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

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

1 files changed, 1887 insertions, 0 deletions

diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
new file mode 100644
index 00000000..ceceafb2
--- /dev/null
+++ b/hw/scsi/scsi-bus.c
@@ -0,0 +1,1887 @@
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "qemu/module.h"
+#include "qemu/option.h"
+#include "qemu/hw-version.h"
+#include "hw/qdev-properties.h"
+#include "hw/scsi/scsi.h"
+#include "migration/qemu-file-types.h"
+#include "migration/vmstate.h"
+#include "scsi/constants.h"
+#include "sysemu/block-backend.h"
+#include "sysemu/blockdev.h"
+#include "sysemu/sysemu.h"
+#include "sysemu/runstate.h"
+#include "trace.h"
+#include "sysemu/dma.h"
+#include "qemu/cutils.h"
+
+static char *scsibus_get_dev_path(DeviceState *dev);
+static char *scsibus_get_fw_dev_path(DeviceState *dev);
+static void scsi_req_dequeue(SCSIRequest *req);
+static uint8_t *scsi_target_alloc_buf(SCSIRequest *req, size_t len);
+static void scsi_target_free_buf(SCSIRequest *req);
+
+static int next_scsi_bus;
+
+static SCSIDevice *do_scsi_device_find(SCSIBus *bus,
+                                       int channel, int id, int lun,
+                                       bool include_unrealized)
+{
+    BusChild *kid;
+    SCSIDevice *retval = NULL;
+
+    QTAILQ_FOREACH_RCU(kid, &bus->qbus.children, sibling) {
+        DeviceState *qdev = kid->child;
+        SCSIDevice *dev = SCSI_DEVICE(qdev);
+
+        if (dev->channel == channel && dev->id == id) {
+            if (dev->lun == lun) {
+                retval = dev;
+                break;
+            }
+
+            /*
+             * If we don't find exact match (channel/bus/lun),
+             * we will return the first device which matches channel/bus
+             */
+
+            if (!retval) {
+                retval = dev;
+            }
+        }
+    }
+
+    /*
+     * This function might run on the IO thread and we might race against
+     * main thread hot-plugging the device.
+     * We assume that as soon as .realized is set to true we can let
+     * the user access the device.
+     */
+
+    if (retval && !include_unrealized &&
+        !qatomic_load_acquire(&retval->qdev.realized)) {
+        retval = NULL;
+    }
+
+    return retval;
+}
+
+SCSIDevice *scsi_device_find(SCSIBus *bus, int channel, int id, int lun)
+{
+    RCU_READ_LOCK_GUARD();
+    return do_scsi_device_find(bus, channel, id, lun, false);
+}
+
+SCSIDevice *scsi_device_get(SCSIBus *bus, int channel, int id, int lun)
+{
+    SCSIDevice *d;
+    RCU_READ_LOCK_GUARD();
+    d = do_scsi_device_find(bus, channel, id, lun, false);
+    if (d) {
+        object_ref(d);
+    }
+    return d;
+}
+
+static void scsi_device_realize(SCSIDevice *s, Error **errp)
+{
+    SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(s);
+    if (sc->realize) {
+        sc->realize(s, errp);
+    }
+}
+
+static void scsi_device_unrealize(SCSIDevice *s)
+{
+    SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(s);
+    if (sc->unrealize) {
+        sc->unrealize(s);
+    }
+}
+
+int scsi_bus_parse_cdb(SCSIDevice *dev, SCSICommand *cmd, uint8_t *buf,
+                       size_t buf_len, void *hba_private)
+{
+    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, dev->qdev.parent_bus);
+    int rc;
+
+    assert(cmd->len == 0);
+    rc = scsi_req_parse_cdb(dev, cmd, buf, buf_len);
+    if (bus->info->parse_cdb) {
+        rc = bus->info->parse_cdb(dev, cmd, buf, buf_len, hba_private);
+    }
+    return rc;
+}
+
+static SCSIRequest *scsi_device_alloc_req(SCSIDevice *s, uint32_t tag, uint32_t lun,
+                                          uint8_t *buf, void *hba_private)
+{
+    SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(s);
+    if (sc->alloc_req) {
+        return sc->alloc_req(s, tag, lun, buf, hba_private);
+    }
+
+    return NULL;
+}
+
+void scsi_device_unit_attention_reported(SCSIDevice *s)
+{
+    SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(s);
+    if (sc->unit_attention_reported) {
+        sc->unit_attention_reported(s);
+    }
+}
+
+/* Create a scsi bus, and attach devices to it.  */
+void scsi_bus_init_named(SCSIBus *bus, size_t bus_size, DeviceState *host,
+                         const SCSIBusInfo *info, const char *bus_name)
+{
+    qbus_init(bus, bus_size, TYPE_SCSI_BUS, host, bus_name);
+    bus->busnr = next_scsi_bus++;
+    bus->info = info;
+    qbus_set_bus_hotplug_handler(BUS(bus));
+}
+
+static void scsi_dma_restart_bh(void *opaque)
+{
+    SCSIDevice *s = opaque;
+    SCSIRequest *req, *next;
+
+    qemu_bh_delete(s->bh);
+    s->bh = NULL;
+
+    aio_context_acquire(blk_get_aio_context(s->conf.blk));
+    QTAILQ_FOREACH_SAFE(req, &s->requests, next, next) {
+        scsi_req_ref(req);
+        if (req->retry) {
+            req->retry = false;
+            switch (req->cmd.mode) {
+            case SCSI_XFER_FROM_DEV:
+            case SCSI_XFER_TO_DEV:
+                scsi_req_continue(req);
+                break;
+            case SCSI_XFER_NONE:
+                scsi_req_dequeue(req);
+                scsi_req_enqueue(req);
+                break;
+            }
+        }
+        scsi_req_unref(req);
+    }
+    aio_context_release(blk_get_aio_context(s->conf.blk));
+    /* Drop the reference that was acquired in scsi_dma_restart_cb */
+    object_unref(OBJECT(s));
+}
+
+void scsi_req_retry(SCSIRequest *req)
+{
+    /* No need to save a reference, because scsi_dma_restart_bh just
+     * looks at the request list.  */
+    req->retry = true;
+}
+
+static void scsi_dma_restart_cb(void *opaque, bool running, RunState state)
+{
+    SCSIDevice *s = opaque;
+
+    if (!running) {
+        return;
+    }
+    if (!s->bh) {
+        AioContext *ctx = blk_get_aio_context(s->conf.blk);
+        /* The reference is dropped in scsi_dma_restart_bh.*/
+        object_ref(OBJECT(s));
+        s->bh = aio_bh_new(ctx, scsi_dma_restart_bh, s);
+        qemu_bh_schedule(s->bh);
+    }
+}
+
+static bool scsi_bus_is_address_free(SCSIBus *bus,
+				     int channel, int target, int lun,
+				     SCSIDevice **p_dev)
+{
+    SCSIDevice *d;
+
+    RCU_READ_LOCK_GUARD();
+    d = do_scsi_device_find(bus, channel, target, lun, true);
+    if (d && d->lun == lun) {
+        if (p_dev) {
+            *p_dev = d;
+        }
+        return false;
+    }
+    if (p_dev) {
+        *p_dev = NULL;
+    }
+    return true;
+}
+
+static bool scsi_bus_check_address(BusState *qbus, DeviceState *qdev, Error **errp)
+{
+    SCSIDevice *dev = SCSI_DEVICE(qdev);
+    SCSIBus *bus = SCSI_BUS(qbus);
+
+    if (dev->channel > bus->info->max_channel) {
+        error_setg(errp, "bad scsi channel id: %d", dev->channel);
+        return false;
+    }
+    if (dev->id != -1 && dev->id > bus->info->max_target) {
+        error_setg(errp, "bad scsi device id: %d", dev->id);
+        return false;
+    }
+    if (dev->lun != -1 && dev->lun > bus->info->max_lun) {
+        error_setg(errp, "bad scsi device lun: %d", dev->lun);
+        return false;
+    }
+
+    if (dev->id != -1 && dev->lun != -1) {
+        SCSIDevice *d;
