Archipelago » qemu

/*

 * UAS (USB Attached SCSI) emulation

 *

 * Copyright Red Hat, Inc. 2012

 *

 * Author: Gerd Hoffmann <kraxel@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-common.h"

#include "qemu/option.h"

#include "qemu/config-file.h"

#include "trace.h"

#include "hw/usb.h"

#include "hw/usb/desc.h"

#include "hw/scsi/scsi.h"

#include "block/scsi.h"

/* --------------------------------------------------------------------- */

#define UAS_UI_COMMAND              0x01

#define UAS_UI_SENSE                0x03

#define UAS_UI_RESPONSE             0x04

#define UAS_UI_TASK_MGMT            0x05

#define UAS_UI_READ_READY           0x06

#define UAS_UI_WRITE_READY          0x07

#define UAS_RC_TMF_COMPLETE         0x00

#define UAS_RC_INVALID_INFO_UNIT    0x02

#define UAS_RC_TMF_NOT_SUPPORTED    0x04

#define UAS_RC_TMF_FAILED           0x05

#define UAS_RC_TMF_SUCCEEDED        0x08

#define UAS_RC_INCORRECT_LUN        0x09

#define UAS_RC_OVERLAPPED_TAG       0x0a

#define UAS_TMF_ABORT_TASK          0x01

#define UAS_TMF_ABORT_TASK_SET      0x02

#define UAS_TMF_CLEAR_TASK_SET      0x04

#define UAS_TMF_LOGICAL_UNIT_RESET  0x08

#define UAS_TMF_I_T_NEXUS_RESET     0x10

#define UAS_TMF_CLEAR_ACA           0x40

#define UAS_TMF_QUERY_TASK          0x80

#define UAS_TMF_QUERY_TASK_SET      0x81

#define UAS_TMF_QUERY_ASYNC_EVENT   0x82

#define UAS_PIPE_ID_COMMAND         0x01

#define UAS_PIPE_ID_STATUS          0x02

#define UAS_PIPE_ID_DATA_IN         0x03

#define UAS_PIPE_ID_DATA_OUT        0x04

typedef struct {

    uint8_t    id;

    uint8_t    reserved;

    uint16_t   tag;

} QEMU_PACKED  uas_ui_header;

typedef struct {

    uint8_t    prio_taskattr;   /* 6:3 priority, 2:0 task attribute   */

    uint8_t    reserved_1;

    uint8_t    add_cdb_length;  /* 7:2 additional adb length (dwords) */

    uint8_t    reserved_2;

    uint64_t   lun;

    uint8_t    cdb[16];

    uint8_t    add_cdb[];

} QEMU_PACKED  uas_ui_command;

typedef struct {

    uint16_t   status_qualifier;

    uint8_t    status;

    uint8_t    reserved[7];

    uint16_t   sense_length;

    uint8_t    sense_data[18];

} QEMU_PACKED  uas_ui_sense;

typedef struct {

    uint16_t   add_response_info;

    uint8_t    response_code;

} QEMU_PACKED  uas_ui_response;

typedef struct {

    uint8_t    function;

    uint8_t    reserved;

    uint16_t   task_tag;

    uint64_t   lun;

} QEMU_PACKED  uas_ui_task_mgmt;

typedef struct {

    uas_ui_header  hdr;

    union {

        uas_ui_command   command;

        uas_ui_sense     sense;

        uas_ui_task_mgmt task;

        uas_ui_response  response;

    };

} QEMU_PACKED  uas_ui;

/* --------------------------------------------------------------------- */

#define UAS_STREAM_BM_ATTR  4

#define UAS_MAX_STREAMS     (1 << UAS_STREAM_BM_ATTR)

typedef struct UASDevice UASDevice;

typedef struct UASRequest UASRequest;

typedef struct UASStatus UASStatus;

struct UASDevice {

    USBDevice                 dev;

    SCSIBus                   bus;

    QEMUBH                    *status_bh;

    QTAILQ_HEAD(, UASStatus)  results;

    QTAILQ_HEAD(, UASRequest) requests;

    /* usb 2.0 only */

    USBPacket                 *status2;

    UASRequest                *datain2;

    UASRequest                *dataout2;

    /* usb 3.0 only */

    USBPacket                 *data3[UAS_MAX_STREAMS];

