Adding upstream version 1:7.2+dfsg.upstream/1%7.2+dfsgupstream

Signed-off-by: Daniel Baumann <mail@daniel-baumann.ch>

1 files changed, 1181 insertions, 0 deletions

diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
new file mode 100644
index 00000000..6f6e2e32
--- /dev/null
+++ b/hw/scsi/virtio-scsi.c
@@ -0,0 +1,1181 @@
+/*
+ * Virtio SCSI HBA
+ *
+ * Copyright IBM, Corp. 2010
+ * Copyright Red Hat, Inc. 2011
+ *
+ * Authors:
+ *   Stefan Hajnoczi    <stefanha@linux.vnet.ibm.com>
+ *   Paolo Bonzini      <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "standard-headers/linux/virtio_ids.h"
+#include "hw/virtio/virtio-scsi.h"
+#include "migration/qemu-file-types.h"
+#include "qemu/error-report.h"
+#include "qemu/iov.h"
+#include "qemu/module.h"
+#include "sysemu/block-backend.h"
+#include "hw/qdev-properties.h"
+#include "hw/scsi/scsi.h"
+#include "scsi/constants.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/virtio-access.h"
+#include "trace.h"
+
+typedef struct VirtIOSCSIReq {
+    /*
+     * Note:
+     * - fields up to resp_iov are initialized by virtio_scsi_init_req;
+     * - fields starting at vring are zeroed by virtio_scsi_init_req.
+     */
+    VirtQueueElement elem;
+
+    VirtIOSCSI *dev;
+    VirtQueue *vq;
+    QEMUSGList qsgl;
+    QEMUIOVector resp_iov;
+
+    union {
+        /* Used for two-stage request submission */
+        QTAILQ_ENTRY(VirtIOSCSIReq) next;
+
+        /* Used for cancellation of request during TMFs */
+        int remaining;
+    };
+
+    SCSIRequest *sreq;
+    size_t resp_size;
+    enum SCSIXferMode mode;
+    union {
+        VirtIOSCSICmdResp     cmd;
+        VirtIOSCSICtrlTMFResp tmf;
+        VirtIOSCSICtrlANResp  an;
+        VirtIOSCSIEvent       event;
+    } resp;
+    union {
+        VirtIOSCSICmdReq      cmd;
+        VirtIOSCSICtrlTMFReq  tmf;
+        VirtIOSCSICtrlANReq   an;
+    } req;
+} VirtIOSCSIReq;
+
+static inline int virtio_scsi_get_lun(uint8_t *lun)
+{
+    return ((lun[2] << 8) | lun[3]) & 0x3FFF;
+}
+
+static inline SCSIDevice *virtio_scsi_device_get(VirtIOSCSI *s, uint8_t *lun)
+{
+    if (lun[0] != 1) {
+        return NULL;
+    }
+    if (lun[2] != 0 && !(lun[2] >= 0x40 && lun[2] < 0x80)) {
+        return NULL;
+    }
+    return scsi_device_get(&s->bus, 0, lun[1], virtio_scsi_get_lun(lun));
+}
+
+static void virtio_scsi_init_req(VirtIOSCSI *s, VirtQueue *vq, VirtIOSCSIReq *req)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(s);
+    const size_t zero_skip =
+        offsetof(VirtIOSCSIReq, resp_iov) + sizeof(req->resp_iov);
+
+    req->vq = vq;
+    req->dev = s;
+    qemu_sglist_init(&req->qsgl, DEVICE(s), 8, vdev->dma_as);
+    qemu_iovec_init(&req->resp_iov, 1);
+    memset((uint8_t *)req + zero_skip, 0, sizeof(*req) - zero_skip);
+}
+
+static void virtio_scsi_free_req(VirtIOSCSIReq *req)
+{
+    qemu_iovec_destroy(&req->resp_iov);
+    qemu_sglist_destroy(&req->qsgl);
+    g_free(req);
+}
+
+static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
+{
+    VirtIOSCSI *s = req->dev;
+    VirtQueue *vq = req->vq;
+    VirtIODevice *vdev = VIRTIO_DEVICE(s);
+
+    qemu_iovec_from_buf(&req->resp_iov, 0, &req->resp, req->resp_size);
+    virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
+    if (s->dataplane_started && !s->dataplane_fenced) {
+        virtio_notify_irqfd(vdev, vq);
+    } else {
+        virtio_notify(vdev, vq);
+    }
+
+    if (req->sreq) {
+        req->sreq->hba_private = NULL;
+        scsi_req_unref(req->sreq);
+    }
+    virtio_scsi_free_req(req);
+}
+
+static void virtio_scsi_bad_req(VirtIOSCSIReq *req)
+{
+    virtio_error(VIRTIO_DEVICE(req->dev), "wrong size for virtio-scsi headers");
+    virtqueue_detach_element(req->vq, &req->elem, 0);
+    virtio_scsi_free_req(req);
+}
+
+static size_t qemu_sgl_concat(VirtIOSCSIReq *req, struct iovec *iov,
+                              hwaddr *addr, int num, size_t skip)
+{
+    QEMUSGList *qsgl = &req->qsgl;
+    size_t copied = 0;
+
+    while (num) {
+        if (skip >= iov->iov_len) {
+            skip -= iov->iov_len;
+        } else {
+            qemu_sglist_add(qsgl, *addr + skip, iov->iov_len - skip);
+            copied += iov->iov_len - skip;
+            skip = 0;
+        }
+        iov++;
+        addr++;
+        num--;
+    }
+
+    assert(skip == 0);
+    return copied;
+}
+
+static int virtio_scsi_parse_req(VirtIOSCSIReq *req,
+                                 unsigned req_size, unsigned resp_size)
+{
+    VirtIODevice *vdev = (VirtIODevice *) req->dev;
+    size_t in_size, out_size;
+
+    if (iov_to_buf(req->elem.out_sg, req->elem.out_num, 0,
+                   &req->req, req_size) < req_size) {
+        return -EINVAL;
+    }
+
+    if (qemu_iovec_concat_iov(&req->resp_iov,
+                              req->elem.in_sg, req->elem.in_num, 0,
+                              resp_size) < resp_size) {
+        return -EINVAL;
+    }
+
+    req->resp_size = resp_size;
+
+    /* Old BIOSes left some padding by mistake after the req_size/resp_size.
