Archipelago » qemu

/*

 * SCSI Device emulation

 *

 * Copyright (c) 2006 CodeSourcery.

 * Based on code by Fabrice Bellard

 *

 * Written by Paul Brook

 * Modifications:

 *  2009-Dec-12 Artyom Tarasenko : implemented stamdard inquiry for the case

 *                                 when the allocation length of CDB is smaller

 *                                 than 36.

 *  2009-Oct-13 Artyom Tarasenko : implemented the block descriptor in the

 *                                 MODE SENSE response.

 *

 * This code is licenced under the LGPL.

 *

 * Note that this file only handles the SCSI architecture model and device

 * commands.  Emulation of interface/link layer protocols is handled by

 * the host adapter emulator.

 */

//#define DEBUG_SCSI

#ifdef DEBUG_SCSI

#define DPRINTF(fmt, ...) \

do { printf("scsi-disk: " fmt , ## __VA_ARGS__); } while (0)

#else

#define DPRINTF(fmt, ...) do {} while(0)

#endif

#define BADF(fmt, ...) \

do { fprintf(stderr, "scsi-disk: " fmt , ## __VA_ARGS__); } while (0)

#include "qemu-common.h"

#include "qemu-error.h"

#include "scsi.h"

#include "scsi-defs.h"

#include "sysemu.h"

#include "blockdev.h"

#define SCSI_DMA_BUF_SIZE    131072

#define SCSI_MAX_INQUIRY_LEN 256

#define SCSI_REQ_STATUS_RETRY           0x01

#define SCSI_REQ_STATUS_RETRY_TYPE_MASK 0x06

#define SCSI_REQ_STATUS_RETRY_READ      0x00

#define SCSI_REQ_STATUS_RETRY_WRITE     0x02

#define SCSI_REQ_STATUS_RETRY_FLUSH     0x04

typedef struct SCSIDiskState SCSIDiskState;

typedef struct SCSIDiskReq {

    SCSIRequest req;

    /* Both sector and sector_count are in terms of qemu 512 byte blocks.  */

    uint64_t sector;

    uint32_t sector_count;

    struct iovec iov;

    QEMUIOVector qiov;

    uint32_t status;

} SCSIDiskReq;

typedef enum { SCSI_HD, SCSI_CD } SCSIDriveKind;

struct SCSIDiskState

{

    SCSIDevice qdev;

    BlockDriverState *bs;

    /* The qemu block layer uses a fixed 512 byte sector size.

       This is the number of 512 byte blocks in a single scsi sector.  */

    int cluster_size;

    uint32_t removable;

    uint64_t max_lba;

    QEMUBH *bh;

    char *version;

    char *serial;

    SCSISense sense;

    SCSIDriveKind drive_kind;

};

static int scsi_handle_rw_error(SCSIDiskReq *r, int error, int type);

static int scsi_disk_emulate_command(SCSIDiskReq *r, uint8_t *outbuf);

static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag,

        uint32_t lun)

{

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, d);

    SCSIRequest *req;

    SCSIDiskReq *r;

    req = scsi_req_alloc(sizeof(SCSIDiskReq), &s->qdev, tag, lun);

    r = DO_UPCAST(SCSIDiskReq, req, req);

    r->iov.iov_base = qemu_blockalign(s->bs, SCSI_DMA_BUF_SIZE);

    return req;

}

static void scsi_free_request(SCSIRequest *req)

{

    SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);

    qemu_vfree(r->iov.iov_base);

}

static void scsi_disk_clear_sense(SCSIDiskState *s)

{

    memset(&s->sense, 0, sizeof(s->sense));

}

static void scsi_req_set_status(SCSIDiskReq *r, int status, SCSISense sense)

{

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

    r->req.status = status;

    s->sense = sense;

}

/* Helper function for command completion.  */

static void scsi_command_complete(SCSIDiskReq *r, int status, SCSISense sense)

{

    DPRINTF("Command complete tag=0x%x status=%d sense=%d/%d/%d\n",

            r->req.tag, status, sense.key, sense.asc, sense.ascq);

    scsi_req_set_status(r, status, sense);

    scsi_req_complete(&r->req);

}

/* Cancel a pending data transfer.  */

static void scsi_cancel_io(SCSIRequest *req)

{

    SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);

