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			Commit 02b61f38d3 ("hw/virtio: incorporate backend features in features")
properly negotiates VHOST_USER_F_PROTOCOL_FEATURES with the vhost-user
backend, but we forgot to enable vrings as specified in
docs/interop/vhost-user.rst:
    If ``VHOST_USER_F_PROTOCOL_FEATURES`` has not been negotiated, the
    ring starts directly in the enabled state.
    If ``VHOST_USER_F_PROTOCOL_FEATURES`` has been negotiated, the ring is
    initialized in a disabled state and is enabled by
    ``VHOST_USER_SET_VRING_ENABLE`` with parameter 1.
Some vhost-user front-ends already did this by calling
vhost_ops.vhost_set_vring_enable() directly:
- backends/cryptodev-vhost.c
- hw/net/virtio-net.c
- hw/virtio/vhost-user-gpio.c
But most didn't do that, so we would leave the vrings disabled and some
backends would not work. We observed this issue with the rust version of
virtiofsd [1], which uses the event loop [2] provided by the
vhost-user-backend crate where requests are not processed if vring is
not enabled.
Let's fix this issue by enabling the vrings in vhost_dev_start() for
vhost-user front-ends that don't already do this directly. Same thing
also in vhost_dev_stop() where we disable vrings.
[1] https://gitlab.com/virtio-fs/virtiofsd
[2] https://github.com/rust-vmm/vhost/blob/240fc2966/crates/vhost-user-backend/src/event_loop.rs#L217
Fixes: 02b61f38d3 ("hw/virtio: incorporate backend features in features")
Reported-by: German Maglione <gmaglione@redhat.com>
Tested-by: German Maglione <gmaglione@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20221123131630.52020-1-sgarzare@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20221130112439.2527228-3-alex.bennee@linaro.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
		
	
			
		
			
				
	
	
		
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			172 lines
		
	
	
