[libvirt] [PATCH 3/3] qemu: fix broken RTC_CHANGE event when clock offset='variable'
Laine Stump
laine at laine.org
Wed May 21 13:16:31 UTC 2014
commit e31b5cf393857 attempted to fix libvirt's
VIR_DOMAIN_EVENT_ID_RTC_CHANGE, which is documentated to always
provide the new offset of the domain's real time clock from UTC. The
problem was that, in the case that qemu is provided with an "-rtc
base=x" where x is an absolute time (rather than "utc" or
"localtime"), the offset sent by qemu's RTC_CHANGE event is *not* the
new offset from UTC, but rather is the sum of all changes to the
domain's RTC since it was started with base=x.
So, despite what was said in commit e31b5cf393857, if we assume that
the original value stored in "adjustment" was the offset from UTC at
the time the domain was started, we can always determine the current
offset from UTC by simply adding the most recent (i.e. current) offset
from qemu to that original adjustment.
This patch accomplishes that by storing the initial adjustment in the
domain's status as "adjustment0". Each time a new RTC_CHANGE event is
received from qemu, we simply add adjustment0 to the value sent by
qemu, store that as the new adjustment, and forward that value on to
any event handler.
In the case of a clock that has offset='variable' basis='localtime',
the original adjustment in the XML will not have accounted for UTC
(i.e. it will be the offset of the domain's RTC from *local* time). So
although the value we want to save back into adjustment is still the
addition of "latest offset from qemu" + adjustment0, we still need to
adjust that value before sending to an event handler; in order to
convert the offset from localtime into offset from UTC, we need to add
the difference between UTC and localtime. (NB: to eliminate confusion
caused by a change in daylight savings status between when the domain
was started and when the RTC is changed, the offset from UTC to
localtime is retrieved only once when the domain is started, and saved
in the domain's status as "localtimeAdjustment0").
This patch (*not* e31b5cf393857, which should be reverted prior to
applying this patch) fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=964177
---
src/conf/domain_conf.c | 27 +++++++++++++++++++++++----
src/conf/domain_conf.h | 8 ++++++++
src/qemu/qemu_command.c | 13 +++++++++++++
src/qemu/qemu_process.c | 40 +++++++++++++++++++++++++++++++++++-----
4 files changed, 79 insertions(+), 9 deletions(-)
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index a7863c3..9c6c80c 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -99,6 +99,7 @@ typedef enum {
VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES = (1<<18),
VIR_DOMAIN_XML_INTERNAL_ALLOW_ROM = (1<<19),
VIR_DOMAIN_XML_INTERNAL_ALLOW_BOOT = (1<<20),
+ VIR_DOMAIN_XML_INTERNAL_CLOCK_ADJUST = (1<<21),
} virDomainXMLInternalFlags;
VIR_ENUM_IMPL(virDomainTaint, VIR_DOMAIN_TAINT_LAST,
@@ -12002,6 +12003,12 @@ virDomainDefParseXML(xmlDocPtr xml,
if (virXPathLongLong("number(./clock/@adjustment)", ctxt,
&def->clock.data.variable.adjustment) < 0)
def->clock.data.variable.adjustment = 0;
+ if (virXPathLongLong("number(./clock/@adjustment0)", ctxt,
+ &def->clock.data.variable.adjustment0) < 0)
+ def->clock.data.variable.adjustment0 = 0;
+ if (virXPathInt("number(./clock/@localtimeAdjustment0)", ctxt,
+ &def->clock.data.variable.localtimeAdjustment0) < 0)
+ def->clock.data.variable.localtimeAdjustment0 = 0;
tmp = virXPathString("string(./clock/@basis)", ctxt);
if (tmp) {
if ((def->clock.data.variable.basis = virDomainClockBasisTypeFromString(tmp)) < 0) {
@@ -17086,7 +17093,8 @@ virDomainResourceDefFormat(virBufferPtr buf,
verify(((VIR_DOMAIN_XML_INTERNAL_STATUS |
VIR_DOMAIN_XML_INTERNAL_ACTUAL_NET |
- VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES)
+ VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES |
+ VIR_DOMAIN_XML_INTERNAL_CLOCK_ADJUST)
& DUMPXML_FLAGS) == 0);
/* This internal version can accept VIR_DOMAIN_XML_INTERNAL_*,
@@ -17108,7 +17116,8 @@ virDomainDefFormatInternal(virDomainDefPtr def,
virCheckFlags(DUMPXML_FLAGS |
VIR_DOMAIN_XML_INTERNAL_STATUS |
VIR_DOMAIN_XML_INTERNAL_ACTUAL_NET |
- VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES,
+ VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES |
+ VIR_DOMAIN_XML_INTERNAL_CLOCK_ADJUST,
-1);
if (!(type = virDomainVirtTypeToString(def->virtType))) {
@@ -17642,6 +17651,14 @@ virDomainDefFormatInternal(virDomainDefPtr def,
virBufferAsprintf(buf, " adjustment='%lld' basis='%s'",
def->clock.data.variable.adjustment,
virDomainClockBasisTypeToString(def->clock.data.variable.basis));
+ if (flags & VIR_DOMAIN_XML_INTERNAL_CLOCK_ADJUST) {
+ if (def->clock.data.variable.adjustment0)
+ virBufferAsprintf(buf, " adjustment0='%lld'",
+ def->clock.data.variable.adjustment0);
+ if (def->clock.data.variable.localtimeAdjustment0)
+ virBufferAsprintf(buf, " localtimeAdjustment0='%d'",
+ def->clock.data.variable.localtimeAdjustment0);
+ }
break;
case VIR_DOMAIN_CLOCK_OFFSET_TIMEZONE:
virBufferEscapeString(buf, " timezone='%s'", def->clock.data.timezone);
