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 licensed 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"

#include "block_int.h"

#ifdef __linux

#include <scsi/sg.h>

#endif

#define SCSI_DMA_BUF_SIZE    131072

#define SCSI_MAX_INQUIRY_LEN 256

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;

    uint32_t buflen;

    struct iovec iov;

    QEMUIOVector qiov;

    BlockAcctCookie acct;

} SCSIDiskReq;

struct SCSIDiskState

{

    SCSIDevice qdev;

    uint32_t removable;

    bool media_changed;

    bool media_event;

    bool eject_request;

    QEMUBH *bh;

    char *version;

    char *serial;

    bool tray_open;

    bool tray_locked;

};

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

static void scsi_free_request(SCSIRequest *req)

{

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

    if (r->iov.iov_base) {

        qemu_vfree(r->iov.iov_base);

    }

}

/* Helper function for command completion with sense.  */

static void scsi_check_condition(SCSIDiskReq *r, SCSISense sense)

{

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

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

    scsi_req_build_sense(&r->req, sense);

    scsi_req_complete(&r->req, CHECK_CONDITION);

}

/* 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);

        /* This reference was left in by scsi_*_data.  We take ownership of

         * it the moment scsi_req_cancel is called, independent of whether

         * bdrv_aio_cancel completes the request or not.  */

        scsi_req_unref(&r->req);

    }

    r->req.aiocb = NULL;

}

static uint32_t scsi_init_iovec(SCSIDiskReq *r)

{

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

    if (!r->iov.iov_base) {

        r->buflen = SCSI_DMA_BUF_SIZE;

        r->iov.iov_base = qemu_blockalign(s->qdev.conf.bs, r->buflen);

    }

    r->iov.iov_len = MIN(r->sector_count * 512, r->buflen);

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

    return r->qiov.size / 512;

}

static void scsi_read_complete(void * opaque, int ret)

{

    SCSIDiskReq *r = (SCSIDiskReq *)opaque;

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

    int n;

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

        r->req.aiocb = NULL;

        bdrv_acct_done(s->qdev.conf.bs, &r->acct);

    }

    if (ret) {

        if (scsi_handle_rw_error(r, -ret)) {

            goto done;

        }

    }

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

    n = r->qiov.size / 512;

    r->sector += n;

    r->sector_count -= n;

    scsi_req_data(&r->req, r->qiov.size);

done:

    if (!r->req.io_canceled) {

        scsi_req_unref(&r->req);

    }

}

static void scsi_flush_complete(void * opaque, int ret)

{

    SCSIDiskReq *r = (SCSIDiskReq *)opaque;

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

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

        r->req.aiocb = NULL;

        bdrv_acct_done(s->qdev.conf.bs, &r->acct);

    }

    if (ret < 0) {

        if (scsi_handle_rw_error(r, -ret)) {

            goto done;

        }

    }

    scsi_req_complete(&r->req, GOOD);

done:

    if (!r->req.io_canceled) {

        scsi_req_unref(&r->req);

    }

}

/* 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) {

        /* This also clears the sense buffer for REQUEST SENSE.  */

        scsi_req_complete(&r->req, GOOD);

        return;

    }

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

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

    /* The request is used as the AIO opaque value, so add a ref.  */

    scsi_req_ref(&r->req);

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

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

        scsi_read_complete(r, -EINVAL);

        return;

    }

    if (s->tray_open) {

        scsi_read_complete(r, -ENOMEDIUM);

        return;

    }

    n = scsi_init_iovec(r);

    bdrv_acct_start(s->qdev.conf.bs, &r->acct, n * BDRV_SECTOR_SIZE, BDRV_ACCT_READ);

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

                              scsi_read_complete, r);

}

/*

 * scsi_handle_rw_error has two return values.  0 means that the error

 * must be ignored, 1 means that the error has been processed and the

 * caller should not do anything else for this request.  Note that

 * scsi_handle_rw_error always manages its reference counts, independent

 * of the return value.