+        if (!scsi_bus_is_address_free(bus, dev->channel, dev->id, dev->lun, &d)) {
+            error_setg(errp, "lun already used by '%s'", d->qdev.id);
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static void scsi_qdev_realize(DeviceState *qdev, Error **errp)
+{
+    SCSIDevice *dev = SCSI_DEVICE(qdev);
+    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, dev->qdev.parent_bus);
+    bool is_free;
+    Error *local_err = NULL;
+
+    if (dev->id == -1) {
+        int id = -1;
+        if (dev->lun == -1) {
+            dev->lun = 0;
+        }
+        do {
+            is_free = scsi_bus_is_address_free(bus, dev->channel, ++id, dev->lun, NULL);
+        } while (!is_free && id < bus->info->max_target);
+        if (!is_free) {
+            error_setg(errp, "no free target");
+            return;
+        }
+        dev->id = id;
+    } else if (dev->lun == -1) {
+        int lun = -1;
+        do {
+            is_free = scsi_bus_is_address_free(bus, dev->channel, dev->id, ++lun, NULL);
+        } while (!is_free && lun < bus->info->max_lun);
+        if (!is_free) {
+            error_setg(errp, "no free lun");
+            return;
+        }
+        dev->lun = lun;
+    }
+
+    QTAILQ_INIT(&dev->requests);
+    scsi_device_realize(dev, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+    dev->vmsentry = qdev_add_vm_change_state_handler(DEVICE(dev),
+            scsi_dma_restart_cb, dev);
+}
+
+static void scsi_qdev_unrealize(DeviceState *qdev)
+{
+    SCSIDevice *dev = SCSI_DEVICE(qdev);
+
+    if (dev->vmsentry) {
+        qemu_del_vm_change_state_handler(dev->vmsentry);
+    }
+
+    scsi_device_purge_requests(dev, SENSE_CODE(NO_SENSE));
+
+    scsi_device_unrealize(dev);
+
+    blockdev_mark_auto_del(dev->conf.blk);
+}
+
+/* handle legacy '-drive if=scsi,...' cmd line args */
+SCSIDevice *scsi_bus_legacy_add_drive(SCSIBus *bus, BlockBackend *blk,
+                                      int unit, bool removable, int bootindex,
+                                      bool share_rw,
+                                      BlockdevOnError rerror,
+                                      BlockdevOnError werror,
+                                      const char *serial, Error **errp)
+{
+    const char *driver;
+    char *name;
+    DeviceState *dev;
+    DriveInfo *dinfo;
+
+    if (blk_is_sg(blk)) {
+        driver = "scsi-generic";
+    } else {
+        dinfo = blk_legacy_dinfo(blk);
+        if (dinfo && dinfo->media_cd) {
+            driver = "scsi-cd";
+        } else {
+            driver = "scsi-hd";
+        }
+    }
+    dev = qdev_new(driver);
+    name = g_strdup_printf("legacy[%d]", unit);
+    object_property_add_child(OBJECT(bus), name, OBJECT(dev));
+    g_free(name);
+
+    qdev_prop_set_uint32(dev, "scsi-id", unit);
+    if (bootindex >= 0) {
+        object_property_set_int(OBJECT(dev), "bootindex", bootindex,
+                                &error_abort);
+    }
+    if (object_property_find(OBJECT(dev), "removable")) {
+        qdev_prop_set_bit(dev, "removable", removable);
+    }
+    if (serial && object_property_find(OBJECT(dev), "serial")) {
+        qdev_prop_set_string(dev, "serial", serial);
+    }
+    if (!qdev_prop_set_drive_err(dev, "drive", blk, errp)) {
+        object_unparent(OBJECT(dev));
+        return NULL;
+    }
+    if (!object_property_set_bool(OBJECT(dev), "share-rw", share_rw, errp)) {
+        object_unparent(OBJECT(dev));
+        return NULL;
+    }
+
+    qdev_prop_set_enum(dev, "rerror", rerror);
+    qdev_prop_set_enum(dev, "werror", werror);
+
+    if (!qdev_realize_and_unref(dev, &bus->qbus, errp)) {
+        object_unparent(OBJECT(dev));
+        return NULL;
+    }
+    return SCSI_DEVICE(dev);
+}
+
+void scsi_bus_legacy_handle_cmdline(SCSIBus *bus)
+{
+    Location loc;
+    DriveInfo *dinfo;
+    int unit;
+
+    loc_push_none(&loc);
+    for (unit = 0; unit <= bus->info->max_target; unit++) {
+        dinfo = drive_get(IF_SCSI, bus->busnr, unit);
+        if (dinfo == NULL) {
+            continue;
+        }
+        qemu_opts_loc_restore(dinfo->opts);
+        scsi_bus_legacy_add_drive(bus, blk_by_legacy_dinfo(dinfo),
+                                  unit, false, -1, false,
+                                  BLOCKDEV_ON_ERROR_AUTO,
+                                  BLOCKDEV_ON_ERROR_AUTO,
+                                  NULL, &error_fatal);
+    }
+    loc_pop(&loc);
+}
+
+static int32_t scsi_invalid_field(SCSIRequest *req, uint8_t *buf)
+{
+    scsi_req_build_sense(req, SENSE_CODE(INVALID_FIELD));
+    scsi_req_complete(req, CHECK_CONDITION);
+    return 0;
+}
+
+static const struct SCSIReqOps reqops_invalid_field = {
+    .size         = sizeof(SCSIRequest),
+    .send_command = scsi_invalid_field
+};
+
+/* SCSIReqOps implementation for invalid commands.  */
+
+static int32_t scsi_invalid_command(SCSIRequest *req, uint8_t *buf)
+{
+    scsi_req_build_sense(req, SENSE_CODE(INVALID_OPCODE));
+    scsi_req_complete(req, CHECK_CONDITION);
+    return 0;
+}
+
+static const struct SCSIReqOps reqops_invalid_opcode = {
+    .size         = sizeof(SCSIRequest),
+    .send_command = scsi_invalid_command
+};
+
+/* SCSIReqOps implementation for unit attention conditions.  */
+
+static int32_t scsi_unit_attention(SCSIRequest *req, uint8_t *buf)
+{
+    if (req->dev->unit_attention.key == UNIT_ATTENTION) {
+        scsi_req_build_sense(req, req->dev->unit_attention);
+    } else if (req->bus->unit_attention.key == UNIT_ATTENTION) {
+        scsi_req_build_sense(req, req->bus->unit_attention);
+    }
+    scsi_req_complete(req, CHECK_CONDITION);
+    return 0;
+}
+
+static const struct SCSIReqOps reqops_unit_attention = {
+    .size         = sizeof(SCSIRequest),
+    .send_command = scsi_unit_attention
+};
+
+/* SCSIReqOps implementation for REPORT LUNS and for commands sent to
+   an invalid LUN.  */
+
+typedef struct SCSITargetReq SCSITargetReq;
+
+struct SCSITargetReq {
+    SCSIRequest req;
+    int len;
+    uint8_t *buf;
+    int buf_len;
+};
+
+static void store_lun(uint8_t *outbuf, int lun)
+{
+    if (lun < 256) {
+        /* Simple logical unit addressing method*/
+        outbuf[0] = 0;
+        outbuf[1] = lun;
+    } else {
+        /* Flat space addressing method */
+        outbuf[0] = 0x40 | (lun >> 8);
+        outbuf[1] = (lun & 255);
+    }
+}
+
+static bool scsi_target_emulate_report_luns(SCSITargetReq *r)
+{
+    BusChild *kid;
+    int channel, id;
+    uint8_t tmp[8] = {0};
+    int len = 0;
+    GByteArray *buf;
+
+    if (r->req.cmd.xfer < 16) {
+        return false;
+    }
+    if (r->req.cmd.buf[2] > 2) {
+        return false;
+    }
+
+    /* reserve space for 63 LUNs*/
+    buf = g_byte_array_sized_new(512);
+
+    channel = r->req.dev->channel;
+    id = r->req.dev->id;
+
+    /* add size (will be updated later to correct value */
+    g_byte_array_append(buf, tmp, 8);
+    len += 8;
+
+    /* add LUN0 */
+    g_byte_array_append(buf, tmp, 8);
+    len += 8;
+
+    WITH_RCU_READ_LOCK_GUARD() {
+        QTAILQ_FOREACH_RCU(kid, &r->req.bus->qbus.children, sibling) {
+            DeviceState *qdev = kid->child;
+            SCSIDevice *dev = SCSI_DEVICE(qdev);
+