+     * As a workaround, always consider the first buffer as the virtio-scsi
+     * request/response, making the payload start at the second element
+     * of the iovec.
+     *
+     * The actual length of the response header, stored in req->resp_size,
+     * does not change.
+     *
+     * TODO: always disable this workaround for virtio 1.0 devices.
+     */
+    if (!virtio_vdev_has_feature(vdev, VIRTIO_F_ANY_LAYOUT)) {
+        if (req->elem.out_num) {
+            req_size = req->elem.out_sg[0].iov_len;
+        }
+        if (req->elem.in_num) {
+            resp_size = req->elem.in_sg[0].iov_len;
+        }
+    }
+
+    out_size = qemu_sgl_concat(req, req->elem.out_sg,
+                               &req->elem.out_addr[0], req->elem.out_num,
+                               req_size);
+    in_size = qemu_sgl_concat(req, req->elem.in_sg,
+                              &req->elem.in_addr[0], req->elem.in_num,
+                              resp_size);
+
+    if (out_size && in_size) {
+        return -ENOTSUP;
+    }
+
+    if (out_size) {
+        req->mode = SCSI_XFER_TO_DEV;
+    } else if (in_size) {
+        req->mode = SCSI_XFER_FROM_DEV;
+    }
+
+    return 0;
+}
+
+static VirtIOSCSIReq *virtio_scsi_pop_req(VirtIOSCSI *s, VirtQueue *vq)
+{
+    VirtIOSCSICommon *vs = (VirtIOSCSICommon *)s;
+    VirtIOSCSIReq *req;
+
+    req = virtqueue_pop(vq, sizeof(VirtIOSCSIReq) + vs->cdb_size);
+    if (!req) {
+        return NULL;
+    }
+    virtio_scsi_init_req(s, vq, req);
+    return req;
+}
+
+static void virtio_scsi_save_request(QEMUFile *f, SCSIRequest *sreq)
+{
+    VirtIOSCSIReq *req = sreq->hba_private;
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(req->dev);
+    VirtIODevice *vdev = VIRTIO_DEVICE(req->dev);
+    uint32_t n = virtio_get_queue_index(req->vq) - VIRTIO_SCSI_VQ_NUM_FIXED;
+
+    assert(n < vs->conf.num_queues);
+    qemu_put_be32s(f, &n);
+    qemu_put_virtqueue_element(vdev, f, &req->elem);
+}
+
+static void *virtio_scsi_load_request(QEMUFile *f, SCSIRequest *sreq)
+{
+    SCSIBus *bus = sreq->bus;
+    VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+    VirtIODevice *vdev = VIRTIO_DEVICE(s);
+    VirtIOSCSIReq *req;
+    uint32_t n;
+
+    qemu_get_be32s(f, &n);
+    assert(n < vs->conf.num_queues);
+    req = qemu_get_virtqueue_element(vdev, f,
+                                     sizeof(VirtIOSCSIReq) + vs->cdb_size);
+    virtio_scsi_init_req(s, vs->cmd_vqs[n], req);
+
+    if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICmdReq) + vs->cdb_size,
+                              sizeof(VirtIOSCSICmdResp) + vs->sense_size) < 0) {
+        error_report("invalid SCSI request migration data");
+        exit(1);
+    }
+
+    scsi_req_ref(sreq);
+    req->sreq = sreq;
+    if (req->sreq->cmd.mode != SCSI_XFER_NONE) {
+        assert(req->sreq->cmd.mode == req->mode);
+    }
+    return req;
+}
+
+typedef struct {
+    Notifier        notifier;
+    VirtIOSCSIReq  *tmf_req;
+} VirtIOSCSICancelNotifier;
+
+static void virtio_scsi_cancel_notify(Notifier *notifier, void *data)
+{
+    VirtIOSCSICancelNotifier *n = container_of(notifier,
+                                               VirtIOSCSICancelNotifier,
+                                               notifier);
+
+    if (--n->tmf_req->remaining == 0) {
+        VirtIOSCSIReq *req = n->tmf_req;
+
+        trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(req->req.tmf.lun),
+                                   req->req.tmf.tag, req->resp.tmf.response);
+        virtio_scsi_complete_req(req);
+    }
+    g_free(n);
+}
+
+static inline void virtio_scsi_ctx_check(VirtIOSCSI *s, SCSIDevice *d)
+{
+    if (s->dataplane_started && d && blk_is_available(d->conf.blk)) {
+        assert(blk_get_aio_context(d->conf.blk) == s->ctx);
+    }
+}
+
+/* Return 0 if the request is ready to be completed and return to guest;
+ * -EINPROGRESS if the request is submitted and will be completed later, in the
+ *  case of async cancellation. */
+static int virtio_scsi_do_tmf(VirtIOSCSI *s, VirtIOSCSIReq *req)
+{
+    SCSIDevice *d = virtio_scsi_device_get(s, req->req.tmf.lun);
+    SCSIRequest *r, *next;
+    BusChild *kid;
+    int target;
+    int ret = 0;
+
+    virtio_scsi_ctx_check(s, d);
+    /* Here VIRTIO_SCSI_S_OK means "FUNCTION COMPLETE".  */
+    req->resp.tmf.response = VIRTIO_SCSI_S_OK;
+
+    /*
+     * req->req.tmf has the QEMU_PACKED attribute. Don't use virtio_tswap32s()
+     * to avoid compiler errors.