    DPRINTF("Cancel tag=0x%x\n", req->tag);

    if (r->req.aiocb) {

        bdrv_aio_cancel(r->req.aiocb);

    }

    r->req.aiocb = NULL;

}

static void scsi_read_complete(void * opaque, int ret)

{

    SCSIDiskReq *r = (SCSIDiskReq *)opaque;

    int n;

    r->req.aiocb = NULL;

    if (ret) {

        if (scsi_handle_rw_error(r, -ret, SCSI_REQ_STATUS_RETRY_READ)) {

            return;

        }

    }

    DPRINTF("Data ready tag=0x%x len=%zd\n", r->req.tag, r->iov.iov_len);

    n = r->iov.iov_len / 512;

    r->sector += n;

    r->sector_count -= n;

    scsi_req_data(&r->req, r->iov.iov_len);

}

/* Read more data from scsi device into buffer.  */

static void scsi_read_data(SCSIRequest *req)

{

    SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

    uint32_t n;

    if (r->sector_count == (uint32_t)-1) {

        DPRINTF("Read buf_len=%zd\n", r->iov.iov_len);

        r->sector_count = 0;

        scsi_req_data(&r->req, r->iov.iov_len);

        return;

    }

    DPRINTF("Read sector_count=%d\n", r->sector_count);

    if (r->sector_count == 0) {

        scsi_command_complete(r, GOOD, SENSE_CODE(NO_SENSE));

        return;

    }

    /* No data transfer may already be in progress */

    assert(r->req.aiocb == NULL);

    if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {

        DPRINTF("Data transfer direction invalid\n");

        scsi_read_complete(r, -EINVAL);

        return;

    }

    n = r->sector_count;

    if (n > SCSI_DMA_BUF_SIZE / 512)

        n = SCSI_DMA_BUF_SIZE / 512;

    r->iov.iov_len = n * 512;

    qemu_iovec_init_external(&r->qiov, &r->iov, 1);

    r->req.aiocb = bdrv_aio_readv(s->bs, r->sector, &r->qiov, n,

                              scsi_read_complete, r);

    if (r->req.aiocb == NULL) {

        scsi_read_complete(r, -EIO);

    }

}

static int scsi_handle_rw_error(SCSIDiskReq *r, int error, int type)

{

    int is_read = (type == SCSI_REQ_STATUS_RETRY_READ);

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

    BlockErrorAction action = bdrv_get_on_error(s->bs, is_read);

    if (action == BLOCK_ERR_IGNORE) {

        bdrv_mon_event(s->bs, BDRV_ACTION_IGNORE, is_read);

        return 0;

    }

    if ((error == ENOSPC && action == BLOCK_ERR_STOP_ENOSPC)

            || action == BLOCK_ERR_STOP_ANY) {

        type &= SCSI_REQ_STATUS_RETRY_TYPE_MASK;

        r->status |= SCSI_REQ_STATUS_RETRY | type;

        bdrv_mon_event(s->bs, BDRV_ACTION_STOP, is_read);

        vm_stop(VMSTOP_DISKFULL);

    } else {

        if (type == SCSI_REQ_STATUS_RETRY_READ) {

            scsi_req_data(&r->req, 0);

        }

        switch (error) {

        case ENOMEM:

            scsi_command_complete(r, CHECK_CONDITION,

                                  SENSE_CODE(TARGET_FAILURE));

            break;

        case EINVAL:

            scsi_command_complete(r, CHECK_CONDITION,

                                  SENSE_CODE(INVALID_FIELD));

            break;

        default:

            scsi_command_complete(r, CHECK_CONDITION,

                                  SENSE_CODE(IO_ERROR));

            break;

        }

        bdrv_mon_event(s->bs, BDRV_ACTION_REPORT, is_read);

    }

    return 1;

}

static void scsi_write_complete(void * opaque, int ret)

{

    SCSIDiskReq *r = (SCSIDiskReq *)opaque;

    uint32_t len;

    uint32_t n;

    r->req.aiocb = NULL;

    if (ret) {

        if (scsi_handle_rw_error(r, -ret, SCSI_REQ_STATUS_RETRY_WRITE)) {

            return;

        }

    }

    n = r->iov.iov_len / 512;

    r->sector += n;

    r->sector_count -= n;

    if (r->sector_count == 0) {

        scsi_command_complete(r, GOOD, SENSE_CODE(NO_SENSE));

