_pit_state2 kpit;
+    struct kvm_pit_channel_state *kchan;
+    struct PITChannelState *sc;
+    int i, ret;
+
+    /* No need to re-read the state if VM is stopped. */
+    if (s->vm_stopped) {
+        return;
+    }
 
     if (kvm_has_pit_state2()) {
         ret = kvm_vm_ioctl(kvm_state, KVM_GET_PIT2, &kpit);
@@ -106,7 +114,7 @@ static void kvm_pit_get(PITCommonState *pit)
         sc->mode = kchan->mode;
         sc->bcd = kchan->bcd;
         sc->gate = kchan->gate;
-        sc->count_load_time = kchan->count_load_time + clock_offset;
+        sc->count_load_time = kchan->count_load_time + s->kernel_clock_offset;
     }
 
     sc = &pit->channels[0];
@@ -114,17 +122,23 @@ static void kvm_pit_get(PITCommonState *pit)
         pit_get_next_transition_time(sc, sc->count_load_time);
 }
 
-static void kvm_pit_put(PITCommonState *s)
+static void kvm_pit_put(PITCommonState *pit)
 {
+    KVMPITState *s = DO_UPCAST(KVMPITState, pit, pit);
     struct kvm_pit_state2 kpit;
     struct kvm_pit_channel_state *kchan;
     struct PITChannelState *sc;
     int i, ret;
 
-    kpit.flags = s->channels[0].irq_disabled ? KVM_PIT_FLAGS_HPET_LEGACY : 0;
+    /* The offset keeps changing as long as the VM is stopped. */
+    if (s->vm_stopped) {
+        kvm_pit_update_clock_offset(s);
+    }
+
+    kpit.flags = pit->channels[0].irq_disabled ? KVM_PIT_FLAGS_HPET_LEGACY : 0;
     for (i = 0; i < 3; i++) {
         kchan = &kpit.channels[i];
-        sc = &s->channels[i];
+        sc = &pit->channels[i];
         kchan->count = sc->count;
         kchan->latched_count = sc->latched_count;
         kchan->count_latched = sc->count_latched;
@@ -137,7 +151,7 @@ static void kvm_pit_put(PITCommonState *s)
         kchan->mode = sc->mode;
         kchan->bcd = sc->bcd;
         kchan->gate = sc->gate;
-        kchan->count_load_time = sc->count_load_time;
+        kchan->count_load_time = sc->count_load_time - s->kernel_clock_offset;
     }
 
     ret = kvm_vm_ioctl(kvm_state,
@@ -211,10 +225,12 @@ static void kvm_pit_vm_state_change(void *opaque, int running,
     KVMPITState *s = opaque;
 
     if (running) {
-        s->state_valid = false;
+        kvm_pit_update_clock_offset(s);
+        s->vm_stopped = false;
     } else {
+        kvm_pit_update_clock_offset(s);
         kvm_pit_get(&s->pit);
-        s->state_valid = true;
+        s->vm_stopped = true;
     }
 }