+            if (dev->channel == channel && dev->id == id && dev->lun != 0) {
+                store_lun(tmp, dev->lun);
+                g_byte_array_append(buf, tmp, 8);
+                len += 8;
+            }
+        }
+    }
+
+    r->buf_len = len;
+    r->buf = g_byte_array_free(buf, FALSE);
+    r->len = MIN(len, r->req.cmd.xfer & ~7);
+
+    /* store the LUN list length */
+    stl_be_p(&r->buf[0], len - 8);
+    return true;
+}
+
+static bool scsi_target_emulate_inquiry(SCSITargetReq *r)
+{
+    assert(r->req.dev->lun != r->req.lun);
+
+    scsi_target_alloc_buf(&r->req, SCSI_INQUIRY_LEN);
+
+    if (r->req.cmd.buf[1] & 0x2) {
+        /* Command support data - optional, not implemented */
+        return false;
+    }
+
+    if (r->req.cmd.buf[1] & 0x1) {
+        /* Vital product data */
+        uint8_t page_code = r->req.cmd.buf[2];
+        r->buf[r->len++] = page_code ; /* this page */
+        r->buf[r->len++] = 0x00;
+
+        switch (page_code) {
+        case 0x00: /* Supported page codes, mandatory */
+        {
+            int pages;
+            pages = r->len++;
+            r->buf[r->len++] = 0x00; /* list of supported pages (this page) */
+            r->buf[pages] = r->len - pages - 1; /* number of pages */
+            break;
+        }
+        default:
+            return false;
+        }
+        /* done with EVPD */
+        assert(r->len < r->buf_len);
+        r->len = MIN(r->req.cmd.xfer, r->len);
+        return true;
+    }
+
+    /* Standard INQUIRY data */
+    if (r->req.cmd.buf[2] != 0) {
+        return false;
+    }
+
+    /* PAGE CODE == 0 */
+    r->len = MIN(r->req.cmd.xfer, SCSI_INQUIRY_LEN);
+    memset(r->buf, 0, r->len);
+    if (r->req.lun != 0) {
+        r->buf[0] = TYPE_NO_LUN;
+    } else {
+        r->buf[0] = TYPE_NOT_PRESENT | TYPE_INACTIVE;
+        r->buf[2] = 5; /* Version */
+        r->buf[3] = 2 | 0x10; /* HiSup, response data format */
+        r->buf[4] = r->len - 5; /* Additional Length = (Len - 1) - 4 */
+        r->buf[7] = 0x10 | (r->req.bus->info->tcq ? 0x02 : 0); /* Sync, TCQ.  */
+        memcpy(&r->buf[8], "QEMU    ", 8);
+        memcpy(&r->buf[16], "QEMU TARGET     ", 16);
+        pstrcpy((char *) &r->buf[32], 4, qemu_hw_version());
+    }
+    return true;
+}
+
+static size_t scsi_sense_len(SCSIRequest *req)
+{
+    if (req->dev->type == TYPE_SCANNER)
+        return SCSI_SENSE_LEN_SCANNER;
+    else
+        return SCSI_SENSE_LEN;
+}
+
+static int32_t scsi_target_send_command(SCSIRequest *req, uint8_t *buf)
+{
+    SCSITargetReq *r = DO_UPCAST(SCSITargetReq, req, req);
+    int fixed_sense = (req->cmd.buf[1] & 1) == 0;
+
+    if (req->lun != 0 &&
+        buf[0] != INQUIRY && buf[0] != REQUEST_SENSE) {
+        scsi_req_build_sense(req, SENSE_CODE(LUN_NOT_SUPPORTED));
+        scsi_req_complete(req, CHECK_CONDITION);
+        return 0;
+    }
+    switch (buf[0]) {
+    case REPORT_LUNS:
+        if (!scsi_target_emulate_report_luns(r)) {
+            goto illegal_request;
+        }
+        break;
+    case INQUIRY:
+        if (!scsi_target_emulate_inquiry(r)) {
+            goto illegal_request;
+        }
+        break;
+    case REQUEST_SENSE:
+        scsi_target_alloc_buf(&r->req, scsi_sense_len(req));
+        if (req->lun != 0) {
+            const struct SCSISense sense = SENSE_CODE(LUN_NOT_SUPPORTED);
+
+            r->len = scsi_build_sense_buf(r->buf, req->cmd.xfer,
+                                          sense, fixed_sense);
+        } else {
+            r->len = scsi_device_get_sense(r->req.dev, r->buf,
+                                           MIN(req->cmd.xfer, r->buf_len),
+                                           fixed_sense);
+        }
+        if (r->req.dev->sense_is_ua) {
+            scsi_device_unit_attention_reported(req->dev);
+            r->req.dev->sense_len = 0;
+            r->req.dev->sense_is_ua = false;
+        }
+        break;
+    case TEST_UNIT_READY:
+        break;
+    default:
+        scsi_req_build_sense(req, SENSE_CODE(INVALID_OPCODE));
+        scsi_req_complete(req, CHECK_CONDITION);
+        return 0;
+    illegal_request:
+        scsi_req_build_sense(req, SENSE_CODE(INVALID_FIELD));
+        scsi_req_complete(req, CHECK_CONDITION);
+        return 0;
+    }
+
+    if (!r->len) {
+        scsi_req_complete(req, GOOD);
+    }
+    return r->len;
+}
+
+static void scsi_target_read_data(SCSIRequest *req)
+{
+    SCSITargetReq *r = DO_UPCAST(SCSITargetReq, req, req);
+    uint32_t n;
+
+    n = r->len;
+    if (n > 0) {
+        r->len = 0;
+        scsi_req_data(&r->req, n);
+    } else {
+        scsi_req_complete(&r->req, GOOD);
+    }
+}
+
+static uint8_t *scsi_target_get_buf(SCSIRequest *req)
+{
+    SCSITargetReq *r = DO_UPCAST(SCSITargetReq, req, req);
+
+    return r->buf;
+}
+
+static uint8_t *scsi_target_alloc_buf(SCSIRequest *req, size_t len)
+{
+    SCSITargetReq *r = DO_UPCAST(SCSITargetReq, req, req);
+
+    r->buf = g_malloc(len);
+    r->buf_len = len;
+
+    return r->buf;
+}
+
+static void scsi_target_free_buf(SCSIRequest *req)
+{
+    SCSITargetReq *r = DO_UPCAST(SCSITargetReq, req, req);
+
+    g_free(r->buf);
+}
+
+static const struct SCSIReqOps reqops_target_command = {
+    .size         = sizeof(SCSITargetReq),
+    .send_command = scsi_target_send_command,
+    .read_data    = scsi_target_read_data,
+    .get_buf      = scsi_target_get_buf,
+    .free_req     = scsi_target_free_buf,
+};
+
+
+SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d,
+                            uint32_t tag, uint32_t lun, void *hba_private)
+{
+    SCSIRequest *req;
+    SCSIBus *bus = scsi_bus_from_device(d);
+    BusState *qbus = BUS(bus);
+    const int memset_off = offsetof(SCSIRequest, sense)
+                           + sizeof(req->sense);
+
+    req = g_malloc(reqops->size);
+    memset((uint8_t *)req + memset_off, 0, reqops->size - memset_off);
+    req->refcount = 1;
+    req->bus = bus;
+    req->dev = d;
+    req->tag = tag;
+    req->lun = lun;
+    req->hba_private = hba_private;
+    req->status = -1;
+    req->host_status = -1;
+    req->ops = reqops;
+    object_ref(OBJECT(d));
+    object_ref(OBJECT(qbus->parent));
+    notifier_list_init(&req->cancel_notifiers);
+    trace_scsi_req_alloc(req->dev->id, req->lun, req->tag);
+    return req;
+}
+
+SCSIRequest *scsi_req_new(SCSIDevice *d, uint32_t tag, uint32_t lun,
+                          uint8_t *buf, size_t buf_len, void *hba_private)
+{
+    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, d->qdev.parent_bus);
+    const SCSIReqOps *ops;
+    SCSIDeviceClass *sc = SCSI_DEVICE_GET_CLASS(d);
+    SCSIRequest *req;
+    SCSICommand cmd = { .len = 0 };
+    int ret;
+
+    if (buf_len == 0) {
+        trace_scsi_req_parse_bad(d->id, lun, tag, 0);
+        goto invalid_opcode;
+    }
+
+    if ((d->unit_attention.key == UNIT_ATTENTION ||
+         bus->unit_attention.key == UNIT_ATTENTION) &&
+        (buf[0] != INQUIRY &&
+         buf[0] != REPORT_LUNS &&
+         buf[0] != GET_CONFIGURATION &&
+         buf[0] != GET_EVENT_STATUS_NOTIFICATION &&
+
+         /*
+          * If we already have a pending unit attention condition,
+          * report this one before triggering another one.