+     */
+    req->req.tmf.subtype =
+        virtio_tswap32(VIRTIO_DEVICE(s), req->req.tmf.subtype);
+
+    trace_virtio_scsi_tmf_req(virtio_scsi_get_lun(req->req.tmf.lun),
+                              req->req.tmf.tag, req->req.tmf.subtype);
+
+    switch (req->req.tmf.subtype) {
+    case VIRTIO_SCSI_T_TMF_ABORT_TASK:
+    case VIRTIO_SCSI_T_TMF_QUERY_TASK:
+        if (!d) {
+            goto fail;
+        }
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
+            goto incorrect_lun;
+        }
+        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
+            VirtIOSCSIReq *cmd_req = r->hba_private;
+            if (cmd_req && cmd_req->req.cmd.tag == req->req.tmf.tag) {
+                break;
+            }
+        }
+        if (r) {
+            /*
+             * Assert that the request has not been completed yet, we
+             * check for it in the loop above.
+             */
+            assert(r->hba_private);
+            if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK) {
+                /* "If the specified command is present in the task set, then
+                 * return a service response set to FUNCTION SUCCEEDED".
+                 */
+                req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
+            } else {
+                VirtIOSCSICancelNotifier *notifier;
+
+                req->remaining = 1;
+                notifier = g_new(VirtIOSCSICancelNotifier, 1);
+                notifier->tmf_req = req;
+                notifier->notifier.notify = virtio_scsi_cancel_notify;
+                scsi_req_cancel_async(r, &notifier->notifier);
+                ret = -EINPROGRESS;
+            }
+        }
+        break;
+
+    case VIRTIO_SCSI_T_TMF_LOGICAL_UNIT_RESET:
+        if (!d) {
+            goto fail;
+        }
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
+            goto incorrect_lun;
+        }
+        s->resetting++;
+        device_cold_reset(&d->qdev);
+        s->resetting--;
+        break;
+
+    case VIRTIO_SCSI_T_TMF_ABORT_TASK_SET:
+    case VIRTIO_SCSI_T_TMF_CLEAR_TASK_SET:
+    case VIRTIO_SCSI_T_TMF_QUERY_TASK_SET:
+        if (!d) {
+            goto fail;
+        }
+        if (d->lun != virtio_scsi_get_lun(req->req.tmf.lun)) {
+            goto incorrect_lun;
+        }
+
+        /* Add 1 to "remaining" until virtio_scsi_do_tmf returns.
+         * This way, if the bus starts calling back to the notifiers
+         * even before we finish the loop, virtio_scsi_cancel_notify
+         * will not complete the TMF too early.
+         */
+        req->remaining = 1;
+        QTAILQ_FOREACH_SAFE(r, &d->requests, next, next) {
+            if (r->hba_private) {
+                if (req->req.tmf.subtype == VIRTIO_SCSI_T_TMF_QUERY_TASK_SET) {
+                    /* "If there is any command present in the task set, then
+                     * return a service response set to FUNCTION SUCCEEDED".
+                     */
+                    req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_SUCCEEDED;
+                    break;
+                } else {
+                    VirtIOSCSICancelNotifier *notifier;
+
+                    req->remaining++;
+                    notifier = g_new(VirtIOSCSICancelNotifier, 1);
+                    notifier->notifier.notify = virtio_scsi_cancel_notify;
+                    notifier->tmf_req = req;
+                    scsi_req_cancel_async(r, &notifier->notifier);
+                }
+            }
+        }
+        if (--req->remaining > 0) {
+            ret = -EINPROGRESS;
+        }
+        break;
+
+    case VIRTIO_SCSI_T_TMF_I_T_NEXUS_RESET:
+        target = req->req.tmf.lun[1];
+        s->resetting++;
+
+        rcu_read_lock();
+        QTAILQ_FOREACH_RCU(kid, &s->bus.qbus.children, sibling) {
+            SCSIDevice *d1 = SCSI_DEVICE(kid->child);
+            if (d1->channel == 0 && d1->id == target) {
+                device_cold_reset(&d1->qdev);
+            }
+        }
+        rcu_read_unlock();
+
+        s->resetting--;
+        break;
+
+    case VIRTIO_SCSI_T_TMF_CLEAR_ACA:
+    default:
+        req->resp.tmf.response = VIRTIO_SCSI_S_FUNCTION_REJECTED;
+        break;
+    }
+
+    object_unref(OBJECT(d));
+    return ret;
+
+incorrect_lun:
+    req->resp.tmf.response = VIRTIO_SCSI_S_INCORRECT_LUN;
+    object_unref(OBJECT(d));
+    return ret;
+
+fail:
+    req->resp.tmf.response = VIRTIO_SCSI_S_BAD_TARGET;
+    object_unref(OBJECT(d));
+    return ret;
+}
+
+static void virtio_scsi_handle_ctrl_req(VirtIOSCSI *s, VirtIOSCSIReq *req)
+{
+    VirtIODevice *vdev = (VirtIODevice *)s;
+    uint32_t type;
+    int r = 0;
+
+    if (iov_to_buf(req->elem.out_sg, req->elem.out_num, 0,
+                &type, sizeof(type)) < sizeof(type)) {
+        virtio_scsi_bad_req(req);
+        return;
+    }
+
+    virtio_tswap32s(vdev, &type);
+    if (type == VIRTIO_SCSI_T_TMF) {
+        if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlTMFReq),
+                    sizeof(VirtIOSCSICtrlTMFResp)) < 0) {
+            virtio_scsi_bad_req(req);
+            return;
+        } else {
+            r = virtio_scsi_do_tmf(s, req);
+        }
+
+    } else if (type == VIRTIO_SCSI_T_AN_QUERY ||
+               type == VIRTIO_SCSI_T_AN_SUBSCRIBE) {
+        if (virtio_scsi_parse_req(req, sizeof(VirtIOSCSICtrlANReq),
+                    sizeof(VirtIOSCSICtrlANResp)) < 0) {