    USBPacket                 *status3[UAS_MAX_STREAMS];

};

struct UASRequest {

    uint16_t     tag;

    uint64_t     lun;

    UASDevice    *uas;

    SCSIDevice   *dev;

    SCSIRequest  *req;

    USBPacket    *data;

    bool         data_async;

    bool         active;

    bool         complete;

    uint32_t     buf_off;

    uint32_t     buf_size;

    uint32_t     data_off;

    uint32_t     data_size;

    QTAILQ_ENTRY(UASRequest)  next;

};

struct UASStatus {

    uint32_t                  stream;

    uas_ui                    status;

    uint32_t                  length;

    QTAILQ_ENTRY(UASStatus)   next;

};

/* --------------------------------------------------------------------- */

enum {

    STR_MANUFACTURER = 1,

    STR_PRODUCT,

    STR_SERIALNUMBER,

    STR_CONFIG_HIGH,

    STR_CONFIG_SUPER,

};

static const USBDescStrings desc_strings = {

    [STR_MANUFACTURER] = "QEMU",

    [STR_PRODUCT]      = "USB Attached SCSI HBA",

    [STR_SERIALNUMBER] = "27842",

    [STR_CONFIG_HIGH]  = "High speed config (usb 2.0)",

    [STR_CONFIG_SUPER] = "Super speed config (usb 3.0)",

};

static const USBDescIface desc_iface_high = {

    .bInterfaceNumber              = 0,

    .bNumEndpoints                 = 4,

    .bInterfaceClass               = USB_CLASS_MASS_STORAGE,

    .bInterfaceSubClass            = 0x06, /* SCSI */

    .bInterfaceProtocol            = 0x62, /* UAS  */

    .eps = (USBDescEndpoint[]) {

        {

            .bEndpointAddress      = USB_DIR_OUT | UAS_PIPE_ID_COMMAND,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 512,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_COMMAND,

                0x00,  /*  u8  bReserved */

            },

        },{

            .bEndpointAddress      = USB_DIR_IN | UAS_PIPE_ID_STATUS,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 512,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_STATUS,

                0x00,  /*  u8  bReserved */

            },

        },{

            .bEndpointAddress      = USB_DIR_IN | UAS_PIPE_ID_DATA_IN,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 512,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_DATA_IN,

                0x00,  /*  u8  bReserved */

            },

        },{

            .bEndpointAddress      = USB_DIR_OUT | UAS_PIPE_ID_DATA_OUT,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 512,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_DATA_OUT,

                0x00,  /*  u8  bReserved */

            },

        },

    }

};

static const USBDescIface desc_iface_super = {

    .bInterfaceNumber              = 0,

    .bNumEndpoints                 = 4,

    .bInterfaceClass               = USB_CLASS_MASS_STORAGE,

    .bInterfaceSubClass            = 0x06, /* SCSI */

    .bInterfaceProtocol            = 0x62, /* UAS  */

    .eps = (USBDescEndpoint[]) {

        {

            .bEndpointAddress      = USB_DIR_OUT | UAS_PIPE_ID_COMMAND,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 1024,

            .bMaxBurst             = 15,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_COMMAND,

                0x00,  /*  u8  bReserved */

            },

        },{

            .bEndpointAddress      = USB_DIR_IN | UAS_PIPE_ID_STATUS,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 1024,

            .bMaxBurst             = 15,

            .bmAttributes_super    = UAS_STREAM_BM_ATTR,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_STATUS,

                0x00,  /*  u8  bReserved */

            },

        },{

            .bEndpointAddress      = USB_DIR_IN | UAS_PIPE_ID_DATA_IN,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 1024,

            .bMaxBurst             = 15,

            .bmAttributes_super    = UAS_STREAM_BM_ATTR,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_DATA_IN,