+          */
+         !(buf[0] == REQUEST_SENSE && d->sense_is_ua))) {
+        ops = &reqops_unit_attention;
+    } else if (lun != d->lun ||
+               buf[0] == REPORT_LUNS ||
+               (buf[0] == REQUEST_SENSE && d->sense_len)) {
+        ops = &reqops_target_command;
+    } else {
+        ops = NULL;
+    }
+
+    if (ops != NULL || !sc->parse_cdb) {
+        ret = scsi_req_parse_cdb(d, &cmd, buf, buf_len);
+    } else {
+        ret = sc->parse_cdb(d, &cmd, buf, buf_len, hba_private);
+    }
+
+    if (ret != 0) {
+        trace_scsi_req_parse_bad(d->id, lun, tag, buf[0]);
+invalid_opcode:
+        req = scsi_req_alloc(&reqops_invalid_opcode, d, tag, lun, hba_private);
+    } else {
+        assert(cmd.len != 0);
+        trace_scsi_req_parsed(d->id, lun, tag, buf[0],
+                              cmd.mode, cmd.xfer);
+        if (cmd.lba != -1) {
+            trace_scsi_req_parsed_lba(d->id, lun, tag, buf[0],
+                                      cmd.lba);
+        }
+
+        if (cmd.xfer > INT32_MAX) {
+            req = scsi_req_alloc(&reqops_invalid_field, d, tag, lun, hba_private);
+        } else if (ops) {
+            req = scsi_req_alloc(ops, d, tag, lun, hba_private);
+        } else {
+            req = scsi_device_alloc_req(d, tag, lun, buf, hba_private);
+        }
+    }
+
+    req->cmd = cmd;
+    req->residual = req->cmd.xfer;
+
+    switch (buf[0]) {
+    case INQUIRY:
+        trace_scsi_inquiry(d->id, lun, tag, cmd.buf[1], cmd.buf[2]);
+        break;
+    case TEST_UNIT_READY:
+        trace_scsi_test_unit_ready(d->id, lun, tag);
+        break;
+    case REPORT_LUNS:
+        trace_scsi_report_luns(d->id, lun, tag);
+        break;
+    case REQUEST_SENSE:
+        trace_scsi_request_sense(d->id, lun, tag);
+        break;
+    default:
+        break;
+    }
+
+    return req;
+}
+
+uint8_t *scsi_req_get_buf(SCSIRequest *req)
+{
+    return req->ops->get_buf(req);
+}
+
+static void scsi_clear_unit_attention(SCSIRequest *req)
+{
+    SCSISense *ua;
+    if (req->dev->unit_attention.key != UNIT_ATTENTION &&
+        req->bus->unit_attention.key != UNIT_ATTENTION) {
+        return;
+    }
+
+    /*
+     * If an INQUIRY command enters the enabled command state,
+     * the device server shall [not] clear any unit attention condition;
+     * See also MMC-6, paragraphs 6.5 and 6.6.2.
+     */
+    if (req->cmd.buf[0] == INQUIRY ||
+        req->cmd.buf[0] == GET_CONFIGURATION ||
+        req->cmd.buf[0] == GET_EVENT_STATUS_NOTIFICATION) {
+        return;
+    }
+
+    if (req->dev->unit_attention.key == UNIT_ATTENTION) {
+        ua = &req->dev->unit_attention;
+    } else {
+        ua = &req->bus->unit_attention;
+    }
+
+    /*
+     * If a REPORT LUNS command enters the enabled command state, [...]
+     * the device server shall clear any pending unit attention condition
+     * with an additional sense code of REPORTED LUNS DATA HAS CHANGED.
+     */
+    if (req->cmd.buf[0] == REPORT_LUNS &&
+        !(ua->asc == SENSE_CODE(REPORTED_LUNS_CHANGED).asc &&
+          ua->ascq == SENSE_CODE(REPORTED_LUNS_CHANGED).ascq)) {
+        return;
+    }
+
+    *ua = SENSE_CODE(NO_SENSE);
+}
+
+int scsi_req_get_sense(SCSIRequest *req, uint8_t *buf, int len)
+{
+    int ret;
+
+    assert(len >= 14);
+    if (!req->sense_len) {
+        return 0;
+    }
+
+    ret = scsi_convert_sense(req->sense, req->sense_len, buf, len, true);
+
+    /*
+     * FIXME: clearing unit attention conditions upon autosense should be done
+     * only if the UA_INTLCK_CTRL field in the Control mode page is set to 00b
+     * (SAM-5, 5.14).
+     *
+     * We assume UA_INTLCK_CTRL to be 00b for HBAs that support autosense, and
+     * 10b for HBAs that do not support it (do not call scsi_req_get_sense).
+     * Here we handle unit attention clearing for UA_INTLCK_CTRL == 00b.
+     */
+    if (req->dev->sense_is_ua) {
+        scsi_device_unit_attention_reported(req->dev);
+        req->dev->sense_len = 0;
+        req->dev->sense_is_ua = false;
+    }
+    return ret;
+}
+
+int scsi_device_get_sense(SCSIDevice *dev, uint8_t *buf, int len, bool fixed)
+{
+    return scsi_convert_sense(dev->sense, dev->sense_len, buf, len, fixed);
+}
+
+void scsi_req_build_sense(SCSIRequest *req, SCSISense sense)
+{
+    trace_scsi_req_build_sense(req->dev->id, req->lun, req->tag,
+                               sense.key, sense.asc, sense.ascq);
+    req->sense_len = scsi_build_sense(req->sense, sense);
+}
+
+static void scsi_req_enqueue_internal(SCSIRequest *req)
+{
+    assert(!req->enqueued);
+    scsi_req_ref(req);
+    if (req->bus->info->get_sg_list) {
+        req->sg = req->bus->info->get_sg_list(req);
+    } else {
+        req->sg = NULL;
+    }
+    req->enqueued = true;
+    QTAILQ_INSERT_TAIL(&req->dev->requests, req, next);
+}
+
+int32_t scsi_req_enqueue(SCSIRequest *req)
+{
+    int32_t rc;
+
+    assert(!req->retry);
+    scsi_req_enqueue_internal(req);
+    scsi_req_ref(req);
+    rc = req->ops->send_command(req, req->cmd.buf);
+    scsi_req_unref(req);
+    return rc;
+}
+
+static void scsi_req_dequeue(SCSIRequest *req)
+{
+    trace_scsi_req_dequeue(req->dev->id, req->lun, req->tag);
+    req->retry = false;
+    if (req->enqueued) {
+        QTAILQ_REMOVE(&req->dev->requests, req, next);
+        req->enqueued = false;
+        scsi_req_unref(req);
+    }
+}
+
+static int scsi_get_performance_length(int num_desc, int type, int data_type)
+{
+    /* MMC-6, paragraph 6.7.  */
+    switch (type) {
+    case 0:
+        if ((data_type & 3) == 0) {
+            /* Each descriptor is as in Table 295 - Nominal performance.  */
+            return 16 * num_desc + 8;
+        } else {
+            /* Each descriptor is as in Table 296 - Exceptions.  */
+            return 6 * num_desc + 8;
+        }
+    case 1:
+    case 4:
+    case 5:
+        return 8 * num_desc + 8;
+    case 2:
+        return 2048 * num_desc + 8;
+    case 3:
+        return 16 * num_desc + 8;
+    default:
+        return 8;
+    }
+}
+
+static int ata_passthrough_xfer_unit(SCSIDevice *dev, uint8_t *buf)