+            virtio_scsi_bad_req(req);
+            return;
+        } else {
+            req->req.an.event_requested =
+                virtio_tswap32(VIRTIO_DEVICE(s), req->req.an.event_requested);
+            trace_virtio_scsi_an_req(virtio_scsi_get_lun(req->req.an.lun),
+                                     req->req.an.event_requested);
+            req->resp.an.event_actual = 0;
+            req->resp.an.response = VIRTIO_SCSI_S_OK;
+        }
+    }
+    if (r == 0) {
+        if (type == VIRTIO_SCSI_T_TMF)
+            trace_virtio_scsi_tmf_resp(virtio_scsi_get_lun(req->req.tmf.lun),
+                                       req->req.tmf.tag,
+                                       req->resp.tmf.response);
+        else if (type == VIRTIO_SCSI_T_AN_QUERY ||
+                 type == VIRTIO_SCSI_T_AN_SUBSCRIBE)
+            trace_virtio_scsi_an_resp(virtio_scsi_get_lun(req->req.an.lun),
+                                      req->resp.an.response);
+        virtio_scsi_complete_req(req);
+    } else {
+        assert(r == -EINPROGRESS);
+    }
+}
+
+static void virtio_scsi_handle_ctrl_vq(VirtIOSCSI *s, VirtQueue *vq)
+{
+    VirtIOSCSIReq *req;
+
+    while ((req = virtio_scsi_pop_req(s, vq))) {
+        virtio_scsi_handle_ctrl_req(s, req);
+    }
+}
+
+/*
+ * If dataplane is configured but not yet started, do so now and return true on
+ * success.
+ *
+ * Dataplane is started by the core virtio code but virtqueue handler functions
+ * can also be invoked when a guest kicks before DRIVER_OK, so this helper
+ * function helps us deal with manually starting ioeventfd in that case.
+ */
+static bool virtio_scsi_defer_to_dataplane(VirtIOSCSI *s)
+{
+    if (!s->ctx || s->dataplane_started) {
+        return false;
+    }
+
+    virtio_device_start_ioeventfd(&s->parent_obj.parent_obj);
+    return !s->dataplane_fenced;
+}
+
+static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIOSCSI *s = (VirtIOSCSI *)vdev;
+
+    if (virtio_scsi_defer_to_dataplane(s)) {
+        return;
+    }
+
+    virtio_scsi_acquire(s);
+    virtio_scsi_handle_ctrl_vq(s, vq);
+    virtio_scsi_release(s);
+}
+
+static void virtio_scsi_complete_cmd_req(VirtIOSCSIReq *req)
+{
+    trace_virtio_scsi_cmd_resp(virtio_scsi_get_lun(req->req.cmd.lun),
+                               req->req.cmd.tag,
+                               req->resp.cmd.response,
+                               req->resp.cmd.status);
+    /* Sense data is not in req->resp and is copied separately
+     * in virtio_scsi_command_complete.
+     */
+    req->resp_size = sizeof(VirtIOSCSICmdResp);
+    virtio_scsi_complete_req(req);
+}
+
+static void virtio_scsi_command_failed(SCSIRequest *r)
+{
+    VirtIOSCSIReq *req = r->hba_private;
+
+    if (r->io_canceled) {
+        return;
+    }
+
+    req->resp.cmd.status = GOOD;
+    switch (r->host_status) {
+    case SCSI_HOST_NO_LUN:
+        req->resp.cmd.response = VIRTIO_SCSI_S_INCORRECT_LUN;
+        break;
+    case SCSI_HOST_BUSY:
+        req->resp.cmd.response = VIRTIO_SCSI_S_BUSY;
+        break;
+    case SCSI_HOST_TIME_OUT:
+    case SCSI_HOST_ABORTED:
+        req->resp.cmd.response = VIRTIO_SCSI_S_ABORTED;
+        break;
+    case SCSI_HOST_BAD_RESPONSE:
+        req->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
+        break;
+    case SCSI_HOST_RESET:
+        req->resp.cmd.response = VIRTIO_SCSI_S_RESET;
+        break;
+    case SCSI_HOST_TRANSPORT_DISRUPTED:
+        req->resp.cmd.response = VIRTIO_SCSI_S_TRANSPORT_FAILURE;
+        break;
+    case SCSI_HOST_TARGET_FAILURE:
+        req->resp.cmd.response = VIRTIO_SCSI_S_TARGET_FAILURE;
+        break;
+    case SCSI_HOST_RESERVATION_ERROR:
+        req->resp.cmd.response = VIRTIO_SCSI_S_NEXUS_FAILURE;
+        break;
+    case SCSI_HOST_ALLOCATION_FAILURE:
+    case SCSI_HOST_MEDIUM_ERROR:
+    case SCSI_HOST_ERROR:
+    default:
+        req->resp.cmd.response = VIRTIO_SCSI_S_FAILURE;
+        break;
+    }
+    virtio_scsi_complete_cmd_req(req);
+}
+
+static void virtio_scsi_command_complete(SCSIRequest *r, size_t resid)
+{
+    VirtIOSCSIReq *req = r->hba_private;
+    uint8_t sense[SCSI_SENSE_BUF_SIZE];
+    uint32_t sense_len;
+    VirtIODevice *vdev = VIRTIO_DEVICE(req->dev);
+
+    if (r->io_canceled) {
+        return;
+    }
+
+    req->resp.cmd.response = VIRTIO_SCSI_S_OK;
+    req->resp.cmd.status = r->status;
+    if (req->resp.cmd.status == GOOD) {
+        req->resp.cmd.resid = virtio_tswap32(vdev, resid);
+    } else {
+        req->resp.cmd.resid = 0;
+        sense_len = scsi_req_get_sense(r, sense, sizeof(sense));
+        sense_len = MIN(sense_len, req->resp_iov.size - sizeof(req->resp.cmd));
+        qemu_iovec_from_buf(&req->resp_iov, sizeof(req->resp.cmd),
+                            sense, sense_len);
+        req->resp.cmd.sense_len = virtio_tswap32(vdev, sense_len);
+    }
+    virtio_scsi_complete_cmd_req(req);
+}
+
+static int virtio_scsi_parse_cdb(SCSIDevice *dev, SCSICommand *cmd,
+                                 uint8_t *buf, size_t buf_len,
+                                 void *hba_private)
+{
+    VirtIOSCSIReq *req = hba_private;
+
+    if (cmd->len == 0) {
+        cmd->len = MIN(VIRTIO_SCSI_CDB_DEFAULT_SIZE, SCSI_CMD_BUF_SIZE);
+        memcpy(cmd->buf, buf, cmd->len);
+    }
+
+    /* Extract the direction and mode directly from the request, for
+     * host device passthrough.