                0x00,  /*  u8  bReserved */

            },

        },{

            .bEndpointAddress      = USB_DIR_OUT | UAS_PIPE_ID_DATA_OUT,

            .bmAttributes          = USB_ENDPOINT_XFER_BULK,

            .wMaxPacketSize        = 1024,

            .bMaxBurst             = 15,

            .bmAttributes_super    = UAS_STREAM_BM_ATTR,

            .extra = (uint8_t[]) {

                0x04,  /*  u8  bLength */

                0x24,  /*  u8  bDescriptorType */

                UAS_PIPE_ID_DATA_OUT,

                0x00,  /*  u8  bReserved */

            },

        },

    }

};

static const USBDescDevice desc_device_high = {

    .bcdUSB                        = 0x0200,

    .bMaxPacketSize0               = 64,

    .bNumConfigurations            = 1,

    .confs = (USBDescConfig[]) {

        {

            .bNumInterfaces        = 1,

            .bConfigurationValue   = 1,

            .iConfiguration        = STR_CONFIG_HIGH,

            .bmAttributes          = 0xc0,

            .nif = 1,

            .ifs = &desc_iface_high,

        },

    },

};

static const USBDescDevice desc_device_super = {

    .bcdUSB                        = 0x0300,

    .bMaxPacketSize0               = 64,

    .bNumConfigurations            = 1,

    .confs = (USBDescConfig[]) {

        {

            .bNumInterfaces        = 1,

            .bConfigurationValue   = 1,

            .iConfiguration        = STR_CONFIG_SUPER,

            .bmAttributes          = 0xc0,

            .nif = 1,

            .ifs = &desc_iface_super,

        },

    },

};

static const USBDesc desc = {

    .id = {

        .idVendor          = 0x46f4, /* CRC16() of "QEMU" */

        .idProduct         = 0x0003,

        .bcdDevice         = 0,

        .iManufacturer     = STR_MANUFACTURER,

        .iProduct          = STR_PRODUCT,

        .iSerialNumber     = STR_SERIALNUMBER,

    },

    .high  = &desc_device_high,

    .super = &desc_device_super,

    .str   = desc_strings,

};

/* --------------------------------------------------------------------- */

static bool uas_using_streams(UASDevice *uas)

{

    return uas->dev.speed == USB_SPEED_SUPER;

}

/* --------------------------------------------------------------------- */

static UASStatus *usb_uas_alloc_status(UASDevice *uas, uint8_t id, uint16_t tag)

{

    UASStatus *st = g_new0(UASStatus, 1);

    st->status.hdr.id = id;

    st->status.hdr.tag = cpu_to_be16(tag);

    st->length = sizeof(uas_ui_header);

    if (uas_using_streams(uas)) {

        st->stream = tag;

    }

    return st;

}

static void usb_uas_send_status_bh(void *opaque)

{

    UASDevice *uas = opaque;

    UASStatus *st;

    USBPacket *p;

    while ((st = QTAILQ_FIRST(&uas->results)) != NULL) {

        if (uas_using_streams(uas)) {

            p = uas->status3[st->stream];

            uas->status3[st->stream] = NULL;

        } else {

            p = uas->status2;

            uas->status2 = NULL;

        }

        if (p == NULL) {

            break;

        }

        usb_packet_copy(p, &st->status, st->length);

        QTAILQ_REMOVE(&uas->results, st, next);

        g_free(st);

        p->status = USB_RET_SUCCESS; /* Clear previous ASYNC status */

        usb_packet_complete(&uas->dev, p);

    }

}

static void usb_uas_queue_status(UASDevice *uas, UASStatus *st, int length)

{

    USBPacket *p = uas_using_streams(uas) ?

        uas->status3[st->stream] : uas->status2;

    st->length += length;

    QTAILQ_INSERT_TAIL(&uas->results, st, next);

    if (p) {

        /*

         * Just schedule bh make sure any in-flight data transaction

         * is finished before completing (sending) the status packet.

         */

        qemu_bh_schedule(uas->status_bh);

    } else {

        USBEndpoint *ep = usb_ep_get(&uas->dev, USB_TOKEN_IN,

                                     UAS_PIPE_ID_STATUS);

        usb_wakeup(ep, st->stream);

    }

}

static void usb_uas_queue_response(UASDevice *uas, uint16_t tag,

                                   uint8_t code, uint16_t add_info)

{

    UASStatus *st = usb_uas_alloc_status(uas, UAS_UI_RESPONSE, tag);

    trace_usb_uas_response(uas->dev.addr, tag, code);

    st->status.response.response_code = code;

    st->status.response.add_response_info = cpu_to_be16(add_info);

    usb_uas_queue_status(uas, st, sizeof(uas_ui_response));