+{
+    int byte_block = (buf[2] >> 2) & 0x1;
+    int type = (buf[2] >> 4) & 0x1;
+    int xfer_unit;
+
+    if (byte_block) {
+        if (type) {
+            xfer_unit = dev->blocksize;
+        } else {
+            xfer_unit = 512;
+        }
+    } else {
+        xfer_unit = 1;
+    }
+
+    return xfer_unit;
+}
+
+static int ata_passthrough_12_xfer(SCSIDevice *dev, uint8_t *buf)
+{
+    int length = buf[2] & 0x3;
+    int xfer;
+    int unit = ata_passthrough_xfer_unit(dev, buf);
+
+    switch (length) {
+    case 0:
+    case 3: /* USB-specific.  */
+    default:
+        xfer = 0;
+        break;
+    case 1:
+        xfer = buf[3];
+        break;
+    case 2:
+        xfer = buf[4];
+        break;
+    }
+
+    return xfer * unit;
+}
+
+static int ata_passthrough_16_xfer(SCSIDevice *dev, uint8_t *buf)
+{
+    int extend = buf[1] & 0x1;
+    int length = buf[2] & 0x3;
+    int xfer;
+    int unit = ata_passthrough_xfer_unit(dev, buf);
+
+    switch (length) {
+    case 0:
+    case 3: /* USB-specific.  */
+    default:
+        xfer = 0;
+        break;
+    case 1:
+        xfer = buf[4];
+        xfer |= (extend ? buf[3] << 8 : 0);
+        break;
+    case 2:
+        xfer = buf[6];
+        xfer |= (extend ? buf[5] << 8 : 0);
+        break;
+    }
+
+    return xfer * unit;
+}
+
+static int scsi_req_xfer(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf)
+{
+    cmd->xfer = scsi_cdb_xfer(buf);
+    switch (buf[0]) {
+    case TEST_UNIT_READY:
+    case REWIND:
+    case START_STOP:
+    case SET_CAPACITY:
+    case WRITE_FILEMARKS:
+    case WRITE_FILEMARKS_16:
+    case SPACE:
+    case RESERVE:
+    case RELEASE:
+    case ERASE:
+    case ALLOW_MEDIUM_REMOVAL:
+    case SEEK_10:
+    case SYNCHRONIZE_CACHE:
+    case SYNCHRONIZE_CACHE_16:
+    case LOCATE_16:
+    case LOCK_UNLOCK_CACHE:
+    case SET_CD_SPEED:
+    case SET_LIMITS:
+    case WRITE_LONG_10:
+    case UPDATE_BLOCK:
+    case RESERVE_TRACK:
+    case SET_READ_AHEAD:
+    case PRE_FETCH:
+    case PRE_FETCH_16:
+    case ALLOW_OVERWRITE:
+        cmd->xfer = 0;
+        break;
+    case VERIFY_10:
+    case VERIFY_12:
+    case VERIFY_16:
+        if ((buf[1] & 2) == 0) {
+            cmd->xfer = 0;
+        } else if ((buf[1] & 4) != 0) {
+            cmd->xfer = 1;
+        }
+        cmd->xfer *= dev->blocksize;
+        break;
+    case MODE_SENSE:
+        break;
+    case WRITE_SAME_10:
+    case WRITE_SAME_16:
+        cmd->xfer = buf[1] & 1 ? 0 : dev->blocksize;
+        break;
+    case READ_CAPACITY_10:
+        cmd->xfer = 8;
+        break;
+    case READ_BLOCK_LIMITS:
+        cmd->xfer = 6;
+        break;
+    case SEND_VOLUME_TAG:
+        /* GPCMD_SET_STREAMING from multimedia commands.  */
+        if (dev->type == TYPE_ROM) {
+            cmd->xfer = buf[10] | (buf[9] << 8);
+        } else {
+            cmd->xfer = buf[9] | (buf[8] << 8);
+        }
+        break;
+    case WRITE_6:
+        /* length 0 means 256 blocks */
+        if (cmd->xfer == 0) {
+            cmd->xfer = 256;
+        }
+        /* fall through */
+    case WRITE_10:
+    case WRITE_VERIFY_10:
+    case WRITE_12:
+    case WRITE_VERIFY_12:
+    case WRITE_16:
+    case WRITE_VERIFY_16:
+        cmd->xfer *= dev->blocksize;
+        break;
+    case READ_6:
+    case READ_REVERSE:
+        /* length 0 means 256 blocks */
+        if (cmd->xfer == 0) {
+            cmd->xfer = 256;
+        }
+        /* fall through */
+    case READ_10:
+    case READ_12:
+    case READ_16:
+        cmd->xfer *= dev->blocksize;
+        break;
+    case FORMAT_UNIT:
+        /* MMC mandates the parameter list to be 12-bytes long.  Parameters
+         * for block devices are restricted to the header right now.  */
+        if (dev->type == TYPE_ROM && (buf[1] & 16)) {
+            cmd->xfer = 12;
+        } else {
+            cmd->xfer = (buf[1] & 16) == 0 ? 0 : (buf[1] & 32 ? 8 : 4);
+        }
+        break;
+    case INQUIRY:
+    case RECEIVE_DIAGNOSTIC:
+    case SEND_DIAGNOSTIC:
+        cmd->xfer = buf[4] | (buf[3] << 8);
+        break;
+    case READ_CD:
+    case READ_BUFFER:
+    case WRITE_BUFFER:
+    case SEND_CUE_SHEET:
+        cmd->xfer = buf[8] | (buf[7] << 8) | (buf[6] << 16);
+        break;
+    case PERSISTENT_RESERVE_OUT:
+        cmd->xfer = ldl_be_p(&buf[5]) & 0xffffffffULL;
+        break;
+    case ERASE_12:
+        if (dev->type == TYPE_ROM) {
+            /* MMC command GET PERFORMANCE.  */
+            cmd->xfer = scsi_get_performance_length(buf[9] | (buf[8] << 8),
+                                                    buf[10], buf[1] & 0x1f);
+        }
+        break;
+    case MECHANISM_STATUS:
+    case READ_DVD_STRUCTURE:
+    case SEND_DVD_STRUCTURE:
+    case MAINTENANCE_OUT:
+    case MAINTENANCE_IN:
+        if (dev->type == TYPE_ROM) {
+            /* GPCMD_REPORT_KEY and GPCMD_SEND_KEY from multi media commands */
+            cmd->xfer = buf[9] | (buf[8] << 8);
+        }
+        break;
+    case ATA_PASSTHROUGH_12:
+        if (dev->type == TYPE_ROM) {
+            /* BLANK command of MMC */
+            cmd->xfer = 0;
+        } else {
+            cmd->xfer = ata_passthrough_12_xfer(dev, buf);
+        }
+        break;
+    case ATA_PASSTHROUGH_16:
+        cmd->xfer = ata_passthrough_16_xfer(dev, buf);
+        break;
+    }
+    return 0;
+}
+
+static int scsi_req_stream_xfer(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf)
+{
+    switch (buf[0]) {
+    /* stream commands */
+    case ERASE_12:
+    case ERASE_16:
+        cmd->xfer = 0;
+        break;
+    case READ_6:
+    case READ_REVERSE:
+    case RECOVER_BUFFERED_DATA:
+    case WRITE_6:
+        cmd->xfer = buf[4] | (buf[3] << 8) | (buf[2] << 16);
+        if (buf[1] & 0x01) { /* fixed */
+            cmd->xfer *= dev->blocksize;
+        }
+        break;
+    case READ_16:
+    case READ_REVERSE_16:
+    case VERIFY_16:
+    case WRITE_16:
+        cmd->xfer = buf[14] | (buf[13] << 8) | (buf[12] << 16);
+        if (buf[1] & 0x01) { /* fixed */
+            cmd->xfer *= dev->blocksize;
+        }