+     */
+    cmd->xfer = req->qsgl.size;
+    cmd->mode = req->mode;
+    return 0;
+}
+
+static QEMUSGList *virtio_scsi_get_sg_list(SCSIRequest *r)
+{
+    VirtIOSCSIReq *req = r->hba_private;
+
+    return &req->qsgl;
+}
+
+static void virtio_scsi_request_cancelled(SCSIRequest *r)
+{
+    VirtIOSCSIReq *req = r->hba_private;
+
+    if (!req) {
+        return;
+    }
+    if (req->dev->resetting) {
+        req->resp.cmd.response = VIRTIO_SCSI_S_RESET;
+    } else {
+        req->resp.cmd.response = VIRTIO_SCSI_S_ABORTED;
+    }
+    virtio_scsi_complete_cmd_req(req);
+}
+
+static void virtio_scsi_fail_cmd_req(VirtIOSCSIReq *req)
+{
+    req->resp.cmd.response = VIRTIO_SCSI_S_FAILURE;
+    virtio_scsi_complete_cmd_req(req);
+}
+
+static int virtio_scsi_handle_cmd_req_prepare(VirtIOSCSI *s, VirtIOSCSIReq *req)
+{
+    VirtIOSCSICommon *vs = &s->parent_obj;
+    SCSIDevice *d;
+    int rc;
+
+    rc = virtio_scsi_parse_req(req, sizeof(VirtIOSCSICmdReq) + vs->cdb_size,
+                               sizeof(VirtIOSCSICmdResp) + vs->sense_size);
+    if (rc < 0) {
+        if (rc == -ENOTSUP) {
+            virtio_scsi_fail_cmd_req(req);
+            return -ENOTSUP;
+        } else {
+            virtio_scsi_bad_req(req);
+            return -EINVAL;
+        }
+    }
+    trace_virtio_scsi_cmd_req(virtio_scsi_get_lun(req->req.cmd.lun),
+                              req->req.cmd.tag, req->req.cmd.cdb[0]);
+
+    d = virtio_scsi_device_get(s, req->req.cmd.lun);
+    if (!d) {
+        req->resp.cmd.response = VIRTIO_SCSI_S_BAD_TARGET;
+        virtio_scsi_complete_cmd_req(req);
+        return -ENOENT;
+    }
+    virtio_scsi_ctx_check(s, d);
+    req->sreq = scsi_req_new(d, req->req.cmd.tag,
+                             virtio_scsi_get_lun(req->req.cmd.lun),
+                             req->req.cmd.cdb, vs->cdb_size, req);
+
+    if (req->sreq->cmd.mode != SCSI_XFER_NONE
+        && (req->sreq->cmd.mode != req->mode ||
+            req->sreq->cmd.xfer > req->qsgl.size)) {
+        req->resp.cmd.response = VIRTIO_SCSI_S_OVERRUN;
+        virtio_scsi_complete_cmd_req(req);
+        object_unref(OBJECT(d));
+        return -ENOBUFS;
+    }
+    scsi_req_ref(req->sreq);
+    blk_io_plug(d->conf.blk);
+    object_unref(OBJECT(d));
+    return 0;
+}
+
+static void virtio_scsi_handle_cmd_req_submit(VirtIOSCSI *s, VirtIOSCSIReq *req)
+{
+    SCSIRequest *sreq = req->sreq;
+    if (scsi_req_enqueue(sreq)) {
+        scsi_req_continue(sreq);
+    }
+    blk_io_unplug(sreq->dev->conf.blk);
+    scsi_req_unref(sreq);
+}
+
+static void virtio_scsi_handle_cmd_vq(VirtIOSCSI *s, VirtQueue *vq)
+{
+    VirtIOSCSIReq *req, *next;
+    int ret = 0;
+    bool suppress_notifications = virtio_queue_get_notification(vq);
+
+    QTAILQ_HEAD(, VirtIOSCSIReq) reqs = QTAILQ_HEAD_INITIALIZER(reqs);
+
+    do {
+        if (suppress_notifications) {
+            virtio_queue_set_notification(vq, 0);
+        }
+
+        while ((req = virtio_scsi_pop_req(s, vq))) {
+            ret = virtio_scsi_handle_cmd_req_prepare(s, req);
+            if (!ret) {
+                QTAILQ_INSERT_TAIL(&reqs, req, next);
+            } else if (ret == -EINVAL) {
+                /* The device is broken and shouldn't process any request */
+                while (!QTAILQ_EMPTY(&reqs)) {
+                    req = QTAILQ_FIRST(&reqs);
+                    QTAILQ_REMOVE(&reqs, req, next);
+                    blk_io_unplug(req->sreq->dev->conf.blk);
+                    scsi_req_unref(req->sreq);
+                    virtqueue_detach_element(req->vq, &req->elem, 0);
+                    virtio_scsi_free_req(req);
+                }
+            }
+        }
+
+        if (suppress_notifications) {
+            virtio_queue_set_notification(vq, 1);
+        }
+    } while (ret != -EINVAL && !virtio_queue_empty(vq));
+
+    QTAILQ_FOREACH_SAFE(req, &reqs, next, next) {
+        virtio_scsi_handle_cmd_req_submit(s, req);
+    }
+}
+
+static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq)
+{
+    /* use non-QOM casts in the data path */
+    VirtIOSCSI *s = (VirtIOSCSI *)vdev;
+
+    if (virtio_scsi_defer_to_dataplane(s)) {
+        return;
+    }
+
+    virtio_scsi_acquire(s);
+    virtio_scsi_handle_cmd_vq(s, vq);
+    virtio_scsi_release(s);
+}
+
+static void virtio_scsi_get_config(VirtIODevice *vdev,
+                                   uint8_t *config)
+{
+    VirtIOSCSIConfig *scsiconf = (VirtIOSCSIConfig *)config;