}

static void usb_uas_queue_sense(UASRequest *req, uint8_t status)

{

    UASStatus *st = usb_uas_alloc_status(req->uas, UAS_UI_SENSE, req->tag);

    int len, slen = 0;

    trace_usb_uas_sense(req->uas->dev.addr, req->tag, status);

    st->status.sense.status = status;

    st->status.sense.status_qualifier = cpu_to_be16(0);

    if (status != GOOD) {

        slen = scsi_req_get_sense(req->req, st->status.sense.sense_data,

                                  sizeof(st->status.sense.sense_data));

        st->status.sense.sense_length = cpu_to_be16(slen);

    }

    len = sizeof(uas_ui_sense) - sizeof(st->status.sense.sense_data) + slen;

    usb_uas_queue_status(req->uas, st, len);

}

static void usb_uas_queue_read_ready(UASRequest *req)

{

    UASStatus *st = usb_uas_alloc_status(req->uas, UAS_UI_READ_READY,

                                         req->tag);

    trace_usb_uas_read_ready(req->uas->dev.addr, req->tag);

    usb_uas_queue_status(req->uas, st, 0);

}

static void usb_uas_queue_write_ready(UASRequest *req)

{

    UASStatus *st = usb_uas_alloc_status(req->uas, UAS_UI_WRITE_READY,

                                         req->tag);

    trace_usb_uas_write_ready(req->uas->dev.addr, req->tag);

    usb_uas_queue_status(req->uas, st, 0);

}

/* --------------------------------------------------------------------- */

static int usb_uas_get_lun(uint64_t lun64)

{

    return (lun64 >> 48) & 0xff;

}

static SCSIDevice *usb_uas_get_dev(UASDevice *uas, uint64_t lun64)

{

    if ((lun64 >> 56) != 0x00) {

        return NULL;

    }

    return scsi_device_find(&uas->bus, 0, 0, usb_uas_get_lun(lun64));

}

static void usb_uas_complete_data_packet(UASRequest *req)

{

    USBPacket *p;

    if (!req->data_async) {

        return;

    }

    p = req->data;

    req->data = NULL;

    req->data_async = false;

    p->status = USB_RET_SUCCESS; /* Clear previous ASYNC status */

    usb_packet_complete(&req->uas->dev, p);

}

static void usb_uas_copy_data(UASRequest *req)

{

    uint32_t length;

    length = MIN(req->buf_size - req->buf_off,

                 req->data->iov.size - req->data->actual_length);

    trace_usb_uas_xfer_data(req->uas->dev.addr, req->tag, length,

                            req->data->actual_length, req->data->iov.size,

                            req->buf_off, req->buf_size);

    usb_packet_copy(req->data, scsi_req_get_buf(req->req) + req->buf_off,

                    length);

    req->buf_off += length;

    req->data_off += length;

    if (req->data->actual_length == req->data->iov.size) {

        usb_uas_complete_data_packet(req);

    }

    if (req->buf_size && req->buf_off == req->buf_size) {

        req->buf_off = 0;

        req->buf_size = 0;

        scsi_req_continue(req->req);

    }

}

static void usb_uas_start_next_transfer(UASDevice *uas)

{

    UASRequest *req;

    if (uas_using_streams(uas)) {

        return;

    }

    QTAILQ_FOREACH(req, &uas->requests, next) {

        if (req->active || req->complete) {

            continue;

        }

        if (req->req->cmd.mode == SCSI_XFER_FROM_DEV && uas->datain2 == NULL) {

            uas->datain2 = req;

            usb_uas_queue_read_ready(req);

            req->active = true;

            return;

        }

        if (req->req->cmd.mode == SCSI_XFER_TO_DEV && uas->dataout2 == NULL) {

            uas->dataout2 = req;

            usb_uas_queue_write_ready(req);

            req->active = true;

            return;

        }

    }

}

static UASRequest *usb_uas_alloc_request(UASDevice *uas, uas_ui *ui)

{

    UASRequest *req;

    req = g_new0(UASRequest, 1);

    req->uas = uas;

    req->tag = be16_to_cpu(ui->hdr.tag);

    req->lun = be64_to_cpu(ui->command.lun);

    req->dev = usb_uas_get_dev(req->uas, req->lun);

    return req;