    } else {

        len = r->sector_count * 512;

        if (len > SCSI_DMA_BUF_SIZE) {

            len = SCSI_DMA_BUF_SIZE;

        }

        r->iov.iov_len = len;

        DPRINTF("Write complete tag=0x%x more=%d\n", r->req.tag, len);

        scsi_req_data(&r->req, len);

    }

}

static void scsi_write_data(SCSIRequest *req)

{

    SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

    uint32_t n;

    /* No data transfer may already be in progress */

    assert(r->req.aiocb == NULL);

    if (r->req.cmd.mode != SCSI_XFER_TO_DEV) {

        DPRINTF("Data transfer direction invalid\n");

        scsi_write_complete(r, -EINVAL);

        return;

    }

    n = r->iov.iov_len / 512;

    if (n) {

        qemu_iovec_init_external(&r->qiov, &r->iov, 1);

        r->req.aiocb = bdrv_aio_writev(s->bs, r->sector, &r->qiov, n,

                                   scsi_write_complete, r);

        if (r->req.aiocb == NULL) {

            scsi_write_complete(r, -ENOMEM);

        }

    } else {

        /* Invoke completion routine to fetch data from host.  */

        scsi_write_complete(r, 0);

    }

}

static void scsi_dma_restart_bh(void *opaque)

{

    SCSIDiskState *s = opaque;

    SCSIRequest *req;

    SCSIDiskReq *r;

    qemu_bh_delete(s->bh);

    s->bh = NULL;

    QTAILQ_FOREACH(req, &s->qdev.requests, next) {

        r = DO_UPCAST(SCSIDiskReq, req, req);

        if (r->status & SCSI_REQ_STATUS_RETRY) {

            int status = r->status;

            int ret;

            r->status &=

                ~(SCSI_REQ_STATUS_RETRY | SCSI_REQ_STATUS_RETRY_TYPE_MASK);

            switch (status & SCSI_REQ_STATUS_RETRY_TYPE_MASK) {

            case SCSI_REQ_STATUS_RETRY_READ:

                scsi_read_data(&r->req);

                break;

            case SCSI_REQ_STATUS_RETRY_WRITE:

                scsi_write_data(&r->req);

                break;

            case SCSI_REQ_STATUS_RETRY_FLUSH:

                ret = scsi_disk_emulate_command(r, r->iov.iov_base);

                if (ret == 0) {

                    scsi_command_complete(r, GOOD, SENSE_CODE(NO_SENSE));

                }

            }

        }

    }

}

static void scsi_dma_restart_cb(void *opaque, int running, int reason)

{

    SCSIDiskState *s = opaque;

    if (!running)

        return;

    if (!s->bh) {

        s->bh = qemu_bh_new(scsi_dma_restart_bh, s);

        qemu_bh_schedule(s->bh);

    }

}

/* Return a pointer to the data buffer.  */

static uint8_t *scsi_get_buf(SCSIRequest *req)

{

    SCSIDiskReq *r = DO_UPCAST(SCSIDiskReq, req, req);

    return (uint8_t *)r->iov.iov_base;

}

/* Copy sense information into the provided buffer */

static int scsi_get_sense(SCSIRequest *req, uint8_t *outbuf, int len)

{

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, req->dev);

    return scsi_build_sense(s->sense, outbuf, len, len > 14);

}

static int scsi_disk_emulate_inquiry(SCSIRequest *req, uint8_t *outbuf)

{

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, req->dev);

    int buflen = 0;

    if (req->cmd.buf[1] & 0x2) {

        /* Command support data - optional, not implemented */

        BADF("optional INQUIRY command support request not implemented\n");

        return -1;

    }

    if (req->cmd.buf[1] & 0x1) {

        /* Vital product data */

        uint8_t page_code = req->cmd.buf[2];

        if (req->cmd.xfer < 4) {

            BADF("Error: Inquiry (EVPD[%02X]) buffer size %zd is "

                 "less than 4\n", page_code, req->cmd.xfer);

            return -1;

        }

        if (s->drive_kind == SCSI_CD) {

            outbuf[buflen++] = 5;

        } else {

            outbuf[buflen++] = 0;

        }

        outbuf[buflen++] = page_code ; // this page

        outbuf[buflen++] = 0x00;

        switch (page_code) {

        case 0x00: /* Supported page codes, mandatory */

        {

            int pages;