+        break;
+    case REWIND:
+    case LOAD_UNLOAD:
+        cmd->xfer = 0;
+        break;
+    case SPACE_16:
+        cmd->xfer = buf[13] | (buf[12] << 8);
+        break;
+    case READ_POSITION:
+        switch (buf[1] & 0x1f) /* operation code */ {
+        case SHORT_FORM_BLOCK_ID:
+        case SHORT_FORM_VENDOR_SPECIFIC:
+            cmd->xfer = 20;
+            break;
+        case LONG_FORM:
+            cmd->xfer = 32;
+            break;
+        case EXTENDED_FORM:
+            cmd->xfer = buf[8] | (buf[7] << 8);
+            break;
+        default:
+            return -1;
+        }
+
+        break;
+    case FORMAT_UNIT:
+        cmd->xfer = buf[4] | (buf[3] << 8);
+        break;
+    /* generic commands */
+    default:
+        return scsi_req_xfer(cmd, dev, buf);
+    }
+    return 0;
+}
+
+static int scsi_req_medium_changer_xfer(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf)
+{
+    switch (buf[0]) {
+    /* medium changer commands */
+    case EXCHANGE_MEDIUM:
+    case INITIALIZE_ELEMENT_STATUS:
+    case INITIALIZE_ELEMENT_STATUS_WITH_RANGE:
+    case MOVE_MEDIUM:
+    case POSITION_TO_ELEMENT:
+        cmd->xfer = 0;
+        break;
+    case READ_ELEMENT_STATUS:
+        cmd->xfer = buf[9] | (buf[8] << 8) | (buf[7] << 16);
+        break;
+
+    /* generic commands */
+    default:
+        return scsi_req_xfer(cmd, dev, buf);
+    }
+    return 0;
+}
+
+static int scsi_req_scanner_length(SCSICommand *cmd, SCSIDevice *dev, uint8_t *buf)
+{
+    switch (buf[0]) {
+    /* Scanner commands */
+    case OBJECT_POSITION:
+        cmd->xfer = 0;
+        break;
+    case SCAN:
+        cmd->xfer = buf[4];
+        break;
+    case READ_10:
+    case SEND:
+    case GET_WINDOW:
+    case SET_WINDOW:
+        cmd->xfer = buf[8] | (buf[7] << 8) | (buf[6] << 16);
+        break;
+    default:
+        /* GET_DATA_BUFFER_STATUS xfer handled by scsi_req_xfer */
+        return scsi_req_xfer(cmd, dev, buf);
+    }
+
+    return 0;
+}
+
+static void scsi_cmd_xfer_mode(SCSICommand *cmd)
+{
+    if (!cmd->xfer) {
+        cmd->mode = SCSI_XFER_NONE;
+        return;
+    }
+    switch (cmd->buf[0]) {
+    case WRITE_6:
+    case WRITE_10:
+    case WRITE_VERIFY_10:
+    case WRITE_12:
+    case WRITE_VERIFY_12:
+    case WRITE_16:
+    case WRITE_VERIFY_16:
+    case VERIFY_10:
+    case VERIFY_12:
+    case VERIFY_16:
+    case COPY:
+    case COPY_VERIFY:
+    case COMPARE:
+    case CHANGE_DEFINITION:
+    case LOG_SELECT:
+    case MODE_SELECT:
+    case MODE_SELECT_10:
+    case SEND_DIAGNOSTIC:
+    case WRITE_BUFFER:
+    case FORMAT_UNIT:
+    case REASSIGN_BLOCKS:
+    case SEARCH_EQUAL:
+    case SEARCH_HIGH:
+    case SEARCH_LOW:
+    case UPDATE_BLOCK:
+    case WRITE_LONG_10:
+    case WRITE_SAME_10:
+    case WRITE_SAME_16:
+    case UNMAP:
+    case SEARCH_HIGH_12:
+    case SEARCH_EQUAL_12:
+    case SEARCH_LOW_12:
+    case MEDIUM_SCAN:
+    case SEND_VOLUME_TAG:
+    case SEND_CUE_SHEET:
+    case SEND_DVD_STRUCTURE:
+    case PERSISTENT_RESERVE_OUT:
+    case MAINTENANCE_OUT:
+    case SET_WINDOW:
+    case SCAN:
+        /* SCAN conflicts with START_STOP.  START_STOP has cmd->xfer set to 0 for
+         * non-scanner devices, so we only get here for SCAN and not for START_STOP.
+         */
+        cmd->mode = SCSI_XFER_TO_DEV;
+        break;
+    case ATA_PASSTHROUGH_12:
+    case ATA_PASSTHROUGH_16:
+        /* T_DIR */
+        cmd->mode = (cmd->buf[2] & 0x8) ?
+                   SCSI_XFER_FROM_DEV : SCSI_XFER_TO_DEV;
+        break;
+    default:
+        cmd->mode = SCSI_XFER_FROM_DEV;
+        break;
+    }
+}
+
+int scsi_req_parse_cdb(SCSIDevice *dev, SCSICommand *cmd, uint8_t *buf,
+                       size_t buf_len)
+{
+    int rc;
+    int len;
+
+    cmd->lba = -1;
+    len = scsi_cdb_length(buf);
+    if (len < 0 || len > buf_len) {
+        return -1;
+    }
+
+    cmd->len = len;
+    switch (dev->type) {
+    case TYPE_TAPE:
+        rc = scsi_req_stream_xfer(cmd, dev, buf);
+        break;
+    case TYPE_MEDIUM_CHANGER:
+        rc = scsi_req_medium_changer_xfer(cmd, dev, buf);
+        break;
+    case TYPE_SCANNER:
+        rc = scsi_req_scanner_length(cmd, dev, buf);
+        break;
+    default:
+        rc = scsi_req_xfer(cmd, dev, buf);
+        break;
+    }
+
+    if (rc != 0)
+        return rc;
+
+    memcpy(cmd->buf, buf, cmd->len);
+    scsi_cmd_xfer_mode(cmd);
+    cmd->lba = scsi_cmd_lba(cmd);
+    return 0;
+}
+
+void scsi_device_report_change(SCSIDevice *dev, SCSISense sense)
+{
+    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, dev->qdev.parent_bus);
+
+    scsi_device_set_ua(dev, sense);
+    if (bus->info->change) {
+        bus->info->change(bus, dev, sense);
+    }
+}
+
+SCSIRequest *scsi_req_ref(SCSIRequest *req)
+{
+    assert(req->refcount > 0);
+    req->refcount++;
+    return req;
+}
+
+void scsi_req_unref(SCSIRequest *req)
+{
+    assert(req->refcount > 0);
+    if (--req->refcount == 0) {
+        BusState *qbus = req->dev->qdev.parent_bus;
+        SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, qbus);
+
+        if (bus->info->free_request && req->hba_private) {
+            bus->info->free_request(bus, req->hba_private);
+        }
+        if (req->ops->free_req) {
+            req->ops->free_req(req);
+        }
+        object_unref(OBJECT(req->dev));
+        object_unref(OBJECT(qbus->parent));
+        g_free(req);
+    }
+}
+
+/* Tell the device that we finished processing this chunk of I/O.  It
+   will start the next chunk or complete the command.  */
+void scsi_req_continue(SCSIRequest *req)
+{
+    if (req->io_canceled) {
+        trace_scsi_req_continue_canceled(req->dev->id, req->lun, req->tag);
+        return;
+    }
+    trace_scsi_req_continue(req->dev->id, req->lun, req->tag);
+    if (req->cmd.mode == SCSI_XFER_TO_DEV) {
+        req->ops->write_data(req);
+    } else {
+        req->ops->read_data(req);
+    }
+}
+
+/* Called by the devices when data is ready for the HBA.  The HBA should
+   start a DMA operation to read or fill the device's data buffer.