}

static void usb_uas_scsi_free_request(SCSIBus *bus, void *priv)

{

    UASRequest *req = priv;

    UASDevice *uas = req->uas;

    if (req == uas->datain2) {

        uas->datain2 = NULL;

    }

    if (req == uas->dataout2) {

        uas->dataout2 = NULL;

    }

    QTAILQ_REMOVE(&uas->requests, req, next);

    g_free(req);

    usb_uas_start_next_transfer(uas);

}

static UASRequest *usb_uas_find_request(UASDevice *uas, uint16_t tag)

{

    UASRequest *req;

    QTAILQ_FOREACH(req, &uas->requests, next) {

        if (req->tag == tag) {

            return req;

        }

    }

    return NULL;

}

static void usb_uas_scsi_transfer_data(SCSIRequest *r, uint32_t len)

{

    UASRequest *req = r->hba_private;

    trace_usb_uas_scsi_data(req->uas->dev.addr, req->tag, len);

    req->buf_off = 0;

    req->buf_size = len;

    if (req->data) {

        usb_uas_copy_data(req);

    } else {

        usb_uas_start_next_transfer(req->uas);

    }

}

static void usb_uas_scsi_command_complete(SCSIRequest *r,

                                          uint32_t status, size_t resid)

{

    UASRequest *req = r->hba_private;

    trace_usb_uas_scsi_complete(req->uas->dev.addr, req->tag, status, resid);

    req->complete = true;

    if (req->data) {

        usb_uas_complete_data_packet(req);

    }

    usb_uas_queue_sense(req, status);

    scsi_req_unref(req->req);

}

static void usb_uas_scsi_request_cancelled(SCSIRequest *r)

{

    UASRequest *req = r->hba_private;

    /* FIXME: queue notification to status pipe? */

    scsi_req_unref(req->req);

}

static const struct SCSIBusInfo usb_uas_scsi_info = {

    .tcq = true,

    .max_target = 0,

    .max_lun = 255,

    .transfer_data = usb_uas_scsi_transfer_data,

    .complete = usb_uas_scsi_command_complete,

    .cancel = usb_uas_scsi_request_cancelled,

    .free_request = usb_uas_scsi_free_request,

};

/* --------------------------------------------------------------------- */

static void usb_uas_handle_reset(USBDevice *dev)

{

    UASDevice *uas = DO_UPCAST(UASDevice, dev, dev);

    UASRequest *req, *nreq;

    UASStatus *st, *nst;

    trace_usb_uas_reset(dev->addr);

    QTAILQ_FOREACH_SAFE(req, &uas->requests, next, nreq) {

        scsi_req_cancel(req->req);

    }

    QTAILQ_FOREACH_SAFE(st, &uas->results, next, nst) {

        QTAILQ_REMOVE(&uas->results, st, next);

        g_free(st);

    }

}

static void usb_uas_handle_control(USBDevice *dev, USBPacket *p,

               int request, int value, int index, int length, uint8_t *data)

{

    int ret;

    ret = usb_desc_handle_control(dev, p, request, value, index, length, data);

    if (ret >= 0) {

        return;

    }

    fprintf(stderr, "%s: unhandled control request\n", __func__);

    p->status = USB_RET_STALL;

}

static void usb_uas_cancel_io(USBDevice *dev, USBPacket *p)

{

    UASDevice *uas = DO_UPCAST(UASDevice, dev, dev);

    UASRequest *req, *nreq;

    int i;

    if (uas->status2 == p) {

        uas->status2 = NULL;

        qemu_bh_cancel(uas->status_bh);

        return;

    }

    if (uas_using_streams(uas)) {

        for (i = 0; i < UAS_MAX_STREAMS; i++) {

            if (uas->status3[i] == p) {

                uas->status3[i] = NULL;

                return;

            }

            if (uas->data3[i] == p) {

                uas->data3[i] = NULL;

                return;

            }

        }

    }

    QTAILQ_FOREACH_SAFE(req, &uas->requests, next, nreq) {

        if (req->data == p) {

            req->data = NULL;

            return;

        }

    }

    assert(!"canceled usb packet not found");

}

static void usb_uas_command(UASDevice *uas, uas_ui *ui)

