On 10.01.23 21:03, Peter Xu wrote:
On Tue, Jan 10, 2023 at 12:52:32PM +0100, David Hildenbrand wrote:
The following seems to work,
That looks much better at least from the diffstat pov (comparing to the
existing patch 1+5 and the framework changes), thanks.
but makes analyze-migration.py angry:
$ ./scripts/analyze-migration.py -f STATEFILE
Traceback (most recent call last):
File "/home/dhildenb/git/qemu/./scripts/analyze-migration.py", line 605, in
<module>
dump.read(dump_memory = args.memory)
File "/home/dhildenb/git/qemu/./scripts/analyze-migration.py", line 539, in
read
classdesc = self.section_classes[section_key]
~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
KeyError: ('0000:00:03.0/virtio-mem-early', 0)
We need the vmdesc to create info for the device.
Migration may ignore the save entry if save_state() not provided in the
"devices" section:
if ((!se->ops || !se->ops->save_state) && !se->vmsd) {
continue;
}
Could you try providing a shim save_state() for the new virtio-mem save
entry?
/*
* Shim function to make sure the save entry will be dumped into "devices"
* section, to make analyze-migration.py happy.
*/
static void virtio_mem_save_state_early(QEMUFile *file, void *opaque)
{
}
Then:
static const SaveVMHandlers vmstate_virtio_mem_device_early_ops = {
.save_setup = virtio_mem_save_setup_early,
.save_state = virtio_mem_save_state_early,
.load_state = virtio_mem_load_state_early,
};
I'm not 100% sure it'll work yet, but maybe worth trying.
It doesn't. virtio_mem_load_state_early() will get called twice (once
with state saved during save_setup() and once with effectively nothing
during save_state(), which breaks the whole migration).
vmdesc handling is also wrong, because analyze-migration.py gets
confused because it receives data stored during save_setup() but vmdesc
created during save_state() was told that there would be "nothing" to
interpret ...
$ ./scripts/analyze-migration.py -f STATEFILE
{
"ram (2)": {
"section sizes": {
"0000:00:03.0/mem0": "0x0000000f00000000",
"pc.ram": "0x0000000100000000",
"/rom@etc/acpi/tables": "0x0000000000020000",
"pc.bios": "0x0000000000040000",
"0000:00:02.0/e1000.rom": "0x0000000000040000",
"pc.rom": "0x0000000000020000",
"/rom@etc/table-loader": "0x0000000000001000",
"/rom@etc/acpi/rsdp": "0x0000000000001000"
}
},
"0000:00:03.0/virtio-mem-early (51)": {
"data": ""
}
}
Not sure if the whole thing becomes nicer when manually looking up the
vmdesc ... because filling it will also requires manually storing the
se->idstr and the se->instance_id, whereby both are migration-internal
and not available inside save_setup().
Hm, I really prefer something like the simplified version that let's
migration core deal with vmstate to be migrated during save_setup()
phase. We could avoid the vmstate->immutable flag and simply use a
separate function for registering the vmstate, like:
vmstate_register_immutable()
vmstate_register_early()
...
--
Thanks,
David / dhildenb