            DPRINTF("Inquiry EVPD[Supported pages] "

                    "buffer size %zd\n", req->cmd.xfer);

            pages = buflen++;

            outbuf[buflen++] = 0x00; // list of supported pages (this page)

            outbuf[buflen++] = 0x80; // unit serial number

            outbuf[buflen++] = 0x83; // device identification

            if (s->drive_kind == SCSI_HD) {

                outbuf[buflen++] = 0xb0; // block limits

                outbuf[buflen++] = 0xb2; // thin provisioning

            }

            outbuf[pages] = buflen - pages - 1; // number of pages

            break;

        }

        case 0x80: /* Device serial number, optional */

        {

            int l = strlen(s->serial);

            if (l > req->cmd.xfer)

                l = req->cmd.xfer;

            if (l > 20)

                l = 20;

            DPRINTF("Inquiry EVPD[Serial number] "

                    "buffer size %zd\n", req->cmd.xfer);

            outbuf[buflen++] = l;

            memcpy(outbuf+buflen, s->serial, l);

            buflen += l;

            break;

        }

        case 0x83: /* Device identification page, mandatory */

        {

            int max_len = 255 - 8;

            int id_len = strlen(bdrv_get_device_name(s->bs));

            if (id_len > max_len)

                id_len = max_len;

            DPRINTF("Inquiry EVPD[Device identification] "

                    "buffer size %zd\n", req->cmd.xfer);

            outbuf[buflen++] = 4 + id_len;

            outbuf[buflen++] = 0x2; // ASCII

            outbuf[buflen++] = 0;   // not officially assigned

            outbuf[buflen++] = 0;   // reserved

            outbuf[buflen++] = id_len; // length of data following

            memcpy(outbuf+buflen, bdrv_get_device_name(s->bs), id_len);

            buflen += id_len;

            break;

        }

        case 0xb0: /* block limits */

        {

            unsigned int unmap_sectors =

                    s->qdev.conf.discard_granularity / s->qdev.blocksize;

            unsigned int min_io_size =

                    s->qdev.conf.min_io_size / s->qdev.blocksize;

            unsigned int opt_io_size =

                    s->qdev.conf.opt_io_size / s->qdev.blocksize;

            if (s->drive_kind == SCSI_CD) {

                DPRINTF("Inquiry (EVPD[%02X] not supported for CDROM\n",

                        page_code);

                return -1;

            }

            /* required VPD size with unmap support */

            outbuf[3] = buflen = 0x3c;

            memset(outbuf + 4, 0, buflen - 4);

            /* optimal transfer length granularity */

            outbuf[6] = (min_io_size >> 8) & 0xff;

            outbuf[7] = min_io_size & 0xff;

            /* optimal transfer length */

            outbuf[12] = (opt_io_size >> 24) & 0xff;

            outbuf[13] = (opt_io_size >> 16) & 0xff;

            outbuf[14] = (opt_io_size >> 8) & 0xff;

            outbuf[15] = opt_io_size & 0xff;

            /* optimal unmap granularity */

            outbuf[28] = (unmap_sectors >> 24) & 0xff;

            outbuf[29] = (unmap_sectors >> 16) & 0xff;

            outbuf[30] = (unmap_sectors >> 8) & 0xff;

            outbuf[31] = unmap_sectors & 0xff;

            break;

        }

        case 0xb2: /* thin provisioning */

        {

            outbuf[3] = buflen = 8;

            outbuf[4] = 0;

            outbuf[5] = 0x40; /* write same with unmap supported */

            outbuf[6] = 0;

            outbuf[7] = 0;

            break;

        }

        default:

            BADF("Error: unsupported Inquiry (EVPD[%02X]) "

                 "buffer size %zd\n", page_code, req->cmd.xfer);

            return -1;

        }

        /* done with EVPD */

        return buflen;

    }

    /* Standard INQUIRY data */

    if (req->cmd.buf[2] != 0) {

        BADF("Error: Inquiry (STANDARD) page or code "

             "is non-zero [%02X]\n", req->cmd.buf[2]);

        return -1;

    }

    /* PAGE CODE == 0 */

    if (req->cmd.xfer < 5) {

        BADF("Error: Inquiry (STANDARD) buffer size %zd "

             "is less than 5\n", req->cmd.xfer);

        return -1;

