Re: [PATCH v1 5/9] hw/virtio: introduce virtio_device_should_start

[Alex Bennée]

Christian Borntraeger <borntraeger@linux.ibm.com> writes:

> Am 15.11.22 um 15:31 schrieb Alex Bennée:
>> "Michael S. Tsirkin" <mst@redhat.com> writes:
>> 
>>> On Mon, Nov 14, 2022 at 06:15:30PM +0100, Christian Borntraeger wrote:
>>>>
>>>>
>>>> Am 14.11.22 um 18:10 schrieb Michael S. Tsirkin:
>>>>> On Mon, Nov 14, 2022 at 05:55:09PM +0100, Christian Borntraeger wrote:
>>>>>>
>>>>>>
>>>>>> Am 14.11.22 um 17:37 schrieb Michael S. Tsirkin:
>>>>>>> On Mon, Nov 14, 2022 at 05:18:53PM +0100, Christian Borntraeger wrote:
>>>>>>>> Am 08.11.22 um 10:23 schrieb Alex Bennée:
>>>>>>>>> The previous fix to virtio_device_started revealed a problem in its
>>>>>>>>> use by both the core and the device code. The core code should be able
>>>>>>>>> to handle the device "starting" while the VM isn't running to handle
>>>>>>>>> the restoration of migration state. To solve this dual use introduce a
>>>>>>>>> new helper for use by the vhost-user backends who all use it to feed a
>>>>>>>>> should_start variable.
>>>>>>>>>
>>>>>>>>> We can also pick up a change vhost_user_blk_set_status while we are at
>>>>>>>>> it which follows the same pattern.
>>>>>>>>>
>>>>>>>>> Fixes: 9f6bcfd99f (hw/virtio: move vm_running check to 
>>>>>>>>> virtio_device_started)
>>>>>>>>> Fixes: 27ba7b027f (hw/virtio: add boilerplate for vhost-user-gpio 
>>>>>>>>> device)
>>>>>>>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>>>>>>>> Cc: "Michael S. Tsirkin" <mst@redhat.com>
>>>>>>>>
>>>>>>>> Hmmm, is this
>>>>>>>> commit 259d69c00b67c02a67f3bdbeeea71c2c0af76c35
>>>>>>>> Author:     Alex Bennée <alex.bennee@linaro.org>
>>>>>>>> AuthorDate: Mon Nov 7 12:14:07 2022 +0000
>>>>>>>> Commit:     Michael S. Tsirkin <mst@redhat.com>
>>>>>>>> CommitDate: Mon Nov 7 14:08:18 2022 -0500
>>>>>>>>
>>>>>>>>        hw/virtio: introduce virtio_device_should_start
>>>>>>>>
>>>>>>>> and older version?
>>>>>>>
>>>>>>> This is what got merged:
>>>>>>> https://lore.kernel.org/r/20221107121407.1010913-1-alex.bennee%40linaro.org
>>>>>>> This patch was sent after I merged the RFC.
>>>>>>> I think the only difference is the commit log but I might be missing
>>>>>>> something.
>>>>>>>
>>>>>>>> This does not seem to fix the regression that I have reported.
>>>>>>>
>>>>>>> This was applied on top of 9f6bcfd99f which IIUC does, right?
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> QEMU master still fails for me for suspend/resume to disk:
>>>>>>
>>>>>> #0  0x000003ff8e3980a6 in __pthread_kill_implementation () at 
>>>>>> /lib64/libc.so.6
>>>>>> #1  0x000003ff8e348580 in raise () at /lib64/libc.so.6
>>>>>> #2  0x000003ff8e32b5c0 in abort () at /lib64/libc.so.6
>>>>>> #3  0x000003ff8e3409da in __assert_fail_base () at /lib64/libc.so.6
>>>>>> #4  0x000003ff8e340a4e in  () at /lib64/libc.so.6
>>>>>> #5 0x000002aa1ffa8966 in vhost_vsock_common_pre_save
>>>>>> (opaque=<optimized out>) at
>>>>>> ../hw/virtio/vhost-vsock-common.c:203
>>>>>> #6  0x000002aa1fe5e0ee in vmstate_save_state_v
>>>>>>       (f=f@entry=0x2aa21bdc170, vmsd=0x2aa204ac5f0
>>>>>> <vmstate_virtio_vhost_vsock>, opaque=0x2aa21bac9f8,
>>>>>> vmdesc=vmdesc@entry=0x3fddc08eb30,
>>>>>> version_id=version_id@entry=0) at ../migration/vmstate.c:329
>>>>>> #7 0x000002aa1fe5ebf8 in vmstate_save_state
>>>>>> (f=f@entry=0x2aa21bdc170, vmsd=<optimized out>,
>>>>>> opaque=<optimized out>, vmdesc_id=vmdesc_id@entry=0x3fddc08eb30)
>>>>>> at ../migration/vmstate.c:317
>>>>>> #8 0x000002aa1fe75bd0 in vmstate_save (f=f@entry=0x2aa21bdc170,
>>>>>> se=se@entry=0x2aa21bdbe90, vmdesc=vmdesc@entry=0x3fddc08eb30) at
>>>>>> ../migration/savevm.c:908
>>>>>> #9 0x000002aa1fe79584 in
>>>>>> qemu_savevm_state_complete_precopy_non_iterable
>>>>>> (f=f@entry=0x2aa21bdc170, in_postcopy=in_postcopy@entry=false,
>>>>>> inactivate_disks=inactivate_disks@entry=true)
>>>>>>       at ../migration/savevm.c:1393
>>>>>> #10 0x000002aa1fe79a96 in qemu_savevm_state_complete_precopy
>>>>>> (f=0x2aa21bdc170, iterable_only=iterable_only@entry=false,
>>>>>> inactivate_disks=inactivate_disks@entry=true) at
>>>>>> ../migration/savevm.c:1459
>>>>>> #11 0x000002aa1fe6d6ee in migration_completion (s=0x2aa218ef600) at 
>>>>>> ../migration/migration.c:3314
>>>>>> #12 migration_iteration_run (s=0x2aa218ef600) at 
>>>>>> ../migration/migration.c:3761
>>>>>> #13 migration_thread (opaque=opaque@entry=0x2aa218ef600) at 
>>>>>> ../migration/migration.c:3989
>>>>>> #14 0x000002aa201f0b8c in qemu_thread_start (args=<optimized out>) at 
>>>>>> ../util/qemu-thread-posix.c:505
>>>>>> #15 0x000003ff8e396248 in start_thread () at /lib64/libc.so.6
>>>>>> #16 0x000003ff8e41183e in thread_start () at /lib64/libc.so.6
>>>>>>
>>>>>> Michael, your previous branch did work if I recall correctly.
>>>>>
>>>>> That one was failing under github CI though (for reasons we didn't
>>>>> really address, such as disconnect during stop causing a recursive
>>>>> call to stop, but there you are).
>>>> Even the double revert of everything?
>>>
>>> I don't remember at this point.
>>>
>>>> So how do we proceed now?
>>>
>>> I'm hopeful Alex will come up with a fix.
>> I need to replicate the failing test for that. Which test is
>> failing?
>
>
> Pretty much the same as before. guest with vsock, managedsave and
> restore.

If this isn't in our test suite I'm going to need exact steps.

-- 
Alex Bennée