Migration just seems to go from bad to worse. We already had to
introduce a second migration protocol when adding the QEMU driver,
since the one from Xen was insufficiently flexible to cope with
passing the data the QEMU driver required.
It turns out that this protocol still has some flaws that we
need to address. The current sequence is
* Src: DumpXML
- Generate XML to pass to dst
* Dst: Prepare
- Get ready to accept incoming VM
- Generate optional cookie to pass to src
* Src: Perform
- Start migration and wait for send completion
- Kill off VM if successful, resume if failed
* Dst: Finish
- Wait for recv completion and check status
- Kill off VM if unsuccessful
The problems with this are:
- Since the first step is a generic 'DumpXML' call, we can't
add in other migration specific data. eg, we can't include
any VM lease data from lock manager plugins
- Since the first step is a generic 'DumpXML' call, we can't
emit any 'migration begin' event on the source, or have
any hook that runs right at the start of the process
- Since there is no final step on the source, if the Finish
method fails to receive all migration data & has to kill
the VM, then there's no way to resume the original VM
on the source
This patch attempts to introduce a version 3 that uses the
improved 5 step sequence
* Src: Begin
- Generate XML to pass to dst
- Generate optional cookie to pass to dst
* Dst: Prepare
- Get ready to accept incoming VM
- Generate optional cookie to pass to src
* Src: Perform
- Start migration and wait for send completion
- Generate optional cookie to pass to dst
* Dst: Finish
- Wait for recv completion and check status
- Kill off VM if failed, resume if success
- Generate optional cookie to pass to src
* Src: Confirm
- Kill off VM if success, resume if failed
The API is designed to allow both input and output cookies
in all methods where applicable. This lets us pass around
arbitrary extra driver specific data between src & dst during
migration. Combined with the extra 'Begin' method this lets
us pass lease information from source to dst at the start of
migration
Moving the killing of the source VM out of Perform and
into Confirm, means we can now recover if the dst host
can't successfully Finish receiving migration data.
The hvsupport.html.in file is forever out of date. By annotating
the driver struct tables in each driver with version information,
we can auto-generate the hvsupport.html.in file. Annotating the
drivers will be mandatory for new patches, ensuring hvsupport.html.in
is never out of date again.
* docs/hvsupport.html.in: Delete
* hvsupport.pl: Script to generate hvsupport.html.in
* Makefile.am: Autogenerate hvsupport.html.in
Change all the driver struct initializers to use the
C99 style, leaving out unused fields. This will make
it possible to add new APIs without changing every
driver. eg change:
qemudDomainResume, /* domainResume */
qemudDomainShutdown, /* domainShutdown */
NULL, /* domainReboot */
qemudDomainDestroy, /* domainDestroy */
to
.domainResume = qemudDomainResume,
.domainShutdown = qemudDomainShutdown,
.domainDestroy = qemudDomainDestroy,
And get rid of any existing C99 style initializersr which
set NULL, eg change
.listPools = vboxStorageListPools,
.numOfDefinedPools = NULL,
.listDefinedPools = NULL,
.findPoolSources = NULL,
.poolLookupByName = vboxStoragePoolLookupByName,
to
.listPools = vboxStorageListPools,
.poolLookupByName = vboxStoragePoolLookupByName,
Fix some driver names:
s/virDrvCPUCompare/virDrvCompareCPU/
s/virDrvCPUBaseline/virDrvBaselineCPU/
s/virDrvQemuDomainMonitorCommand/virDrvDomainQemuMonitorCommand/
s/virDrvSecretNumOfSecrets/virDrvNumOfSecrets/
s/virDrvSecretListSecrets/virDrvListSecrets/
And some driver struct field names:
s/getFreeMemory/nodeGetFreeMemory/
Only in drivers which use virDomainObj, drivers that query hypervisor
for domain status need to be updated separately in case their hypervisor
supports this functionality.
The reason is also saved into domain state XML so if a domain is not
running (i.e., no state XML exists) the reason will be lost by libvirtd
restart. I think this is an acceptable limitation.
This has been present since the introduction of phypAttachDevice
in commit 444fd07a.
* src/phyp/phyp_driver.c (phypAttachDevice): Don't dereference
NULL.
virFDStreamClose used a mutex after it was freed, and failed
to destroy that mutex on its last use.
* src/fdstream.c (virFDStreamFree): Inline into sole caller...
(virFDStreamClose): ...to avoid use-after-free and leak.
Reported by Matthias Bolte.
Several vSphere API methods are called on global objects like the
FileManager, the PerformanceManager or the SearchIndex. The generator
input file allows to mark such methods and the generator generates
such method in a way that automatically handles marked parameter. This
is done by some special macros. Those were manually written and this
patch moves them to the generator.
One functionality change here is that we no longer force enable the event
timeout for every queued event, only enable it for the first event after
the queue has been flushed. This is how other drivers have already done it,
and I haven't encountered problems in practice.
v3:
Adjust for new virDomainEventStateNew argument
The same code for queueing, flushing, and deregistering events exists
in multiple drivers, which will soon use these common functions.
v2:
Adjust libvirt_private.syms
isDispatching bool fixes
NONNULL tagging
v3:
Add requireTimer parameter to virDomainEventStateNew
This structure will be used to unify lots of duplicated event handling code
across the state drivers.
v2:
Check for state == NULL in StateFree
Add NONNULL tagging
Use bool for isDispatching
Signed-off-by: Cole Robinson <crobinso@redhat.com>
Use capabilities to allow a driver to register a default <init> if none
is specified in the XML. Openvz was already open-coding this to be /sbin/init
LXC currently falls over if no init is specified, so an explicit error is
an improvement IMO.
(Side note: I don't think we can set a default value for LXC. If we use
/sbin/init but the user doesn't specify a separate root FS for their guest,
the container will rerun the host's init which can be traumatic :). For
virt-install I'm thinking of defaulting to /sbin/init if a root FS has
been specified, otherwise require the user to manually specify <init>)
This is needed if we want to transfer a temporary file. If the
transfer is done with iohelper, we might run into a race condition,
where we unlink() file before iohelper is executed.
* src/fdstream.c, src/fdstream.h,
src/util/iohelper.c: Add new option
* src/lxc/lxc_driver.c, src/qemu/qemu_driver.c,
src/storage/storage_driver.c, src/uml/uml_driver.c,
src/xen/xen_driver.c: Expand existing function calls