 */

static int scsi_handle_rw_error(SCSIDiskReq *r, int error)

{

    int is_read = (r->req.cmd.xfer == SCSI_XFER_FROM_DEV);

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

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

    if (action == BLOCK_ERR_IGNORE) {

        bdrv_mon_event(s->qdev.conf.bs, BDRV_ACTION_IGNORE, is_read);

        return 0;

    }

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

            || action == BLOCK_ERR_STOP_ANY) {

        bdrv_mon_event(s->qdev.conf.bs, BDRV_ACTION_STOP, is_read);

        vm_stop(RUN_STATE_IO_ERROR);

        bdrv_iostatus_set_err(s->qdev.conf.bs, error);

        scsi_req_retry(&r->req);

    } else {

        switch (error) {

        case ENOMEDIUM:

            scsi_check_condition(r, SENSE_CODE(NO_MEDIUM));

            break;

        case ENOMEM:

            scsi_check_condition(r, SENSE_CODE(TARGET_FAILURE));

            break;

        case EINVAL:

            scsi_check_condition(r, SENSE_CODE(INVALID_FIELD));

            break;

        default:

            scsi_check_condition(r, SENSE_CODE(IO_ERROR));

            break;

        }

        bdrv_mon_event(s->qdev.conf.bs, BDRV_ACTION_REPORT, is_read);

    }

    return 1;

}

static void scsi_write_complete(void * opaque, int ret)

{

    SCSIDiskReq *r = (SCSIDiskReq *)opaque;

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

    uint32_t n;

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

        r->req.aiocb = NULL;

        bdrv_acct_done(s->qdev.conf.bs, &r->acct);

    }

    if (ret) {

        if (scsi_handle_rw_error(r, -ret)) {

            goto done;

        }

    }

    n = r->qiov.size / 512;

    r->sector += n;

    r->sector_count -= n;

    if (r->sector_count == 0) {

        scsi_req_complete(&r->req, GOOD);

    } else {

        scsi_init_iovec(r);

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

        scsi_req_data(&r->req, r->qiov.size);

    }

done:

    if (!r->req.io_canceled) {

        scsi_req_unref(&r->req);

    }

}

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);

    /* The request is used as the AIO opaque value, so add a ref.  */

    scsi_req_ref(&r->req);

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

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

        scsi_write_complete(r, -EINVAL);

        return;

    }

    n = r->qiov.size / 512;

    if (n) {

        if (s->tray_open) {

            scsi_write_complete(r, -ENOMEDIUM);

            return;

        }

        bdrv_acct_start(s->qdev.conf.bs, &r->acct, n * BDRV_SECTOR_SIZE, BDRV_ACCT_WRITE);

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

                                       scsi_write_complete, r);

    } else {

        /* Called for the first time.  Ask the driver to send us more data.  */

        scsi_write_complete(r, 0);

    }

}

/* 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;

}

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;

        }

        outbuf[buflen++] = s->qdev.type & 0x1f;

        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)

            if (s->serial) {

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

            }

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

            if (s->qdev.type == TYPE_DISK) {

                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;

            if (!s->serial) {

                DPRINTF("Inquiry (EVPD[Serial number] not supported\n");

                return -1;

            }

            l = strlen(s->serial);

            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->qdev.conf.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->qdev.conf.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->qdev.type == TYPE_ROM) {

                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);

    outbuf[0] = s->qdev.type & 0x1f;

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

    if (s->qdev.type == TYPE_ROM) {

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

    } else {

        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->info->tcq ? 0x02 : 0);

    return buflen;

}

static inline bool media_is_dvd(SCSIDiskState *s)

{

    uint64_t nb_sectors;

    if (s->qdev.type != TYPE_ROM) {

        return false;

    }

    if (!bdrv_is_inserted(s->qdev.conf.bs)) {

        return false;

    }

    bdrv_get_geometry(s->qdev.conf.bs, &nb_sectors);

    return nb_sectors > CD_MAX_SECTORS;

}

static inline bool media_is_cd(SCSIDiskState *s)

{

    uint64_t nb_sectors;

    if (s->qdev.type != TYPE_ROM) {

        return false;

    }

    if (!bdrv_is_inserted(s->qdev.conf.bs)) {

        return false;

    }

    bdrv_get_geometry(s->qdev.conf.bs, &nb_sectors);

    return nb_sectors <= CD_MAX_SECTORS;

}

static int scsi_read_dvd_structure(SCSIDiskState *s, SCSIDiskReq *r,

                                   uint8_t *outbuf)