    }

    buflen = req->cmd.xfer;

    if (buflen > SCSI_MAX_INQUIRY_LEN)

        buflen = SCSI_MAX_INQUIRY_LEN;

    memset(outbuf, 0, buflen);

    if (req->lun) {

        outbuf[0] = 0x7f;        /* LUN not supported */

        return buflen;

    }

    if (s->drive_kind == SCSI_CD) {

        outbuf[0] = 5;

        outbuf[1] = 0x80;

        memcpy(&outbuf[16], "QEMU CD-ROM     ", 16);

    } else {

        outbuf[0] = 0;

        outbuf[1] = s->removable ? 0x80 : 0;

        memcpy(&outbuf[16], "QEMU HARDDISK   ", 16);

    }

    memcpy(&outbuf[8], "QEMU    ", 8);

    memset(&outbuf[32], 0, 4);

    memcpy(&outbuf[32], s->version, MIN(4, strlen(s->version)));

    /*

     * We claim conformance to SPC-3, which is required for guests

     * to ask for modern features like READ CAPACITY(16) or the

     * block characteristics VPD page by default.  Not all of SPC-3

     * is actually implemented, but we're good enough.

     */

    outbuf[2] = 5;

    outbuf[3] = 2; /* Format 2 */

    if (buflen > 36) {

        outbuf[4] = buflen - 5; /* Additional Length = (Len - 1) - 4 */

    } else {

        /* If the allocation length of CDB is too small,

               the additional length is not adjusted */

        outbuf[4] = 36 - 5;

    }

    /* Sync data transfer and TCQ.  */

    outbuf[7] = 0x10 | (req->bus->tcq ? 0x02 : 0);

    return buflen;

}

static int mode_sense_page(SCSIRequest *req, int page, uint8_t *p,

                           int page_control)

{

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, req->dev);

    BlockDriverState *bdrv = s->bs;

    int cylinders, heads, secs;

    /*

     * If Changeable Values are requested, a mask denoting those mode parameters

     * that are changeable shall be returned. As we currently don't support

     * parameter changes via MODE_SELECT all bits are returned set to zero.

     * The buffer was already menset to zero by the caller of this function.

     */

    switch (page) {

    case 4: /* Rigid disk device geometry page. */

        p[0] = 4;

        p[1] = 0x16;

        if (page_control == 1) { /* Changeable Values */

            return p[1] + 2;

        }

        /* if a geometry hint is available, use it */

        bdrv_get_geometry_hint(bdrv, &cylinders, &heads, &secs);

        p[2] = (cylinders >> 16) & 0xff;

        p[3] = (cylinders >> 8) & 0xff;

        p[4] = cylinders & 0xff;

        p[5] = heads & 0xff;

        /* Write precomp start cylinder, disabled */

        p[6] = (cylinders >> 16) & 0xff;

        p[7] = (cylinders >> 8) & 0xff;

        p[8] = cylinders & 0xff;

        /* Reduced current start cylinder, disabled */

        p[9] = (cylinders >> 16) & 0xff;

        p[10] = (cylinders >> 8) & 0xff;

        p[11] = cylinders & 0xff;

        /* Device step rate [ns], 200ns */

        p[12] = 0;

        p[13] = 200;

        /* Landing zone cylinder */

        p[14] = 0xff;

        p[15] =  0xff;

        p[16] = 0xff;

        /* Medium rotation rate [rpm], 5400 rpm */

        p[20] = (5400 >> 8) & 0xff;

        p[21] = 5400 & 0xff;

        return p[1] + 2;

    case 5: /* Flexible disk device geometry page. */

        p[0] = 5;

        p[1] = 0x1e;

        if (page_control == 1) { /* Changeable Values */

            return p[1] + 2;

        }

        /* Transfer rate [kbit/s], 5Mbit/s */

        p[2] = 5000 >> 8;

        p[3] = 5000 & 0xff;

        /* if a geometry hint is available, use it */

        bdrv_get_geometry_hint(bdrv, &cylinders, &heads, &secs);

        p[4] = heads & 0xff;

        p[5] = secs & 0xff;

        p[6] = s->cluster_size * 2;

        p[8] = (cylinders >> 8) & 0xff;

        p[9] = cylinders & 0xff;

        /* Write precomp start cylinder, disabled */

        p[10] = (cylinders >> 8) & 0xff;

        p[11] = cylinders & 0xff;