		
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| /*
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|  * vhost-scsi-common
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|  *
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|  * Copyright (c) 2016 Nutanix Inc. All rights reserved.
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|  *
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|  * Author:
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|  *  Felipe Franciosi <felipe@nutanix.com>
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|  *
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|  * This work is largely based on the "vhost-scsi" implementation by:
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|  *  Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
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|  *  Nicholas Bellinger <nab@risingtidesystems.com>
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|  *
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|  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
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|  * See the COPYING.LIB file in the top-level directory.
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|  *
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|  */
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| 
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| #include "qemu/osdep.h"
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| #include "qemu/error-report.h"
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| #include "qemu/module.h"
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| #include "hw/virtio/vhost.h"
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| #include "hw/virtio/vhost-scsi-common.h"
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| #include "hw/virtio/virtio-scsi.h"
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| #include "hw/virtio/virtio-bus.h"
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| #include "hw/virtio/virtio-access.h"
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| #include "hw/fw-path-provider.h"
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| 
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| int vhost_scsi_common_start(VHostSCSICommon *vsc)
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| {
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|     int ret, i;
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|     VirtIODevice *vdev = VIRTIO_DEVICE(vsc);
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|     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
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|     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
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| 
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|     VirtIOSCSICommon *vs = (VirtIOSCSICommon *)vsc;
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| 
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|     if (!k->set_guest_notifiers) {
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|         error_report("binding does not support guest notifiers");
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|         return -ENOSYS;
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|     }
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| 
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|     ret = vhost_dev_enable_notifiers(&vsc->dev, vdev);
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|     if (ret < 0) {
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|         return ret;
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|     }
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| 
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|     ret = k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, true);
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|     if (ret < 0) {
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|         error_report("Error binding guest notifier");
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|         goto err_host_notifiers;
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|     }
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| 
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|     vsc->dev.acked_features = vdev->guest_features;
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| 
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|     assert(vsc->inflight == NULL);
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|     vsc->inflight = g_new0(struct vhost_inflight, 1);
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|     ret = vhost_dev_get_inflight(&vsc->dev,
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|                                  vs->conf.virtqueue_size,
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|                                  vsc->inflight);
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|     if (ret < 0) {
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|         error_report("Error get inflight: %d", -ret);
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|         goto err_guest_notifiers;
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|     }
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| 
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|     ret = vhost_dev_set_inflight(&vsc->dev, vsc->inflight);
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|     if (ret < 0) {
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|         error_report("Error set inflight: %d", -ret);
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|         goto err_guest_notifiers;
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|     }
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| 
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|     ret = vhost_dev_start(&vsc->dev, vdev, true);
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|     if (ret < 0) {
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|         error_report("Error start vhost dev");
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|         goto err_guest_notifiers;
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|     }
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| 
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|     /* guest_notifier_mask/pending not used yet, so just unmask
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|      * everything here.  virtio-pci will do the right thing by
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|      * enabling/disabling irqfd.
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|      */
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|     for (i = 0; i < vsc->dev.nvqs; i++) {
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|         vhost_virtqueue_mask(&vsc->dev, vdev, vsc->dev.vq_index + i, false);
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|     }
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| 
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|     return ret;
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| 
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| err_guest_notifiers:
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|     g_free(vsc->inflight);
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|     vsc->inflight = NULL;
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| 
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|     k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, false);
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| err_host_notifiers:
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|     vhost_dev_disable_notifiers(&vsc->dev, vdev);
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|     return ret;
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| }
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| 
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| void vhost_scsi_common_stop(VHostSCSICommon *vsc)
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| {
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|     VirtIODevice *vdev = VIRTIO_DEVICE(vsc);
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|     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
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|     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
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|     int ret = 0;
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| 
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|     vhost_dev_stop(&vsc->dev, vdev, true);
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| 
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|     if (k->set_guest_notifiers) {
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|         ret = k->set_guest_notifiers(qbus->parent, vsc->dev.nvqs, false);
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|         if (ret < 0) {
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|                 error_report("vhost guest notifier cleanup failed: %d", ret);
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|         }
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|     }
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|     assert(ret >= 0);
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| 
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|     if (vsc->inflight) {
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|         vhost_dev_free_inflight(vsc->inflight);
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|         vsc->inflight = NULL;
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|     }
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| 
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|     vhost_dev_disable_notifiers(&vsc->dev, vdev);
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| }
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| 
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| uint64_t vhost_scsi_common_get_features(VirtIODevice *vdev, uint64_t features,
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|                                         Error **errp)
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| {
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|     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(vdev);
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| 
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|     /* Turn on predefined features supported by this device */
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|     features |= vsc->host_features;
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| 
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|     return vhost_get_features(&vsc->dev, vsc->feature_bits, features);
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| }
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| 
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| void vhost_scsi_common_set_config(VirtIODevice *vdev, const uint8_t *config)
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| {
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|     VirtIOSCSIConfig *scsiconf = (VirtIOSCSIConfig *)config;
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|     VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
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| 
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|     if ((uint32_t)virtio_ldl_p(vdev, &scsiconf->sense_size) != vs->sense_size ||
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|         (uint32_t)virtio_ldl_p(vdev, &scsiconf->cdb_size) != vs->cdb_size) {
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|         error_report("vhost-scsi does not support changing the sense data and "
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|                      "CDB sizes");
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|         exit(1);
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|     }
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| }
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| 
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| /*
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|  * Implementation of an interface to adjust firmware path
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|  * for the bootindex property handling.
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|  */
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| char *vhost_scsi_common_get_fw_dev_path(FWPathProvider *p, BusState *bus,
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|                                         DeviceState *dev)
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| {
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|     VHostSCSICommon *vsc = VHOST_SCSI_COMMON(dev);
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|     /* format: /channel@channel/vhost-scsi@target,lun */
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|     return g_strdup_printf("/channel@%x/%s@%x,%x", vsc->channel,
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|                            qdev_fw_name(dev), vsc->target, vsc->lun);
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| }
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| 
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| static const TypeInfo vhost_scsi_common_info = {
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|     .name = TYPE_VHOST_SCSI_COMMON,
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|     .parent = TYPE_VIRTIO_SCSI_COMMON,
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|     .instance_size = sizeof(VHostSCSICommon),
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|     .abstract = true,
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| };
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| 
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| static void virtio_register_types(void)
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| {
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|     type_register_static(&vhost_scsi_common_info);
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| }
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| 
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| type_init(virtio_register_types)
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