{

    static const int rds_caps_size[5] = {

        [0] = 2048 + 4,

        [1] = 4 + 4,

        [3] = 188 + 4,

        [4] = 2048 + 4,

    };

    uint8_t media = r->req.cmd.buf[1];

    uint8_t layer = r->req.cmd.buf[6];

    uint8_t format = r->req.cmd.buf[7];

    int size = -1;

    if (s->qdev.type != TYPE_ROM) {

        return -1;

    }

    if (media != 0) {

        scsi_check_condition(r, SENSE_CODE(INVALID_FIELD));

        return -1;

    }

    if (format != 0xff) {

        if (s->tray_open || !bdrv_is_inserted(s->qdev.conf.bs)) {

            scsi_check_condition(r, SENSE_CODE(NO_MEDIUM));

            return -1;

        }

        if (media_is_cd(s)) {

            scsi_check_condition(r, SENSE_CODE(INCOMPATIBLE_FORMAT));

            return -1;

        }

        if (format >= ARRAY_SIZE(rds_caps_size)) {

            return -1;

        }

        size = rds_caps_size[format];

        memset(outbuf, 0, size);

    }

    switch (format) {

    case 0x00: {

        /* Physical format information */

        uint64_t nb_sectors;

        if (layer != 0) {

            goto fail;

        }

        bdrv_get_geometry(s->qdev.conf.bs, &nb_sectors);

        outbuf[4] = 1;   /* DVD-ROM, part version 1 */

        outbuf[5] = 0xf; /* 120mm disc, minimum rate unspecified */

        outbuf[6] = 1;   /* one layer, read-only (per MMC-2 spec) */

        outbuf[7] = 0;   /* default densities */

        stl_be_p(&outbuf[12], (nb_sectors >> 2) - 1); /* end sector */

        stl_be_p(&outbuf[16], (nb_sectors >> 2) - 1); /* l0 end sector */

        break;

    }

    case 0x01: /* DVD copyright information, all zeros */

        break;

    case 0x03: /* BCA information - invalid field for no BCA info */

        return -1;

    case 0x04: /* DVD disc manufacturing information, all zeros */

        break;

    case 0xff: { /* List capabilities */

        int i;

        size = 4;

        for (i = 0; i < ARRAY_SIZE(rds_caps_size); i++) {

            if (!rds_caps_size[i]) {

                continue;

            }

            outbuf[size] = i;

            outbuf[size + 1] = 0x40; /* Not writable, readable */

            stw_be_p(&outbuf[size + 2], rds_caps_size[i]);

            size += 4;

        }

        break;

     }

    default:

        return -1;

    }

    /* Size of buffer, not including 2 byte size field */

    stw_be_p(outbuf, size - 2);

    return size;

fail:

    return -1;

}

static int scsi_event_status_media(SCSIDiskState *s, uint8_t *outbuf)

{

    uint8_t event_code, media_status;

    media_status = 0;

    if (s->tray_open) {

        media_status = MS_TRAY_OPEN;

    } else if (bdrv_is_inserted(s->qdev.conf.bs)) {

        media_status = MS_MEDIA_PRESENT;

    }

    /* Event notification descriptor */

    event_code = MEC_NO_CHANGE;

    if (media_status != MS_TRAY_OPEN) {

        if (s->media_event) {

            event_code = MEC_NEW_MEDIA;

            s->media_event = false;

        } else if (s->eject_request) {

            event_code = MEC_EJECT_REQUESTED;

            s->eject_request = false;

        }

    }

    outbuf[0] = event_code;

    outbuf[1] = media_status;

    /* These fields are reserved, just clear them. */

    outbuf[2] = 0;

    outbuf[3] = 0;

    return 4;

}

static int scsi_get_event_status_notification(SCSIDiskState *s, SCSIDiskReq *r,

                                              uint8_t *outbuf)

{

    int size;

    uint8_t *buf = r->req.cmd.buf;

    uint8_t notification_class_request = buf[4];

    if (s->qdev.type != TYPE_ROM) {

        return -1;

    }

    if ((buf[1] & 1) == 0) {

        /* asynchronous */

        return -1;

    }

    size = 4;

    outbuf[0] = outbuf[1] = 0;

    outbuf[3] = 1 << GESN_MEDIA; /* supported events */

    if (notification_class_request & (1 << GESN_MEDIA)) {

        outbuf[2] = GESN_MEDIA;

        size += scsi_event_status_media(s, &outbuf[size]);

    } else {

        outbuf[2] = 0x80;

    }

    stw_be_p(outbuf, size - 4);

    return size;