        /* Reduced current start cylinder, disabled */

        p[12] = (cylinders >> 8) & 0xff;

        p[13] = cylinders & 0xff;

        /* Device step rate [100us], 100us */

        p[14] = 0;

        p[15] = 1;

        /* Device step pulse width [us], 1us */

        p[16] = 1;

        /* Device head settle delay [100us], 100us */

        p[17] = 0;

        p[18] = 1;

        /* Motor on delay [0.1s], 0.1s */

        p[19] = 1;

        /* Motor off delay [0.1s], 0.1s */

        p[20] = 1;

        /* Medium rotation rate [rpm], 5400 rpm */

        p[28] = (5400 >> 8) & 0xff;

        p[29] = 5400 & 0xff;

        return p[1] + 2;

    case 8: /* Caching page.  */

        p[0] = 8;

        p[1] = 0x12;

        if (page_control == 1) { /* Changeable Values */

            return p[1] + 2;

        }

        if (bdrv_enable_write_cache(s->bs)) {

            p[2] = 4; /* WCE */

        }

        return p[1] + 2;

    case 0x2a: /* CD Capabilities and Mechanical Status page. */

        if (s->drive_kind != SCSI_CD)

            return 0;

        p[0] = 0x2a;

        p[1] = 0x14;

        if (page_control == 1) { /* Changeable Values */

            return p[1] + 2;

        }

        p[2] = 3; // CD-R & CD-RW read

        p[3] = 0; // Writing not supported

        p[4] = 0x7f; /* Audio, composite, digital out,

                        mode 2 form 1&2, multi session */

        p[5] = 0xff; /* CD DA, DA accurate, RW supported,

                        RW corrected, C2 errors, ISRC,

                        UPC, Bar code */

        p[6] = 0x2d | (bdrv_is_locked(s->bs)? 2 : 0);

        /* Locking supported, jumper present, eject, tray */

        p[7] = 0; /* no volume & mute control, no

                     changer */

        p[8] = (50 * 176) >> 8; // 50x read speed

        p[9] = (50 * 176) & 0xff;

        p[10] = 0 >> 8; // No volume

        p[11] = 0 & 0xff;

        p[12] = 2048 >> 8; // 2M buffer

        p[13] = 2048 & 0xff;

        p[14] = (16 * 176) >> 8; // 16x read speed current

        p[15] = (16 * 176) & 0xff;

        p[18] = (16 * 176) >> 8; // 16x write speed

        p[19] = (16 * 176) & 0xff;

        p[20] = (16 * 176) >> 8; // 16x write speed current

        p[21] = (16 * 176) & 0xff;

        return p[1] + 2;

    default:

        return 0;

    }

}

static int scsi_disk_emulate_mode_sense(SCSIRequest *req, uint8_t *outbuf)

{

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, req->dev);

    uint64_t nb_sectors;

    int page, dbd, buflen, page_control;

    uint8_t *p;

    uint8_t dev_specific_param;

    dbd = req->cmd.buf[1]  & 0x8;

    page = req->cmd.buf[2] & 0x3f;

    page_control = (req->cmd.buf[2] & 0xc0) >> 6;

    DPRINTF("Mode Sense(%d) (page %d, xfer %zd, page_control %d)\n",

        (req->cmd.buf[0] == MODE_SENSE) ? 6 : 10, page, req->cmd.xfer, page_control);

    memset(outbuf, 0, req->cmd.xfer);

    p = outbuf;

    if (bdrv_is_read_only(s->bs)) {

        dev_specific_param = 0x80; /* Readonly.  */

    } else {

        dev_specific_param = 0x00;

    }

    if (req->cmd.buf[0] == MODE_SENSE) {

        p[1] = 0; /* Default media type.  */

        p[2] = dev_specific_param;

        p[3] = 0; /* Block descriptor length.  */

        p += 4;

    } else { /* MODE_SENSE_10 */

        p[2] = 0; /* Default media type.  */

        p[3] = dev_specific_param;

        p[6] = p[7] = 0; /* Block descriptor length.  */

        p += 8;

