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

[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?

-- 
Alex Bennée