+   Once it completes, calling scsi_req_continue will restart I/O.  */
+void scsi_req_data(SCSIRequest *req, int len)
+{
+    uint8_t *buf;
+    if (req->io_canceled) {
+        trace_scsi_req_data_canceled(req->dev->id, req->lun, req->tag, len);
+        return;
+    }
+    trace_scsi_req_data(req->dev->id, req->lun, req->tag, len);
+    assert(req->cmd.mode != SCSI_XFER_NONE);
+    if (!req->sg) {
+        req->residual -= len;
+        req->bus->info->transfer_data(req, len);
+        return;
+    }
+
+    /* If the device calls scsi_req_data and the HBA specified a
+     * scatter/gather list, the transfer has to happen in a single
+     * step.  */
+    assert(!req->dma_started);
+    req->dma_started = true;
+
+    buf = scsi_req_get_buf(req);
+    if (req->cmd.mode == SCSI_XFER_FROM_DEV) {
+        dma_buf_read(buf, len, &req->residual, req->sg,
+                     MEMTXATTRS_UNSPECIFIED);
+    } else {
+        dma_buf_write(buf, len, &req->residual, req->sg,
+                      MEMTXATTRS_UNSPECIFIED);
+    }
+    scsi_req_continue(req);
+}
+
+void scsi_req_print(SCSIRequest *req)
+{
+    FILE *fp = stderr;
+    int i;
+
+    fprintf(fp, "[%s id=%d] %s",
+            req->dev->qdev.parent_bus->name,
+            req->dev->id,
+            scsi_command_name(req->cmd.buf[0]));
+    for (i = 1; i < req->cmd.len; i++) {
+        fprintf(fp, " 0x%02x", req->cmd.buf[i]);
+    }
+    switch (req->cmd.mode) {
+    case SCSI_XFER_NONE:
+        fprintf(fp, " - none\n");
+        break;
+    case SCSI_XFER_FROM_DEV:
+        fprintf(fp, " - from-dev len=%zd\n", req->cmd.xfer);
+        break;
+    case SCSI_XFER_TO_DEV:
+        fprintf(fp, " - to-dev len=%zd\n", req->cmd.xfer);
+        break;
+    default:
+        fprintf(fp, " - Oops\n");
+        break;
+    }
+}
+
+void scsi_req_complete_failed(SCSIRequest *req, int host_status)
+{
+    SCSISense sense;
+    int status;
+
+    assert(req->status == -1 && req->host_status == -1);
+    assert(req->ops != &reqops_unit_attention);
+
+    if (!req->bus->info->fail) {
+        status = scsi_sense_from_host_status(req->host_status, &sense);
+        if (status == CHECK_CONDITION) {
+            scsi_req_build_sense(req, sense);
+        }
+        scsi_req_complete(req, status);
+        return;
+    }
+
+    req->host_status = host_status;
+    scsi_req_ref(req);
+    scsi_req_dequeue(req);
+    req->bus->info->fail(req);
+
+    /* Cancelled requests might end up being completed instead of cancelled */
+    notifier_list_notify(&req->cancel_notifiers, req);
+    scsi_req_unref(req);
+}
+
+void scsi_req_complete(SCSIRequest *req, int status)
+{
+    assert(req->status == -1 && req->host_status == -1);
+    req->status = status;
+    req->host_status = SCSI_HOST_OK;
+
+    assert(req->sense_len <= sizeof(req->sense));
+    if (status == GOOD) {
+        req->sense_len = 0;
+    }
+
+    if (req->sense_len) {
+        memcpy(req->dev->sense, req->sense, req->sense_len);
+        req->dev->sense_len = req->sense_len;
+        req->dev->sense_is_ua = (req->ops == &reqops_unit_attention);
+    } else {
+        req->dev->sense_len = 0;
+        req->dev->sense_is_ua = false;
+    }
+
+    /*
+     * Unit attention state is now stored in the device's sense buffer
+     * if the HBA didn't do autosense.  Clear the pending unit attention
+     * flags.
+     */
+    scsi_clear_unit_attention(req);
+
+    scsi_req_ref(req);
+    scsi_req_dequeue(req);
+    req->bus->info->complete(req, req->residual);
+
+    /* Cancelled requests might end up being completed instead of cancelled */
+    notifier_list_notify(&req->cancel_notifiers, req);
+    scsi_req_unref(req);
+}
+
+/* Called by the devices when the request is canceled. */
+void scsi_req_cancel_complete(SCSIRequest *req)
+{
+    assert(req->io_canceled);
+    if (req->bus->info->cancel) {
+        req->bus->info->cancel(req);
+    }
+    notifier_list_notify(&req->cancel_notifiers, req);
+    scsi_req_unref(req);
+}
+
+/* Cancel @req asynchronously. @notifier is added to @req's cancellation
+ * notifier list, the bus will be notified the requests cancellation is
+ * completed.
+ * */
+void scsi_req_cancel_async(SCSIRequest *req, Notifier *notifier)
+{
+    trace_scsi_req_cancel(req->dev->id, req->lun, req->tag);
+    if (notifier) {
+        notifier_list_add(&req->cancel_notifiers, notifier);
+    }
+    if (req->io_canceled) {
+        /* A blk_aio_cancel_async is pending; when it finishes,
+         * scsi_req_cancel_complete will be called and will
+         * call the notifier we just added.  Just wait for that.
+         */
+        assert(req->aiocb);
+        return;
+    }
+    /* Dropped in scsi_req_cancel_complete.  */
+    scsi_req_ref(req);
+    scsi_req_dequeue(req);
+    req->io_canceled = true;
+    if (req->aiocb) {
+        blk_aio_cancel_async(req->aiocb);
+    } else {
+        scsi_req_cancel_complete(req);
+    }
+}
+
+void scsi_req_cancel(SCSIRequest *req)
+{
+    trace_scsi_req_cancel(req->dev->id, req->lun, req->tag);
+    if (!req->enqueued) {
+        return;
+    }
+    assert(!req->io_canceled);
+    /* Dropped in scsi_req_cancel_complete.  */
+    scsi_req_ref(req);
+    scsi_req_dequeue(req);
+    req->io_canceled = true;
+    if (req->aiocb) {
+        blk_aio_cancel(req->aiocb);
+    } else {
+        scsi_req_cancel_complete(req);
+    }
+}
+
+static int scsi_ua_precedence(SCSISense sense)
+{
+    if (sense.key != UNIT_ATTENTION) {
+        return INT_MAX;
+    }
+    if (sense.asc == 0x29 && sense.ascq == 0x04) {
+        /* DEVICE INTERNAL RESET goes with POWER ON OCCURRED */
+        return 1;
+    } else if (sense.asc == 0x3F && sense.ascq == 0x01) {
+        /* MICROCODE HAS BEEN CHANGED goes with SCSI BUS RESET OCCURRED */
+        return 2;
+    } else if (sense.asc == 0x29 && (sense.ascq == 0x05 || sense.ascq == 0x06)) {
+        /* These two go with "all others". */
+        ;
+    } else if (sense.asc == 0x29 && sense.ascq <= 0x07) {
+        /* POWER ON, RESET OR BUS DEVICE RESET OCCURRED = 0
+         * POWER ON OCCURRED = 1
+         * SCSI BUS RESET OCCURRED = 2
+         * BUS DEVICE RESET FUNCTION OCCURRED = 3
+         * I_T NEXUS LOSS OCCURRED = 7
+         */
+        return sense.ascq;
+    } else if (sense.asc == 0x2F && sense.ascq == 0x01) {
+        /* COMMANDS CLEARED BY POWER LOSS NOTIFICATION  */
+        return 8;
+    }
+    return (sense.asc << 8) | sense.ascq;
+}
+
+void scsi_bus_set_ua(SCSIBus *bus, SCSISense sense)
+{
+    int prec1, prec2;
+    if (sense.key != UNIT_ATTENTION) {
+        return;
+    }
+
+    /*
+     * Override a pre-existing unit attention condition, except for a more
+     * important reset condition.
+     */
+    prec1 = scsi_ua_precedence(bus->unit_attention);
+    prec2 = scsi_ua_precedence(sense);
+    if (prec2 < prec1) {
+        bus->unit_attention = sense;
+    }
+}
+
+void scsi_device_set_ua(SCSIDevice *sdev, SCSISense sense)
+{
+    int prec1, prec2;
+    if (sense.key != UNIT_ATTENTION) {
+        return;
+    }
+    trace_scsi_device_set_ua(sdev->id, sdev->lun, sense.key,
+                             sense.asc, sense.ascq);
+
+    /*
+     * Override a pre-existing unit attention condition, except for a more
+     * important reset condition.