    }

    bdrv_get_geometry(s->bs, &nb_sectors);

    if (!dbd && nb_sectors) {

        if (req->cmd.buf[0] == MODE_SENSE) {

            outbuf[3] = 8; /* Block descriptor length  */

        } else { /* MODE_SENSE_10 */

            outbuf[7] = 8; /* Block descriptor length  */

        }

        nb_sectors /= s->cluster_size;

        if (nb_sectors > 0xffffff)

            nb_sectors = 0;

        p[0] = 0; /* media density code */

        p[1] = (nb_sectors >> 16) & 0xff;

        p[2] = (nb_sectors >> 8) & 0xff;

        p[3] = nb_sectors & 0xff;

        p[4] = 0; /* reserved */

        p[5] = 0; /* bytes 5-7 are the sector size in bytes */

        p[6] = s->cluster_size * 2;

        p[7] = 0;

        p += 8;

    }

    if (page_control == 3) { /* Saved Values */

        return -1; /* ILLEGAL_REQUEST */

    }

    switch (page) {

    case 0x04:

    case 0x05:

    case 0x08:

    case 0x2a:

        p += mode_sense_page(req, page, p, page_control);

        break;

    case 0x3f:

        p += mode_sense_page(req, 0x08, p, page_control);

        p += mode_sense_page(req, 0x2a, p, page_control);

        break;

    default:

        return -1; /* ILLEGAL_REQUEST */

    }

    buflen = p - outbuf;

    /*

     * The mode data length field specifies the length in bytes of the

     * following data that is available to be transferred. The mode data

     * length does not include itself.

     */

    if (req->cmd.buf[0] == MODE_SENSE) {

        outbuf[0] = buflen - 1;

    } else { /* MODE_SENSE_10 */

        outbuf[0] = ((buflen - 2) >> 8) & 0xff;

        outbuf[1] = (buflen - 2) & 0xff;

    }

    if (buflen > req->cmd.xfer)

        buflen = req->cmd.xfer;

    return buflen;

}

static int scsi_disk_emulate_read_toc(SCSIRequest *req, uint8_t *outbuf)

{

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, req->dev);

    int start_track, format, msf, toclen;

    uint64_t nb_sectors;

    msf = req->cmd.buf[1] & 2;

    format = req->cmd.buf[2] & 0xf;

    start_track = req->cmd.buf[6];

    bdrv_get_geometry(s->bs, &nb_sectors);

    DPRINTF("Read TOC (track %d format %d msf %d)\n", start_track, format, msf >> 1);

    nb_sectors /= s->cluster_size;

    switch (format) {

    case 0:

        toclen = cdrom_read_toc(nb_sectors, outbuf, msf, start_track);

        break;

    case 1:

        /* multi session : only a single session defined */

        toclen = 12;

        memset(outbuf, 0, 12);

        outbuf[1] = 0x0a;

        outbuf[2] = 0x01;

        outbuf[3] = 0x01;

        break;

    case 2:

        toclen = cdrom_read_toc_raw(nb_sectors, outbuf, msf, start_track);

        break;

    default:

        return -1;

    }

    if (toclen > req->cmd.xfer)

        toclen = req->cmd.xfer;

    return toclen;

}

static int scsi_disk_emulate_command(SCSIDiskReq *r, uint8_t *outbuf)

{

    SCSIRequest *req = &r->req;

    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, req->dev);

    uint64_t nb_sectors;

    int buflen = 0;

    int ret;

    switch (req->cmd.buf[0]) {

    case TEST_UNIT_READY:

        if (!bdrv_is_inserted(s->bs))

            goto not_ready;

        break;

    case REQUEST_SENSE:

        if (req->cmd.xfer < 4)

            goto illegal_request;

        buflen = scsi_build_sense(s->sense, outbuf, req->cmd.xfer,

                                  req->cmd.xfer > 13);

        scsi_disk_clear_sense(s);

        break;

    case INQUIRY:

        buflen = scsi_disk_emulate_inquiry(req, outbuf);

        if (buflen < 0)

            goto illegal_request;

        break;

    case MODE_SENSE:

    case MODE_SENSE_10:

        buflen = scsi_disk_emulate_mode_sense(req, outbuf);

        if (buflen < 0)

            goto illegal_request;

        break;

    case READ_TOC:

        buflen = scsi_disk_emulate_read_toc(req, outbuf);

        if (buflen < 0)

            goto illegal_request;

        break;

    case RESERVE:

        if (req->cmd.buf[1] & 1)

            goto illegal_request;

        break;

    case RESERVE_10:

        if (req->cmd.buf[1] & 3)