+    VirtIOSCSICommon *s = VIRTIO_SCSI_COMMON(vdev);
+
+    virtio_stl_p(vdev, &scsiconf->num_queues, s->conf.num_queues);
+    virtio_stl_p(vdev, &scsiconf->seg_max,
+                 s->conf.seg_max_adjust ? s->conf.virtqueue_size - 2 : 128 - 2);
+    virtio_stl_p(vdev, &scsiconf->max_sectors, s->conf.max_sectors);
+    virtio_stl_p(vdev, &scsiconf->cmd_per_lun, s->conf.cmd_per_lun);
+    virtio_stl_p(vdev, &scsiconf->event_info_size, sizeof(VirtIOSCSIEvent));
+    virtio_stl_p(vdev, &scsiconf->sense_size, s->sense_size);
+    virtio_stl_p(vdev, &scsiconf->cdb_size, s->cdb_size);
+    virtio_stw_p(vdev, &scsiconf->max_channel, VIRTIO_SCSI_MAX_CHANNEL);
+    virtio_stw_p(vdev, &scsiconf->max_target, VIRTIO_SCSI_MAX_TARGET);
+    virtio_stl_p(vdev, &scsiconf->max_lun, VIRTIO_SCSI_MAX_LUN);
+}
+
+static void virtio_scsi_set_config(VirtIODevice *vdev,
+                                   const uint8_t *config)
+{
+    VirtIOSCSIConfig *scsiconf = (VirtIOSCSIConfig *)config;
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
+
+    if ((uint32_t) virtio_ldl_p(vdev, &scsiconf->sense_size) >= 65536 ||
+        (uint32_t) virtio_ldl_p(vdev, &scsiconf->cdb_size) >= 256) {
+        virtio_error(vdev,
+                     "bad data written to virtio-scsi configuration space");
+        return;
+    }
+
+    vs->sense_size = virtio_ldl_p(vdev, &scsiconf->sense_size);
+    vs->cdb_size = virtio_ldl_p(vdev, &scsiconf->cdb_size);
+}
+
+static uint64_t virtio_scsi_get_features(VirtIODevice *vdev,
+                                         uint64_t requested_features,
+                                         Error **errp)
+{
+    VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+
+    /* Firstly sync all virtio-scsi possible supported features */
+    requested_features |= s->host_features;
+    return requested_features;
+}
+
+static void virtio_scsi_reset(VirtIODevice *vdev)
+{
+    VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
+
+    assert(!s->dataplane_started);
+    s->resetting++;
+    bus_cold_reset(BUS(&s->bus));
+    s->resetting--;
+
+    vs->sense_size = VIRTIO_SCSI_SENSE_DEFAULT_SIZE;
+    vs->cdb_size = VIRTIO_SCSI_CDB_DEFAULT_SIZE;
+    s->events_dropped = false;
+}
+
+static void virtio_scsi_push_event(VirtIOSCSI *s, SCSIDevice *dev,
+                                   uint32_t event, uint32_t reason)
+{
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(s);
+    VirtIOSCSIReq *req;
+    VirtIOSCSIEvent *evt;
+    VirtIODevice *vdev = VIRTIO_DEVICE(s);
+
+    if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+        return;
+    }
+
+    req = virtio_scsi_pop_req(s, vs->event_vq);
+    if (!req) {
+        s->events_dropped = true;
+        return;
+    }
+
+    if (s->events_dropped) {
+        event |= VIRTIO_SCSI_T_EVENTS_MISSED;
+        s->events_dropped = false;
+    }
+
+    if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) {
+        virtio_scsi_bad_req(req);
+        return;
+    }
+
+    evt = &req->resp.event;
+    memset(evt, 0, sizeof(VirtIOSCSIEvent));
+    evt->event = virtio_tswap32(vdev, event);
+    evt->reason = virtio_tswap32(vdev, reason);
+    if (!dev) {
+        assert(event == VIRTIO_SCSI_T_EVENTS_MISSED);
+    } else {
+        evt->lun[0] = 1;
+        evt->lun[1] = dev->id;
+
+        /* Linux wants us to keep the same encoding we use for REPORT LUNS.  */
+        if (dev->lun >= 256) {
+            evt->lun[2] = (dev->lun >> 8) | 0x40;
+        }
+        evt->lun[3] = dev->lun & 0xFF;
+    }
+    trace_virtio_scsi_event(virtio_scsi_get_lun(evt->lun), event, reason);
+     
+    virtio_scsi_complete_req(req);
+}
+
+static void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq)
+{
+    if (s->events_dropped) {
+        virtio_scsi_push_event(s, NULL, VIRTIO_SCSI_T_NO_EVENT, 0);
+    }
+}
+
+static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+
+    if (virtio_scsi_defer_to_dataplane(s)) {
+        return;
+    }
+
+    virtio_scsi_acquire(s);
+    virtio_scsi_handle_event_vq(s, vq);
+    virtio_scsi_release(s);
+}
+
+static void virtio_scsi_change(SCSIBus *bus, SCSIDevice *dev, SCSISense sense)
+{
+    VirtIOSCSI *s = container_of(bus, VirtIOSCSI, bus);
+    VirtIODevice *vdev = VIRTIO_DEVICE(s);
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_CHANGE) &&
+        dev->type != TYPE_ROM) {
+        virtio_scsi_acquire(s);
+        virtio_scsi_push_event(s, dev, VIRTIO_SCSI_T_PARAM_CHANGE,
+                               sense.asc | (sense.ascq << 8));