{

    UASRequest *req;

    uint32_t len;

    req = usb_uas_find_request(uas, be16_to_cpu(ui->hdr.tag));

    if (req) {

        goto overlapped_tag;

    }

    req = usb_uas_alloc_request(uas, ui);

    if (req->dev == NULL) {

        goto bad_target;

    }

    trace_usb_uas_command(uas->dev.addr, req->tag,

                          usb_uas_get_lun(req->lun),

                          req->lun >> 32, req->lun & 0xffffffff);

    QTAILQ_INSERT_TAIL(&uas->requests, req, next);

    if (uas_using_streams(uas) && uas->data3[req->tag] != NULL) {

        req->data = uas->data3[req->tag];

        req->data_async = true;

        uas->data3[req->tag] = NULL;

    }

    req->req = scsi_req_new(req->dev, req->tag,

                            usb_uas_get_lun(req->lun),

                            ui->command.cdb, req);

#if 1

    scsi_req_print(req->req);

#endif

    len = scsi_req_enqueue(req->req);

    if (len) {

        req->data_size = len;

        scsi_req_continue(req->req);

    }

    return;

overlapped_tag:

    usb_uas_queue_response(uas, req->tag, UAS_RC_OVERLAPPED_TAG, 0);

    return;

bad_target:

    /*

     * FIXME: Seems to upset linux, is this wrong?

     * NOTE: Happens only with no scsi devices at the bus, not sure

     *       this is a valid UAS setup in the first place.

     */

    usb_uas_queue_response(uas, req->tag, UAS_RC_INVALID_INFO_UNIT, 0);

    g_free(req);

}

static void usb_uas_task(UASDevice *uas, uas_ui *ui)

{

    uint16_t tag = be16_to_cpu(ui->hdr.tag);

    uint64_t lun64 = be64_to_cpu(ui->task.lun);

    SCSIDevice *dev = usb_uas_get_dev(uas, lun64);

    int lun = usb_uas_get_lun(lun64);

    UASRequest *req;

    uint16_t task_tag;

    req = usb_uas_find_request(uas, be16_to_cpu(ui->hdr.tag));

    if (req) {

        goto overlapped_tag;

    }

    switch (ui->task.function) {

    case UAS_TMF_ABORT_TASK:

        task_tag = be16_to_cpu(ui->task.task_tag);

        trace_usb_uas_tmf_abort_task(uas->dev.addr, tag, task_tag);

        if (dev == NULL) {

            goto bad_target;

        }

        if (dev->lun != lun) {

            goto incorrect_lun;

        }

        req = usb_uas_find_request(uas, task_tag);

        if (req && req->dev == dev) {

            scsi_req_cancel(req->req);

        }

        usb_uas_queue_response(uas, tag, UAS_RC_TMF_COMPLETE, 0);

        break;

    case UAS_TMF_LOGICAL_UNIT_RESET:

        trace_usb_uas_tmf_logical_unit_reset(uas->dev.addr, tag, lun);

        if (dev == NULL) {

            goto bad_target;

        }

        if (dev->lun != lun) {

            goto incorrect_lun;

        }

        qdev_reset_all(&dev->qdev);

        usb_uas_queue_response(uas, tag, UAS_RC_TMF_COMPLETE, 0);

        break;

    default:

        trace_usb_uas_tmf_unsupported(uas->dev.addr, tag, ui->task.function);

        usb_uas_queue_response(uas, tag, UAS_RC_TMF_NOT_SUPPORTED, 0);

        break;

    }

    return;

overlapped_tag:

    usb_uas_queue_response(uas, req->tag, UAS_RC_OVERLAPPED_TAG, 0);

    return;

bad_target:

    /* FIXME: correct?  [see long comment in usb_uas_command()] */

    usb_uas_queue_response(uas, tag, UAS_RC_INVALID_INFO_UNIT, 0);

    return;

incorrect_lun:

    usb_uas_queue_response(uas, tag, UAS_RC_INCORRECT_LUN, 0);

}

static void usb_uas_handle_data(USBDevice *dev, USBPacket *p)

{

    UASDevice *uas = DO_UPCAST(UASDevice, dev, dev);

    uas_ui ui;

    UASStatus *st;

