Re: [RFC PATCH] virtio: re-order vm_running and use_started checks

["Alex Bennée" <alex.bennee@linaro.org>]

"Michael S. Tsirkin" <mst@redhat.com> writes:

> On Fri, Oct 14, 2022 at 02:21:08PM +0100, Alex Bennée wrote:
>> During migration the virtio device state can be restored before we
>> restart the VM. As no devices can be running while the VM is paused it
>> makes sense to bail out early in that case.
>> 
>> This returns the order introduced in:
>> 
>>  9f6bcfd99f (hw/virtio: move vm_running check to virtio_device_started)
>> 
>> to what virtio-sock was doing longhand.
>> 
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
>
>
> What happens now:
>
> with this applied I get:
>
> https://gitlab.com/mitsirkin/qemu/-/pipelines/685829158/failures
>
> ――――――――――――――――――――――――――――――――――――― ✀  ―――――――――――――――――――――――――――――――――――――
> stderr:
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 20.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: -chardev
> socket,id=chr-reconnect,path=/tmp/vhost-test-QLKXU1/reconnect.sock,server=on:
> info: QEMU waiting for connection on:
> disconnected:unix:/tmp/vhost-test-QLKXU1/reconnect.sock,server=on
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 20.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: -chardev
> socket,id=chr-connect-fail,path=/tmp/vhost-test-L9Q6U1/connect-fail.sock,server=on:
> info: QEMU waiting for connection on:
> disconnected:unix:/tmp/vhost-test-L9Q6U1/connect-fail.sock,server=on
> qemu-system-arm: -netdev
> vhost-user,id=hs0,chardev=chr-connect-fail,vhostforce=on: Failed to
> read msg header. Read 0 instead of 12. Original request 1.
> qemu-system-arm: -netdev
> vhost-user,id=hs0,chardev=chr-connect-fail,vhostforce=on:
> vhost_backend_init failed: Protocol error
> qemu-system-arm: -netdev
> vhost-user,id=hs0,chardev=chr-connect-fail,vhostforce=on: failed to
> init vhost_net for queue 0
> qemu-system-arm: -netdev
> vhost-user,id=hs0,chardev=chr-connect-fail,vhostforce=on: info: QEMU
> waiting for connection on:
> disconnected:unix:/tmp/vhost-test-L9Q6U1/connect-fail.sock,server=on
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 20.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: -chardev
> socket,id=chr-flags-mismatch,path=/tmp/vhost-test-3MO5U1/flags-mismatch.sock,server=on:
> info: QEMU waiting for connection on:
> disconnected:unix:/tmp/vhost-test-3MO5U1/flags-mismatch.sock,server=on
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 52.
> qemu-system-arm: vhost_set_mem_table failed: Invalid argument (22)
> qemu-system-arm: unable to start vhost net: 22: falling back on userspace virtio
> vhost lacks feature mask 0x40000000 for backend
> qemu-system-arm: failed to init vhost_net for queue 0
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 20.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 2 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 3 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 20.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 20.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 0 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost VQ 1 ring restore failed: -22: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost_set_vring_call failed: Invalid argument (22)
> qemu-system-arm: Failed to set msg fds.
> qemu-system-arm: vhost_set_vring_call failed: Invalid argument (22)
> qemu-system-arm: Failed to write msg. Wrote -1 instead of 20.
> qemu-system-arm: vhost VQ 0 ring restore failed: -5: Input/output error (5)
> qemu-system-arm: ../hw/virtio/virtio-bus.c:211: void
> virtio_bus_release_ioeventfd(VirtioBusState *): Assertion
> `bus->ioeventfd_grabbed != 0' failed.
> ../tests/qtest/libqtest.c:188: kill_qemu() detected QEMU death from signal 6 (Aborted) (core dumped)
> **
> ERROR:../tests/qtest/qos-test.c:191:subprocess_run_one_test: child
> process
> (/arm/virt/virtio-mmio/virtio-bus/vhost-user-gpio-device/vhost-user-gpio/vhost-user-gpio-tests/read-guest-mem/memfile/subprocess
> [8735]) failed unexpectedly
> (test program exited with status code -6)
> ――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
>
>
>
>
> without this it passes:
>
> https://gitlab.com/mitsirkin/qemu/-/jobs/3275949777
>
>
> this only triggers under github, clang-system job.
> trying to decide what to do now. revert just this?

I must admit I didn't run that directly. My build box is currently out
of commission but can we get more detail about the abort?

It looks like the vhost negotiation is totally broken and can't even
find the VQs

>
>
>> ---
>>  include/hw/virtio/virtio.h | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>> 
>> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
>> index f41b4a7e64..ebb58feaac 100644
>> --- a/include/hw/virtio/virtio.h
>> +++ b/include/hw/virtio/virtio.h
>> @@ -385,14 +385,14 @@ static inline bool virtio_is_big_endian(VirtIODevice *vdev)
>>  
>>  static inline bool virtio_device_started(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;
>>  }
>>  
>> -- 
>> 2.34.1


-- 
Alex Bennée