@@ -18072,7 +18089,8 @@ virDomainSaveStatus(virDomainXMLOptionPtr xmlopt,
unsigned int flags = (VIR_DOMAIN_XML_SECURE |
VIR_DOMAIN_XML_INTERNAL_STATUS |
VIR_DOMAIN_XML_INTERNAL_ACTUAL_NET |
- VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES);
+ VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES |
+ VIR_DOMAIN_XML_INTERNAL_CLOCK_ADJUST);
int ret = -1;
char *xml;
@@ -18160,7 +18178,8 @@ virDomainObjListLoadStatus(virDomainObjListPtr doms,
if (!(obj = virDomainObjParseFile(statusFile, caps, xmlopt, expectedVirtTypes,
VIR_DOMAIN_XML_INTERNAL_STATUS |
VIR_DOMAIN_XML_INTERNAL_ACTUAL_NET |
- VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES)))
+ VIR_DOMAIN_XML_INTERNAL_PCI_ORIG_STATES |
+ VIR_DOMAIN_XML_INTERNAL_CLOCK_ADJUST)))
goto error;
virUUIDFormat(obj->def->uuid, uuidstr);
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 94285e3..6e45915 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -1727,6 +1727,14 @@ struct _virDomainClockDef {
struct {
long long adjustment;
int basis;
+
+ /* domain start-time adjustment. This is a
+ * private/internal read-only value that only exists when
+ * a domain is running, and only if the clock
+ * offset='variable'
+ */
+ long long adjustment0;
+ int localtimeAdjustment0;
} variable;
/* Timezone name, when
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 95f747f..ffec3ad 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -36,6 +36,7 @@
#include "virfile.h"
#include "virnetdev.h"
#include "virstring.h"
+#include "virtime.h"
#include "viruuid.h"
#include "c-ctype.h"
#include "domain_nwfilter.h"
@@ -5974,6 +5975,15 @@ qemuBuildClockArgStr(virDomainClockDefPtr def)
case VIR_DOMAIN_CLOCK_OFFSET_VARIABLE: {
time_t now = time(NULL);
struct tm nowbits;
+ time_t localOffset;
+
+ /* when an RTC_CHANGE event is received from qemu, we need to
+ * have the adjustment used at domain start time available to
+ * compute the new offset from UTC. As this new value is
+ * itself stored in def->data.variable.adjustment, we need to
+ * save a copy of it now.
+ */
+ def->data.variable.adjustment0 = def->data.variable.adjustment;
switch ((enum virDomainClockBasis) def->data.variable.basis) {
case VIR_DOMAIN_CLOCK_BASIS_UTC:
@@ -5983,6 +5993,9 @@ qemuBuildClockArgStr(virDomainClockDefPtr def)
case VIR_DOMAIN_CLOCK_BASIS_LOCALTIME:
now += def->data.variable.adjustment;
localtime_r(&now, &nowbits);
+ if (virTimeLocalOffsetFromUTC(&localOffset) < 0)
+ goto error;
+ def->data.variable.localtimeAdjustment0 = localOffset;
break;
case VIR_DOMAIN_CLOCK_BASIS_LAST:
break;
diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index 6dcb737..f618462 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -831,7 +831,6 @@ qemuProcessHandleResume(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
return 0;
}
-
static int
qemuProcessHandleRTCChange(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
virDomainObjPtr vm,
@@ -843,13 +842,44 @@ qemuProcessHandleRTCChange(qemuMonitorPtr mon ATTRIBUTE_UNUSED,
virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
virObjectLock(vm);
- event = virDomainEventRTCChangeNewFromObj(vm, offset);
- if (vm->def->clock.offset == VIR_DOMAIN_CLOCK_OFFSET_VARIABLE)
+ if (vm->def->clock.offset == VIR_DOMAIN_CLOCK_OFFSET_VARIABLE) {
+ /* when a basedate is manually given on the qemu commandline
+ * rather than simply "-rtc base=utc", the offset sent by qemu
+ * in this event is *not* the new offset from UTC, but is
+ * instead the new offset from the *original basedate* +
+ * uptime. For example, if the original offset was 3600 and
+ * the guest clock has been advanced by 10 seconds, qemu will
+ * send "10" in the event - this means that the new offset
+ * from UTC is 3610, *not* 10. If the guest clock is advanced
+ * by another 10 seconds, qemu will now send "20" - i.e. each
+ * event is the sum of the most recent change and all previous
+ * changes since the domain was started. Fortunately, we have
+ * saved the initial offset in "adjustment0", so to arrive at
+ * the proper new "adjustment", we just add the most recent
+ * offset to adjustment0.
+ */
+ offset += vm->def->clock.data.variable.adjustment0;
vm->def->clock.data.variable.adjustment = offset;
- if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)
- VIR_WARN("unable to save domain status with RTC change");
+ if (vm->def->clock.data.variable.basis == VIR_DOMAIN_CLOCK_BASIS_LOCALTIME) {
+ /* in the case of basis='localtime', the adjustment stored
+ * in the domain status contains the adjustment to move
+ * the RTC to localtime, *not* UTC. But the offset sent in
+ * the RTCChange event is defined to always send the new
+ * offset from UTC, regardless of libvirt domain clock
+ * configuration. So we must add the additional offset
+ * between localtime and UTC to the offset sent in the
+ * event.
+ */
+ offset += vm->def->clock.data.variable.localtimeAdjustment0;
+ }
+
+ if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)
+ VIR_WARN("unable to save domain status with RTC change");
+ }
+
+ event = virDomainEventRTCChangeNewFromObj(vm, offset);
virObjectUnlock(vm);
--
1.9.0
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