[Virtio-fs] [PATCH v1 5/9] hw/virtio: introduce virtio_device_should_start

Tue Nov 15 13:25:34 UTC 2022

Am 15.11.22 um 12:25 schrieb Michael S. Tsirkin:
> On Tue, Nov 15, 2022 at 09:18:27AM +0100, Christian Borntraeger wrote:
>>
>> Am 14.11.22 um 18:20 schrieb Michael S. Tsirkin:
>>> 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 at linaro.org>
>>>>>>>>> Cc: "Michael S. Tsirkin" <mst at redhat.com>
>>>>>>>>
>>>>>>>> Hmmm, is this
>>>>>>>> commit 259d69c00b67c02a67f3bdbeeea71c2c0af76c35
>>>>>>>> Author:     Alex Bennée <alex.bennee at linaro.org>
>>>>>>>> AuthorDate: Mon Nov 7 12:14:07 2022 +0000
>>>>>>>> Commit:     Michael S. Tsirkin <mst at 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 at entry=0x2aa21bdc170, vmsd=0x2aa204ac5f0 <vmstate_virtio_vhost_vsock>, opaque=0x2aa21bac9f8, vmdesc=vmdesc at entry=0x3fddc08eb30, version_id=version_id at entry=0) at ../migration/vmstate.c:329
>>>>>> #7  0x000002aa1fe5ebf8 in vmstate_save_state (f=f at entry=0x2aa21bdc170, vmsd=<optimized out>, opaque=<optimized out>, vmdesc_id=vmdesc_id at entry=0x3fddc08eb30) at ../migration/vmstate.c:317
>>>>>> #8  0x000002aa1fe75bd0 in vmstate_save (f=f at entry=0x2aa21bdc170, se=se at entry=0x2aa21bdbe90, vmdesc=vmdesc at entry=0x3fddc08eb30) at ../migration/savevm.c:908
>>>>>> #9  0x000002aa1fe79584 in qemu_savevm_state_complete_precopy_non_iterable (f=f at entry=0x2aa21bdc170, in_postcopy=in_postcopy at entry=false, inactivate_disks=inactivate_disks at entry=true)
>>>>>>        at ../migration/savevm.c:1393
>>>>>> #10 0x000002aa1fe79a96 in qemu_savevm_state_complete_precopy (f=0x2aa21bdc170, iterable_only=iterable_only at entry=false, inactivate_disks=inactivate_disks at 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 at 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.
>>
>>
>> The initial fix changed to qemu/master does still work for me
>>
>> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
>> index a973811cbfc6..fb3072838119 100644
>> --- a/include/hw/virtio/virtio.h
>> +++ b/include/hw/virtio/virtio.h
>> @@ -411,14 +411,14 @@ static inline bool virtio_device_started(VirtIODevice *vdev, uint8_t status)
>>    */
>>   static inline bool virtio_device_should_start(VirtIODevice *vdev, uint8_t status)
>>   {
>> -    if (vdev->use_started) {
>> -        return vdev->started;
>> -    }
>> -
>>       if (!vdev->vm_running) {
>>           return false;
>>       }
>> +    if (vdev->use_started) {
>> +        return vdev->started;
>> +    }
>> +
>>       return status & VIRTIO_CONFIG_S_DRIVER_OK;
>>   }
> 
> Triggers failure on gitlab unfortunately:
> 
> https://gitlab.com/mstredhat/qemu/-/jobs/3323768122

So maybe we should go forward and revert the whole thing?
After all 9f6bcfd99f mostly looks like a cleanup patch and not something that was really necessary.