qemu-e2k/hw/scsi/vhost-user-scsi.c

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/*
* vhost-user-scsi host device
*
* Copyright (c) 2016 Nutanix Inc. All rights reserved.
*
* Author:
* Felipe Franciosi <felipe@nutanix.com>
*
* This work is largely based on the "vhost-scsi" implementation by:
* Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
* Nicholas Bellinger <nab@risingtidesystems.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "hw/fw-path-provider.h"
#include "hw/qdev-core.h"
#include "hw/qdev-properties.h"
#include "hw/qdev-properties-system.h"
#include "hw/virtio/vhost.h"
#include "hw/virtio/vhost-backend.h"
#include "hw/virtio/vhost-user-scsi.h"
#include "hw/virtio/virtio.h"
#include "hw/virtio/virtio-access.h"
#include "chardev/char-fe.h"
#include "sysemu/sysemu.h"
/* Features supported by the host application */
static const int user_feature_bits[] = {
VIRTIO_F_NOTIFY_ON_EMPTY,
VIRTIO_RING_F_INDIRECT_DESC,
VIRTIO_RING_F_EVENT_IDX,
VIRTIO_SCSI_F_HOTPLUG,
VHOST_INVALID_FEATURE_BIT
};
enum VhostUserProtocolFeature {
VHOST_USER_PROTOCOL_F_RESET_DEVICE = 13,
};
static void vhost_user_scsi_set_status(VirtIODevice *vdev, uint8_t status)
{
VHostUserSCSI *s = (VHostUserSCSI *)vdev;
VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
bool start = (status & VIRTIO_CONFIG_S_DRIVER_OK) && vdev->vm_running;
if (vsc->dev.started == start) {
return;
}
if (start) {
int ret;
ret = vhost_scsi_common_start(vsc);
if (ret < 0) {
error_report("unable to start vhost-user-scsi: %s", strerror(-ret));
exit(1);
}
} else {
vhost_scsi_common_stop(vsc);
}
}
static void vhost_user_scsi_reset(VirtIODevice *vdev)
{
VHostSCSICommon *vsc = VHOST_SCSI_COMMON(vdev);
struct vhost_dev *dev = &vsc->dev;
/*
* Historically, reset was not implemented so only reset devices
* that are expecting it.
*/
if (!virtio_has_feature(dev->protocol_features,
VHOST_USER_PROTOCOL_F_RESET_DEVICE)) {
return;
}
if (dev->vhost_ops->vhost_reset_device) {
dev->vhost_ops->vhost_reset_device(dev);
}
}
static void vhost_dummy_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
}
static void vhost_user_scsi_realize(DeviceState *dev, Error **errp)
{
VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
VHostUserSCSI *s = VHOST_USER_SCSI(dev);
VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
struct vhost_virtqueue *vqs = NULL;
Error *err = NULL;
int ret;
if (!vs->conf.chardev.chr) {
error_setg(errp, "vhost-user-scsi: missing chardev");
return;
}
virtio_scsi_common_realize(dev, vhost_dummy_handle_output,
vhost_dummy_handle_output,
vhost_dummy_handle_output, &err);
if (err != NULL) {
error_propagate(errp, err);
return;
}
if (!vhost_user_init(&s->vhost_user, &vs->conf.chardev, errp)) {
goto free_virtio;
}
vsc->dev.nvqs = VIRTIO_SCSI_VQ_NUM_FIXED + vs->conf.num_queues;
vsc->dev.vqs = g_new0(struct vhost_virtqueue, vsc->dev.nvqs);
vsc->dev.vq_index = 0;
vsc->dev.backend_features = 0;
vqs = vsc->dev.vqs;
s->vhost_user.supports_config = true;
ret = vhost_dev_init(&vsc->dev, &s->vhost_user,
VHOST_BACKEND_TYPE_USER, 0, errp);
if (ret < 0) {
goto free_vhost;
}
/* Channel and lun both are 0 for bootable vhost-user-scsi disk */
vsc->channel = 0;
vsc->lun = 0;
vsc->target = vs->conf.boot_tpgt;
return;
free_vhost:
vhost_user_cleanup(&s->vhost_user);
g_free(vqs);
free_virtio:
virtio_scsi_common_unrealize(dev);
}
qdev: Unrealize must not fail Devices may have component devices and buses. Device realization may fail. Realization is recursive: a device's realize() method realizes its components, and device_set_realized() realizes its buses (which should in turn realize the devices on that bus, except bus_set_realized() doesn't implement that, yet). When realization of a component or bus fails, we need to roll back: unrealize everything we realized so far. If any of these unrealizes failed, the device would be left in an inconsistent state. Must not happen. device_set_realized() lets it happen: it ignores errors in the roll back code starting at label child_realize_fail. Since realization is recursive, unrealization must be recursive, too. But how could a partly failed unrealize be rolled back? We'd have to re-realize, which can fail. This design is fundamentally broken. device_set_realized() does not roll back at all. Instead, it keeps unrealizing, ignoring further errors. It can screw up even for a device with no buses: if the lone dc->unrealize() fails, it still unregisters vmstate, and calls listeners' unrealize() callback. bus_set_realized() does not roll back either. Instead, it stops unrealizing. Fortunately, no unrealize method can fail, as we'll see below. To fix the design error, drop parameter @errp from all the unrealize methods. Any unrealize method that uses @errp now needs an update. This leads us to unrealize() methods that