From: Marcelo Tosatti <mtosa...@redhat.com>
kvmclock should not count while vm is paused, because:
1) if the vm is paused for long periods, timekeeping
math can overflow while converting the (large) clocksource
delta to nanoseconds.
2) Users rely on CLOCK_MONOTONIC to count run time, that is,
time which OS has been in a runnable state (see CLOCK_BOOTTIME).
Change kvmclock driver so as to save clock value when vm transitions
from runnable to stopped state, and to restore clock value from stopped
to runnable transition.
Cc: qemu-sta...@nongnu.org
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
Signed-off-by: Gleb Natapov <g...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
(cherry picked from commit 00f4d64ee76e873be881a82d893a591487aa7950)
Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
---
hw/i386/kvm/clock.c | 64 ++++++++++++++++++++++++---------------------------
1 file changed, 30 insertions(+), 34 deletions(-)
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 87d4d0f..98e5ca5 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -28,38 +28,6 @@ typedef struct KVMClockState {
bool clock_valid;
} KVMClockState;
-static void kvmclock_pre_save(void *opaque)
-{
- KVMClockState *s = opaque;
- struct kvm_clock_data data;
- int ret;
-
- if (s->clock_valid) {
- return;
- }
- ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
- if (ret < 0) {
- fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
- data.clock = 0;
- }
- s->clock = data.clock;
- /*
- * If the VM is stopped, declare the clock state valid to avoid re-reading
- * it on next vmsave (which would return a different value). Will be reset
- * when the VM is continued.
- */
- s->clock_valid = !runstate_is_running();
-}
-
-static int kvmclock_post_load(void *opaque, int version_id)
-{
- KVMClockState *s = opaque;
- struct kvm_clock_data data;
-
- data.clock = s->clock;
- data.flags = 0;
- return kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
-}
static void kvmclock_vm_state_change(void *opaque, int running,
RunState state)
@@ -70,8 +38,18 @@ static void kvmclock_vm_state_change(void *opaque, int
running,
int ret;
if (running) {
+ struct kvm_clock_data data;
+
s->clock_valid = false;
+ data.clock = s->clock;
+ data.flags = 0;
+ ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
+ if (ret < 0) {
+ fprintf(stderr, "KVM_SET_CLOCK failed: %s\n", strerror(ret));
+ abort();
+ }
+
if (!cap_clock_ctrl) {
return;
}
@@ -84,6 +62,26 @@ static void kvmclock_vm_state_change(void *opaque, int
running,
return;
}
}
+ } else {
+ struct kvm_clock_data data;
+ int ret;
+
+ if (s->clock_valid) {
+ return;
+ }
+ ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data);
+ if (ret < 0) {
+ fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));
+ abort();
+ }
+ s->clock = data.clock;
+
+ /*
+ * If the VM is stopped, declare the clock state valid to
+ * avoid re-reading it on next vmsave (which would return
+ * a different value). Will be reset when the VM is continued.
+ */
+ s->clock_valid = true;
}
}
@@ -100,8 +98,6 @@ static const VMStateDescription kvmclock_vmsd = {
.version_id = 1,
.minimum_version_id = 1,
.minimum_version_id_old = 1,
- .pre_save = kvmclock_pre_save,
- .post_load = kvmclock_post_load,
.fields = (VMStateField[]) {
VMSTATE_UINT64(clock, KVMClockState),
VMSTATE_END_OF_LIST()
--
1.7.9.5