+    */
+    prec1 = scsi_ua_precedence(sdev->unit_attention);
+    prec2 = scsi_ua_precedence(sense);
+    if (prec2 < prec1) {
+        sdev->unit_attention = sense;
+    }
+}
+
+void scsi_device_purge_requests(SCSIDevice *sdev, SCSISense sense)
+{
+    SCSIRequest *req;
+
+    aio_context_acquire(blk_get_aio_context(sdev->conf.blk));
+    while (!QTAILQ_EMPTY(&sdev->requests)) {
+        req = QTAILQ_FIRST(&sdev->requests);
+        scsi_req_cancel_async(req, NULL);
+    }
+    blk_drain(sdev->conf.blk);
+    aio_context_release(blk_get_aio_context(sdev->conf.blk));
+    scsi_device_set_ua(sdev, sense);
+}
+
+static char *scsibus_get_dev_path(DeviceState *dev)
+{
+    SCSIDevice *d = SCSI_DEVICE(dev);
+    DeviceState *hba = dev->parent_bus->parent;
+    char *id;
+    char *path;
+
+    id = qdev_get_dev_path(hba);
+    if (id) {
+        path = g_strdup_printf("%s/%d:%d:%d", id, d->channel, d->id, d->lun);
+    } else {
+        path = g_strdup_printf("%d:%d:%d", d->channel, d->id, d->lun);
+    }
+    g_free(id);
+    return path;
+}
+
+static char *scsibus_get_fw_dev_path(DeviceState *dev)
+{
+    SCSIDevice *d = SCSI_DEVICE(dev);
+    return g_strdup_printf("channel@%x/%s@%x,%x", d->channel,
+                           qdev_fw_name(dev), d->id, d->lun);
+}
+
+/* SCSI request list.  For simplicity, pv points to the whole device */
+
+static int put_scsi_requests(QEMUFile *f, void *pv, size_t size,
+                             const VMStateField *field, JSONWriter *vmdesc)
+{
+    SCSIDevice *s = pv;
+    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, s->qdev.parent_bus);
+    SCSIRequest *req;
+
+    QTAILQ_FOREACH(req, &s->requests, next) {
+        assert(!req->io_canceled);
+        assert(req->status == -1 && req->host_status == -1);
+        assert(req->enqueued);
+
+        qemu_put_sbyte(f, req->retry ? 1 : 2);
+        qemu_put_buffer(f, req->cmd.buf, sizeof(req->cmd.buf));
+        qemu_put_be32s(f, &req->tag);
+        qemu_put_be32s(f, &req->lun);
+        if (bus->info->save_request) {
+            bus->info->save_request(f, req);
+        }
+        if (req->ops->save_request) {
+            req->ops->save_request(f, req);
+        }
+    }
+    qemu_put_sbyte(f, 0);
+
+    return 0;
+}
+
+static int get_scsi_requests(QEMUFile *f, void *pv, size_t size,
+                             const VMStateField *field)
+{
+    SCSIDevice *s = pv;
+    SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, s->qdev.parent_bus);
+    int8_t sbyte;
+
+    while ((sbyte = qemu_get_sbyte(f)) > 0) {
+        uint8_t buf[SCSI_CMD_BUF_SIZE];
+        uint32_t tag;
+        uint32_t lun;
+        SCSIRequest *req;
+
+        qemu_get_buffer(f, buf, sizeof(buf));
+        qemu_get_be32s(f, &tag);
+        qemu_get_be32s(f, &lun);
+        /*
+         * A too-short CDB would have been rejected by scsi_req_new, so just use
+         * SCSI_CMD_BUF_SIZE as the CDB length.
+         */
+        req = scsi_req_new(s, tag, lun, buf, sizeof(buf), NULL);
+        req->retry = (sbyte == 1);
+        if (bus->info->load_request) {
+            req->hba_private = bus->info->load_request(f, req);
+        }
+        if (req->ops->load_request) {
+            req->ops->load_request(f, req);
+        }
+
+        /* Just restart it later.  */
+        scsi_req_enqueue_internal(req);
+
+        /* At this point, the request will be kept alive by the reference
+         * added by scsi_req_enqueue_internal, so we can release our reference.
+         * The HBA of course will add its own reference in the load_request
+         * callback if it needs to hold on the SCSIRequest.
+         */
+        scsi_req_unref(req);
+    }
+
+    return 0;
+}
+
+static const VMStateInfo vmstate_info_scsi_requests = {
+    .name = "scsi-requests",
+    .get  = get_scsi_requests,
+    .put  = put_scsi_requests,
+};
+
+static bool scsi_sense_state_needed(void *opaque)
+{
+    SCSIDevice *s = opaque;
+
+    return s->sense_len > SCSI_SENSE_BUF_SIZE_OLD;
+}
+
+static const VMStateDescription vmstate_scsi_sense_state = {
+    .name = "SCSIDevice/sense",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = scsi_sense_state_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8_SUB_ARRAY(sense, SCSIDevice,
+                                SCSI_SENSE_BUF_SIZE_OLD,
+                                SCSI_SENSE_BUF_SIZE - SCSI_SENSE_BUF_SIZE_OLD),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+const VMStateDescription vmstate_scsi_device = {
+    .name = "SCSIDevice",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT8(unit_attention.key, SCSIDevice),
+        VMSTATE_UINT8(unit_attention.asc, SCSIDevice),
+        VMSTATE_UINT8(unit_attention.ascq, SCSIDevice),
+        VMSTATE_BOOL(sense_is_ua, SCSIDevice),
+        VMSTATE_UINT8_SUB_ARRAY(sense, SCSIDevice, 0, SCSI_SENSE_BUF_SIZE_OLD),
+        VMSTATE_UINT32(sense_len, SCSIDevice),
+        {
+            .name         = "requests",
+            .version_id   = 0,
+            .field_exists = NULL,
+            .size         = 0,   /* ouch */
+            .info         = &vmstate_info_scsi_requests,
+            .flags        = VMS_SINGLE,
+            .offset       = 0,
+        },
+        VMSTATE_END_OF_LIST()
+    },
+    .subsections = (const VMStateDescription*[]) {
+        &vmstate_scsi_sense_state,
+        NULL
+    }
+};
+
+static Property scsi_props[] = {
+    DEFINE_PROP_UINT32("channel", SCSIDevice, channel, 0),
+    DEFINE_PROP_UINT32("scsi-id", SCSIDevice, id, -1),
+    DEFINE_PROP_UINT32("lun", SCSIDevice, lun, -1),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void scsi_device_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *k = DEVICE_CLASS(klass);
+    set_bit(DEVICE_CATEGORY_STORAGE, k->categories);
+    k->bus_type  = TYPE_SCSI_BUS;
+    k->realize   = scsi_qdev_realize;
+    k->unrealize = scsi_qdev_unrealize;
+    device_class_set_props(k, scsi_props);
+}
+
+static void scsi_dev_instance_init(Object *obj)
+{
+    DeviceState *dev = DEVICE(obj);
+    SCSIDevice *s = SCSI_DEVICE(dev);
+
+    device_add_bootindex_property(obj, &s->conf.bootindex,
+                                  "bootindex", NULL,
+                                  &s->qdev);
+}
+
+static const TypeInfo scsi_device_type_info = {
+    .name = TYPE_SCSI_DEVICE,
+    .parent = TYPE_DEVICE,
+    .instance_size = sizeof(SCSIDevice),
+    .abstract = true,
+    .class_size = sizeof(SCSIDeviceClass),
+    .class_init = scsi_device_class_init,
+    .instance_init = scsi_dev_instance_init,
+};
+
+static void scsi_bus_class_init(ObjectClass *klass, void *data)
+{
+    BusClass *k = BUS_CLASS(klass);
+    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(klass);
+
+    k->get_dev_path = scsibus_get_dev_path;
+    k->get_fw_dev_path = scsibus_get_fw_dev_path;
+    k->check_address = scsi_bus_check_address;
+    hc->unplug = qdev_simple_device_unplug_cb;
+}
+
+static const TypeInfo scsi_bus_info = {
+    .name = TYPE_SCSI_BUS,
+    .parent = TYPE_BUS,
+    .instance_size = sizeof(SCSIBus),
+    .class_init = scsi_bus_class_init,
+    .interfaces = (InterfaceInfo[]) {
+        { TYPE_HOTPLUG_HANDLER },
+        { }
+    }
+};
+
+static void scsi_register_types(void)
+{
+    type_register_static(&scsi_bus_info);
+    type_register_static(&scsi_device_type_info);
+}
+
+type_init(scsi_register_types)