can fail. Merely passing it to another unrealize method cannot cause failure, though. Here are the ones that do other things with @errp: * virtio_serial_device_unrealize() Fails when qbus_set_hotplug_handler() fails, but still does all the other work. On failure, the device would stay realized with its resources completely gone. Oops. Can't happen, because qbus_set_hotplug_handler() can't actually fail here. Pass &error_abort to qbus_set_hotplug_handler() instead. * hw/ppc/spapr_drc.c's unrealize() Fails when object_property_del() fails, but all the other work is already done. On failure, the device would stay realized with its vmstate registration gone. Oops. Can't happen, because object_property_del() can't actually fail here. Pass &error_abort to object_property_del() instead. * spapr_phb_unrealize() Fails and bails out when remove_drcs() fails, but other work is already done. On failure, the device would stay realized with some of its resources gone. Oops. remove_drcs() fails only when chassis_from_bus()'s object_property_get_uint() fails, and it can't here. Pass &error_abort to remove_drcs() instead. Therefore, no unrealize method can fail before this patch. device_set_realized()'s recursive unrealization via bus uses object_property_set_bool(). Can't drop @errp there, so pass &error_abort. We similarly unrealize with object_property_set_bool() elsewhere, always ignoring errors. Pass &error_abort instead. Several unrealize methods no longer handle errors from other unrealize methods: virtio_9p_device_unrealize(), virtio_input_device_unrealize(), scsi_qdev_unrealize(), ... Much of the deleted error handling looks wrong anyway. One unrealize methods no longer ignore such errors: usb_ehci_pci_exit(). Several realize methods no longer ignore errors when rolling back: v9fs_device_realize_common(), pci_qdev_unrealize(), spapr_phb_realize(), usb_qdev_realize(), vfio_ccw_realize(), virtio_device_realize(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200505152926.18877-17-armbru@redhat.com>
2020-05-05 17:29:24 +02:00
static void vhost_user_scsi_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserSCSI *s = VHOST_USER_SCSI(dev);
VHostSCSICommon *vsc = VHOST_SCSI_COMMON(s);
struct vhost_virtqueue *vqs = vsc->dev.vqs;
/* This will stop the vhost backend. */
vhost_user_scsi_set_status(vdev, 0);
vhost_dev_cleanup(&vsc->dev);
g_free(vqs);
virtio_scsi_common_unrealize(dev);
vhost_user_cleanup(&s->vhost_user);
}
static Property vhost_user_scsi_properties[] = {
DEFINE_PROP_CHR("chardev", VirtIOSCSICommon, conf.chardev),
DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0),
DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues,
VIRTIO_SCSI_AUTO_NUM_QUEUES),
DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSICommon, conf.virtqueue_size,
128),
DEFINE_PROP_UINT32("max_sectors", VirtIOSCSICommon, conf.max_sectors,
0xFFFF),
DEFINE_PROP_UINT32("cmd_per_lun", VirtIOSCSICommon, conf.cmd_per_lun, 128),
DEFINE_PROP_BIT64("hotplug", VHostSCSICommon, host_features,
VIRTIO_SCSI_F_HOTPLUG,
true),
DEFINE_PROP_BIT64("param_change", VHostSCSICommon, host_features,
VIRTIO_SCSI_F_CHANGE,
true),
DEFINE_PROP_BIT64("t10_pi", VHostSCSICommon, host_features,
VIRTIO_SCSI_F_T10_PI,
false),
DEFINE_PROP_END_OF_LIST(),
};
static const VMStateDescription vmstate_vhost_scsi = {
.name = "virtio-scsi",
.minimum_version_id = 1,
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_VIRTIO_DEVICE,
VMSTATE_END_OF_LIST()
},
};
static void vhost_user_scsi_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
FWPathProviderClass *fwc = FW_PATH_PROVIDER_CLASS(klass);
device_class_set_props(dc, vhost_user_scsi_properties);
dc->vmsd = &vmstate_vhost_scsi;
set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
vdc->realize = vhost_user_scsi_realize;
vdc->unrealize = vhost_user_scsi_unrealize;
vdc->get_features = vhost_scsi_common_get_features;
vdc->set_config = vhost_scsi_common_set_config;
vdc->set_status = vhost_user_scsi_set_status;
vdc->reset = vhost_user_scsi_reset;
fwc->get_dev_path = vhost_scsi_common_get_fw_dev_path;
}
static void vhost_user_scsi_instance_init(Object *obj)
{
VHostSCSICommon *vsc = VHOST_SCSI_COMMON(obj);
vsc->feature_bits = user_feature_bits;
/* Add the bootindex property for this object */
device_add_bootindex_property(obj, &vsc->bootindex, "bootindex", NULL,
DEVICE(vsc));
}
static const TypeInfo vhost_user_scsi_info = {
.name = TYPE_VHOST_USER_SCSI,
.parent = TYPE_VHOST_SCSI_COMMON,
.instance_size = sizeof(VHostUserSCSI),
.class_init = vhost_user_scsi_class_init,
.instance_init = vhost_user_scsi_instance_init,
.interfaces = (InterfaceInfo[]) {
{ TYPE_FW_PATH_PROVIDER },
{ }
},
};
static void virtio_register_types(void)
{
type_register_static(&vhost_user_scsi_info);
}
type_init(virtio_register_types)