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[Qemu-devel] [PATCH resend] kvmclock: fix clock_is_reliable on migration
From: |
Michael Chapman |
Subject: |
[Qemu-devel] [PATCH resend] kvmclock: fix clock_is_reliable on migration from QEMU < 2.9 |
Date: |
Fri, 6 Apr 2018 15:34:06 +1000 |
When migrating from a pre-2.9 QEMU, no clock_is_reliable flag is
transferred. We should assume that the source host has an unreliable
KVM_GET_CLOCK, rather than using whatever was determined locally, to
ensure that any drift from the TSC-based value calculated by the guest
is corrected.
Signed-off-by: Michael Chapman <address@hidden>
---
Resent due to missing CCs.
hw/i386/kvm/clock.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 1707434db3..7dac319403 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -241,6 +241,19 @@ static const VMStateDescription
kvmclock_reliable_get_clock = {
}
};
+/*
+ * When migrating, assume the source has an unreliable
+ * KVM_GET_CLOCK unless told otherwise.
+ */
+static int kvmclock_pre_load(void *opaque)
+{
+ KVMClockState *s = opaque;
+
+ s->clock_is_reliable = false;
+
+ return 0;
+}
+
/*
* When migrating, read the clock just before migration,
* so that the guest clock counts during the events
@@ -268,6 +281,7 @@ static const VMStateDescription kvmclock_vmsd = {
.name = "kvmclock",
.version_id = 1,
.minimum_version_id = 1,
+ .pre_load = kvmclock_pre_load,
.pre_save = kvmclock_pre_save,
.fields = (VMStateField[]) {
VMSTATE_UINT64(clock, KVMClockState),
--
2.14.3
- [Qemu-devel] [PATCH resend] kvmclock: fix clock_is_reliable on migration from QEMU < 2.9,
Michael Chapman <=