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

["Michael S. Tsirkin" <mst@redhat.com>]

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

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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)
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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?


> ---
>  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