+        virtio_scsi_release(s);
+    }
+}
+
+static void virtio_scsi_pre_hotplug(HotplugHandler *hotplug_dev,
+                                    DeviceState *dev, Error **errp)
+{
+    SCSIDevice *sd = SCSI_DEVICE(dev);
+    sd->hba_supports_iothread = true;
+}
+
+static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                                Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
+    VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+    SCSIDevice *sd = SCSI_DEVICE(dev);
+    AioContext *old_context;
+    int ret;
+
+    if (s->ctx && !s->dataplane_fenced) {
+        if (blk_op_is_blocked(sd->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
+            return;
+        }
+        old_context = blk_get_aio_context(sd->conf.blk);
+        aio_context_acquire(old_context);
+        ret = blk_set_aio_context(sd->conf.blk, s->ctx, errp);
+        aio_context_release(old_context);
+        if (ret < 0) {
+            return;
+        }
+    }
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
+        virtio_scsi_acquire(s);
+        virtio_scsi_push_event(s, sd,
+                               VIRTIO_SCSI_T_TRANSPORT_RESET,
+                               VIRTIO_SCSI_EVT_RESET_RESCAN);
+        scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
+        virtio_scsi_release(s);
+    }
+}
+
+static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
+                                  Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
+    VirtIOSCSI *s = VIRTIO_SCSI(vdev);
+    SCSIDevice *sd = SCSI_DEVICE(dev);
+    AioContext *ctx = s->ctx ?: qemu_get_aio_context();
+
+    if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
+        virtio_scsi_acquire(s);
+        virtio_scsi_push_event(s, sd,
+                               VIRTIO_SCSI_T_TRANSPORT_RESET,
+                               VIRTIO_SCSI_EVT_RESET_REMOVED);
+        scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
+        virtio_scsi_release(s);
+    }
+
+    aio_disable_external(ctx);
+    qdev_simple_device_unplug_cb(hotplug_dev, dev, errp);
+    aio_enable_external(ctx);
+
+    if (s->ctx) {
+        virtio_scsi_acquire(s);
+        /* If other users keep the BlockBackend in the iothread, that's ok */
+        blk_set_aio_context(sd->conf.blk, qemu_get_aio_context(), NULL);
+        virtio_scsi_release(s);
+    }
+}
+
+static struct SCSIBusInfo virtio_scsi_scsi_info = {
+    .tcq = true,
+    .max_channel = VIRTIO_SCSI_MAX_CHANNEL,
+    .max_target = VIRTIO_SCSI_MAX_TARGET,
+    .max_lun = VIRTIO_SCSI_MAX_LUN,
+
+    .complete = virtio_scsi_command_complete,
+    .fail = virtio_scsi_command_failed,
+    .cancel = virtio_scsi_request_cancelled,
+    .change = virtio_scsi_change,
+    .parse_cdb = virtio_scsi_parse_cdb,
+    .get_sg_list = virtio_scsi_get_sg_list,
+    .save_request = virtio_scsi_save_request,
+    .load_request = virtio_scsi_load_request,
+};
+
+void virtio_scsi_common_realize(DeviceState *dev,
+                                VirtIOHandleOutput ctrl,
+                                VirtIOHandleOutput evt,
+                                VirtIOHandleOutput cmd,
+                                Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VirtIOSCSICommon *s = VIRTIO_SCSI_COMMON(dev);
+    int i;
+
+    virtio_init(vdev, VIRTIO_ID_SCSI, sizeof(VirtIOSCSIConfig));
+
+    if (s->conf.num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) {
+        s->conf.num_queues = 1;
+    }
+    if (s->conf.num_queues == 0 ||
+            s->conf.num_queues > VIRTIO_QUEUE_MAX - VIRTIO_SCSI_VQ_NUM_FIXED) {
+        error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
+                         "must be a positive integer less than %d.",
+                   s->conf.num_queues,
+                   VIRTIO_QUEUE_MAX - VIRTIO_SCSI_VQ_NUM_FIXED);
+        virtio_cleanup(vdev);
+        return;
+    }
+    if (s->conf.virtqueue_size <= 2) {
+        error_setg(errp, "invalid virtqueue_size property (= %" PRIu32 "), "
+                   "must be > 2", s->conf.virtqueue_size);
+        return;
+    }
+    s->cmd_vqs = g_new0(VirtQueue *, s->conf.num_queues);
+    s->sense_size = VIRTIO_SCSI_SENSE_DEFAULT_SIZE;
+    s->cdb_size = VIRTIO_SCSI_CDB_DEFAULT_SIZE;
+
+    s->ctrl_vq = virtio_add_queue(vdev, s->conf.virtqueue_size, ctrl);
+    s->event_vq = virtio_add_queue(vdev, s->conf.virtqueue_size, evt);
+    for (i = 0; i < s->conf.num_queues; i++) {