}

static int scsi_get_configuration(SCSIDiskState *s, uint8_t *outbuf)

{

    int current;

    if (s->qdev.type != TYPE_ROM) {

        return -1;

    }

    current = media_is_dvd(s) ? MMC_PROFILE_DVD_ROM : MMC_PROFILE_CD_ROM;

    memset(outbuf, 0, 40);

    stl_be_p(&outbuf[0], 36); /* Bytes after the data length field */

    stw_be_p(&outbuf[6], current);

    /* outbuf[8] - outbuf[19]: Feature 0 - Profile list */

    outbuf[10] = 0x03; /* persistent, current */

    outbuf[11] = 8; /* two profiles */

    stw_be_p(&outbuf[12], MMC_PROFILE_DVD_ROM);

    outbuf[14] = (current == MMC_PROFILE_DVD_ROM);

    stw_be_p(&outbuf[16], MMC_PROFILE_CD_ROM);

    outbuf[18] = (current == MMC_PROFILE_CD_ROM);

    /* outbuf[20] - outbuf[31]: Feature 1 - Core feature */

    stw_be_p(&outbuf[20], 1);

    outbuf[22] = 0x08 | 0x03; /* version 2, persistent, current */

    outbuf[23] = 8;

    stl_be_p(&outbuf[24], 1); /* SCSI */

    outbuf[28] = 1; /* DBE = 1, mandatory */

    /* outbuf[32] - outbuf[39]: Feature 3 - Removable media feature */

    stw_be_p(&outbuf[32], 3);

    outbuf[34] = 0x08 | 0x03; /* version 2, persistent, current */

    outbuf[35] = 4;

    outbuf[36] = 0x39; /* tray, load=1, eject=1, unlocked at powerup, lock=1 */

    /* TODO: Random readable, CD read, DVD read, drive serial number,

       power management */

    return 40;

}

static int scsi_emulate_mechanism_status(SCSIDiskState *s, uint8_t *outbuf)

{

    if (s->qdev.type != TYPE_ROM) {

        return -1;

    }

    memset(outbuf, 0, 8);

    outbuf[5] = 1; /* CD-ROM */

    return 8;

}

static int mode_sense_page(SCSIDiskState *s, int page, uint8_t **p_outbuf,

                           int page_control)

{

    static const int mode_sense_valid[0x3f] = {

        [MODE_PAGE_HD_GEOMETRY]            = (1 << TYPE_DISK),

        [MODE_PAGE_FLEXIBLE_DISK_GEOMETRY] = (1 << TYPE_DISK),

        [MODE_PAGE_CACHING]                = (1 << TYPE_DISK) | (1 << TYPE_ROM),

        [MODE_PAGE_R_W_ERROR]              = (1 << TYPE_DISK) | (1 << TYPE_ROM),

        [MODE_PAGE_AUDIO_CTL]              = (1 << TYPE_ROM),

        [MODE_PAGE_CAPABILITIES]           = (1 << TYPE_ROM),

    };

    BlockDriverState *bdrv = s->qdev.conf.bs;

    int cylinders, heads, secs;

    uint8_t *p = *p_outbuf;

    if ((mode_sense_valid[page] & (1 << s->qdev.type)) == 0) {

        return -1;

    }

    p[0] = page;

    /*

     * 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 MODE_PAGE_HD_GEOMETRY:

        p[1] = 0x16;

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

            break;

        }

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

        bdrv_guess_geometry(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;

        break;

    case MODE_PAGE_FLEXIBLE_DISK_GEOMETRY:

        p[1] = 0x1e;

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

            break;

        }

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

        p[2] = 5000 >> 8;

        p[3] = 5000 & 0xff;

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

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

        p[4] = heads & 0xff;

        p[5] = secs & 0xff;

        p[6] = s->qdev.blocksize >> 8;

        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;

        break;

    case MODE_PAGE_CACHING:

        p[0] = 8;

        p[1] = 0x12;

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

            break;

        }

        if (bdrv_enable_write_cache(s->qdev.conf.bs)) {

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

        }

        break;

    case MODE_PAGE_R_W_ERROR:

        p[1] = 10;

        p[2] = 0x80; /* Automatic Write Reallocation Enabled */

        if (s->qdev.type == TYPE_ROM) {

            p[3] = 0x20; /* Read Retry Count */

        }

        break;