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

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

1 files changed, 829 insertions, 0 deletions

diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c
new file mode 100644
index 00000000..92cce20a
--- /dev/null
+++ b/hw/scsi/scsi-generic.c
@@ -0,0 +1,829 @@
+/*
+ * Generic SCSI Device support
+ *
+ * Copyright (c) 2007 Bull S.A.S.
+ * Based on code by Paul Brook
+ * Based on code by Fabrice Bellard
+ *
+ * Written by Laurent Vivier <Laurent.Vivier@bull.net>
+ *
+ * This code is licensed under the LGPL.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qemu/ctype.h"
+#include "qemu/error-report.h"
+#include "qemu/module.h"
+#include "hw/scsi/scsi.h"
+#include "migration/qemu-file-types.h"
+#include "hw/qdev-properties.h"
+#include "hw/qdev-properties-system.h"
+#include "hw/scsi/emulation.h"
+#include "sysemu/block-backend.h"
+#include "trace.h"
+
+#ifdef __linux__
+
+#include <scsi/sg.h>
+#include "scsi/constants.h"
+
+#ifndef MAX_UINT
+#define MAX_UINT ((unsigned int)-1)
+#endif
+
+typedef struct SCSIGenericReq {
+    SCSIRequest req;
+    uint8_t *buf;
+    int buflen;
+    int len;
+    sg_io_hdr_t io_header;
+} SCSIGenericReq;
+
+static void scsi_generic_save_request(QEMUFile *f, SCSIRequest *req)
+{
+    SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+
+    qemu_put_sbe32s(f, &r->buflen);
+    if (r->buflen && r->req.cmd.mode == SCSI_XFER_TO_DEV) {
+        assert(!r->req.sg);
+        qemu_put_buffer(f, r->buf, r->req.cmd.xfer);
+    }
+}
+
+static void scsi_generic_load_request(QEMUFile *f, SCSIRequest *req)
+{
+    SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+
+    qemu_get_sbe32s(f, &r->buflen);
+    if (r->buflen && r->req.cmd.mode == SCSI_XFER_TO_DEV) {
+        assert(!r->req.sg);
+        qemu_get_buffer(f, r->buf, r->req.cmd.xfer);
+    }
+}
+
+static void scsi_free_request(SCSIRequest *req)
+{
+    SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+
+    g_free(r->buf);
+}
+
+/* Helper function for command completion.  */
+static void scsi_command_complete_noio(SCSIGenericReq *r, int ret)
+{
+    int status;
+    SCSISense sense;
+    sg_io_hdr_t *io_hdr = &r->io_header;
+
+    assert(r->req.aiocb == NULL);
+
+    if (r->req.io_canceled) {
+        scsi_req_cancel_complete(&r->req);
+        goto done;
+    }
+    if (ret < 0) {
+        status = scsi_sense_from_errno(-ret, &sense);
+        if (status == CHECK_CONDITION) {
+            scsi_req_build_sense(&r->req, sense);
+        }
+    } else if (io_hdr->host_status != SCSI_HOST_OK) {
+        scsi_req_complete_failed(&r->req, io_hdr->host_status);
+        goto done;
+    } else if (io_hdr->driver_status & SG_ERR_DRIVER_TIMEOUT) {
+        status = BUSY;
+    } else {
+        status = io_hdr->status;
+        if (io_hdr->driver_status & SG_ERR_DRIVER_SENSE) {
+            r->req.sense_len = io_hdr->sb_len_wr;
+        }
+    }
+    trace_scsi_generic_command_complete_noio(r, r->req.tag, status);
+
+    scsi_req_complete(&r->req, status);
+done:
+    scsi_req_unref(&r->req);
+}
+
+static void scsi_command_complete(void *opaque, int ret)
+{
+    SCSIGenericReq *r = (SCSIGenericReq *)opaque;
+    SCSIDevice *s = r->req.dev;
+
+    assert(r->req.aiocb != NULL);
+    r->req.aiocb = NULL;
+
+    aio_context_acquire(blk_get_aio_context(s->conf.blk));
+    scsi_command_complete_noio(r, ret);
+    aio_context_release(blk_get_aio_context(s->conf.blk));
+}
+
+static int execute_command(BlockBackend *blk,
+                           SCSIGenericReq *r, int direction,