    UASRequest *req;

    int length;

    switch (p->ep->nr) {

    case UAS_PIPE_ID_COMMAND:

        length = MIN(sizeof(ui), p->iov.size);

        usb_packet_copy(p, &ui, length);

        switch (ui.hdr.id) {

        case UAS_UI_COMMAND:

            usb_uas_command(uas, &ui);

            break;

        case UAS_UI_TASK_MGMT:

            usb_uas_task(uas, &ui);

            break;

        default:

            fprintf(stderr, "%s: unknown command ui: id 0x%x\n",

                    __func__, ui.hdr.id);

            p->status = USB_RET_STALL;

            break;

        }

        break;

    case UAS_PIPE_ID_STATUS:

        if (p->stream) {

            QTAILQ_FOREACH(st, &uas->results, next) {

                if (st->stream == p->stream) {

                    break;

                }

            }

            if (st == NULL) {

                assert(uas->status3[p->stream] == NULL);

                uas->status3[p->stream] = p;

                p->status = USB_RET_ASYNC;

                break;

            }

        } else {

            st = QTAILQ_FIRST(&uas->results);

            if (st == NULL) {

                assert(uas->status2 == NULL);

                uas->status2 = p;

                p->status = USB_RET_ASYNC;

                break;

            }

        }

        usb_packet_copy(p, &st->status, st->length);

        QTAILQ_REMOVE(&uas->results, st, next);

        g_free(st);

        break;

    case UAS_PIPE_ID_DATA_IN:

    case UAS_PIPE_ID_DATA_OUT:

        if (p->stream) {

            req = usb_uas_find_request(uas, p->stream);

        } else {

            req = (p->ep->nr == UAS_PIPE_ID_DATA_IN)

                ? uas->datain2 : uas->dataout2;

        }

        if (req == NULL) {

            if (p->stream) {

                assert(uas->data3[p->stream] == NULL);

                uas->data3[p->stream] = p;

                p->status = USB_RET_ASYNC;

                break;

            } else {

                fprintf(stderr, "%s: no inflight request\n", __func__);

                p->status = USB_RET_STALL;

                break;

            }

        }

        scsi_req_ref(req->req);

        req->data = p;

        usb_uas_copy_data(req);

        if (p->actual_length == p->iov.size || req->complete) {

            req->data = NULL;

        } else {

            req->data_async = true;

            p->status = USB_RET_ASYNC;

        }

        scsi_req_unref(req->req);

        usb_uas_start_next_transfer(uas);

        break;

    default:

        fprintf(stderr, "%s: invalid endpoint %d\n", __func__, p->ep->nr);

        p->status = USB_RET_STALL;

        break;

    }

}

static void usb_uas_handle_destroy(USBDevice *dev)

{

    UASDevice *uas = DO_UPCAST(UASDevice, dev, dev);

    qemu_bh_delete(uas->status_bh);

}

static int usb_uas_init(USBDevice *dev)

{

    UASDevice *uas = DO_UPCAST(UASDevice, dev, dev);

    usb_desc_create_serial(dev);

    usb_desc_init(dev);

    QTAILQ_INIT(&uas->results);

    QTAILQ_INIT(&uas->requests);

    uas->status_bh = qemu_bh_new(usb_uas_send_status_bh, uas);

    scsi_bus_new(&uas->bus, &uas->dev.qdev, &usb_uas_scsi_info, NULL);

    return 0;

}

static const VMStateDescription vmstate_usb_uas = {

    .name = "usb-uas",

    .unmigratable = 1,

    .fields = (VMStateField[]) {

        VMSTATE_USB_DEVICE(dev, UASDevice),

        VMSTATE_END_OF_LIST()

    }

};

static void usb_uas_class_initfn(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    USBDeviceClass *uc = USB_DEVICE_CLASS(klass);

    uc->init           = usb_uas_init;

    uc->product_desc   = desc_strings[STR_PRODUCT];

    uc->usb_desc       = &desc;

    uc->cancel_packet  = usb_uas_cancel_io;

    uc->handle_attach  = usb_desc_attach;

    uc->handle_reset   = usb_uas_handle_reset;

    uc->handle_control = usb_uas_handle_control;

    uc->handle_data    = usb_uas_handle_data;

    uc->handle_destroy = usb_uas_handle_destroy;

    dc->fw_name = "storage";

    dc->vmsd = &vmstate_usb_uas;

}