+        s->cmd_vqs[i] = virtio_add_queue(vdev, s->conf.virtqueue_size, cmd);
+    }
+}
+
+static void virtio_scsi_device_realize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VirtIOSCSI *s = VIRTIO_SCSI(dev);
+    Error *err = NULL;
+
+    virtio_scsi_common_realize(dev,
+                               virtio_scsi_handle_ctrl,
+                               virtio_scsi_handle_event,
+                               virtio_scsi_handle_cmd,
+                               &err);
+    if (err != NULL) {
+        error_propagate(errp, err);
+        return;
+    }
+
+    scsi_bus_init_named(&s->bus, sizeof(s->bus), dev,
+                       &virtio_scsi_scsi_info, vdev->bus_name);
+    /* override default SCSI bus hotplug-handler, with virtio-scsi's one */
+    qbus_set_hotplug_handler(BUS(&s->bus), OBJECT(dev));
+
+    virtio_scsi_dataplane_setup(s, errp);
+}
+
+void virtio_scsi_common_unrealize(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(dev);
+    int i;
+
+    virtio_delete_queue(vs->ctrl_vq);
+    virtio_delete_queue(vs->event_vq);
+    for (i = 0; i < vs->conf.num_queues; i++) {
+        virtio_delete_queue(vs->cmd_vqs[i]);
+    }
+    g_free(vs->cmd_vqs);
+    virtio_cleanup(vdev);
+}
+
+static void virtio_scsi_device_unrealize(DeviceState *dev)
+{
+    VirtIOSCSI *s = VIRTIO_SCSI(dev);
+
+    qbus_set_hotplug_handler(BUS(&s->bus), NULL);
+    virtio_scsi_common_unrealize(dev);
+}
+
+static Property virtio_scsi_properties[] = {
+    DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues,
+                       VIRTIO_SCSI_AUTO_NUM_QUEUES),
+    DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSI,
+                                         parent_obj.conf.virtqueue_size, 256),
+    DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSI,
+                      parent_obj.conf.seg_max_adjust, true),
+    DEFINE_PROP_UINT32("max_sectors", VirtIOSCSI, parent_obj.conf.max_sectors,
+                                                  0xFFFF),
+    DEFINE_PROP_UINT32("cmd_per_lun", VirtIOSCSI, parent_obj.conf.cmd_per_lun,
+                                                  128),
+    DEFINE_PROP_BIT("hotplug", VirtIOSCSI, host_features,
+                                           VIRTIO_SCSI_F_HOTPLUG, true),
+    DEFINE_PROP_BIT("param_change", VirtIOSCSI, host_features,
+                                                VIRTIO_SCSI_F_CHANGE, true),
+    DEFINE_PROP_LINK("iothread", VirtIOSCSI, parent_obj.conf.iothread,
+                     TYPE_IOTHREAD, IOThread *),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static const VMStateDescription vmstate_virtio_scsi = {
+    .name = "virtio-scsi",
+    .minimum_version_id = 1,
+    .version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_VIRTIO_DEVICE,
+        VMSTATE_END_OF_LIST()
+    },
+};
+
+static void virtio_scsi_common_class_init(ObjectClass *klass, void *data)
+{
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    vdc->get_config = virtio_scsi_get_config;
+    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
+}
+
+static void virtio_scsi_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
+
+    device_class_set_props(dc, virtio_scsi_properties);
+    dc->vmsd = &vmstate_virtio_scsi;
+    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
+    vdc->realize = virtio_scsi_device_realize;
+    vdc->unrealize = virtio_scsi_device_unrealize;
+    vdc->set_config = virtio_scsi_set_config;
+    vdc->get_features = virtio_scsi_get_features;
+    vdc->reset = virtio_scsi_reset;
+    vdc->start_ioeventfd = virtio_scsi_dataplane_start;
+    vdc->stop_ioeventfd = virtio_scsi_dataplane_stop;
+    hc->pre_plug = virtio_scsi_pre_hotplug;
+    hc->plug = virtio_scsi_hotplug;
+    hc->unplug = virtio_scsi_hotunplug;
+}
+
+static const TypeInfo virtio_scsi_common_info = {
+    .name = TYPE_VIRTIO_SCSI_COMMON,
+    .parent = TYPE_VIRTIO_DEVICE,
+    .instance_size = sizeof(VirtIOSCSICommon),
+    .abstract = true,
+    .class_init = virtio_scsi_common_class_init,
+};
+
+static const TypeInfo virtio_scsi_info = {
+    .name = TYPE_VIRTIO_SCSI,
+    .parent = TYPE_VIRTIO_SCSI_COMMON,
+    .instance_size = sizeof(VirtIOSCSI),
+    .class_init = virtio_scsi_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_HOTPLUG_HANDLER },
+        { }
+    }
+};
+
+static void virtio_register_types(void)
+{
+    type_register_static(&virtio_scsi_common_info);
+    type_register_static(&virtio_scsi_info);
+}
+
+type_init(virtio_register_types)