+                           BlockCompletionFunc *complete)
+{
+    SCSIDevice *s = r->req.dev;
+
+    r->io_header.interface_id = 'S';
+    r->io_header.dxfer_direction = direction;
+    r->io_header.dxferp = r->buf;
+    r->io_header.dxfer_len = r->buflen;
+    r->io_header.cmdp = r->req.cmd.buf;
+    r->io_header.cmd_len = r->req.cmd.len;
+    r->io_header.mx_sb_len = sizeof(r->req.sense);
+    r->io_header.sbp = r->req.sense;
+    r->io_header.timeout = s->io_timeout * 1000;
+    r->io_header.usr_ptr = r;
+    r->io_header.flags |= SG_FLAG_DIRECT_IO;
+
+    trace_scsi_generic_aio_sgio_command(r->req.tag, r->req.cmd.buf[0],
+                                        r->io_header.timeout);
+    r->req.aiocb = blk_aio_ioctl(blk, SG_IO, &r->io_header, complete, r);
+    if (r->req.aiocb == NULL) {
+        return -EIO;
+    }
+
+    return 0;
+}
+
+static uint64_t calculate_max_transfer(SCSIDevice *s)
+{
+    uint64_t max_transfer = blk_get_max_hw_transfer(s->conf.blk);
+    uint32_t max_iov = blk_get_max_hw_iov(s->conf.blk);
+
+    assert(max_transfer);
+    max_transfer = MIN_NON_ZERO(max_transfer,
+                                max_iov * qemu_real_host_page_size());
+
+    return max_transfer / s->blocksize;
+}
+
+static int scsi_handle_inquiry_reply(SCSIGenericReq *r, SCSIDevice *s, int len)
+{
+    uint8_t page, page_idx;
+
+    /*
+     *  EVPD set to zero returns the standard INQUIRY data.
+     *
+     *  Check if scsi_version is unset (-1) to avoid re-defining it
+     *  each time an INQUIRY with standard data is received.
+     *  scsi_version is initialized with -1 in scsi_generic_reset
+     *  and scsi_disk_reset, making sure that we'll set the
+     *  scsi_version after a reset. If the version field of the
+     *  INQUIRY response somehow changes after a guest reboot,
+     *  we'll be able to keep track of it.
+     *
+     *  On SCSI-2 and older, first 3 bits of byte 2 is the
+     *  ANSI-approved version, while on later versions the
+     *  whole byte 2 contains the version. Check if we're dealing
+     *  with a newer version and, in that case, assign the
+     *  whole byte.
+     */
+    if (s->scsi_version == -1 && !(r->req.cmd.buf[1] & 0x01)) {
+        s->scsi_version = r->buf[2] & 0x07;
+        if (s->scsi_version > 2) {
+            s->scsi_version = r->buf[2];
+        }
+    }
+
+    if ((s->type == TYPE_DISK || s->type == TYPE_ZBC) &&
+        (r->req.cmd.buf[1] & 0x01)) {
+        page = r->req.cmd.buf[2];
+        if (page == 0xb0) {
+            uint64_t max_transfer = calculate_max_transfer(s);
+            stl_be_p(&r->buf[8], max_transfer);
+            /* Also take care of the opt xfer len. */
+            stl_be_p(&r->buf[12],
+                    MIN_NON_ZERO(max_transfer, ldl_be_p(&r->buf[12])));
+        } else if (s->needs_vpd_bl_emulation && page == 0x00 && r->buflen >= 4) {
+            /*
+             * Now we're capable of supplying the VPD Block Limits
+             * response if the hardware can't. Add it in the INQUIRY
+             * Supported VPD pages response in case we are using the
+             * emulation for this device.
+             *
+             * This way, the guest kernel will be aware of the support
+             * and will use it to proper setup the SCSI device.
+             *
+             * VPD page numbers must be sorted, so insert 0xb0 at the
+             * right place with an in-place insert.  When the while loop
+             * begins the device response is at r[0] to r[page_idx - 1].
+             */
+            page_idx = lduw_be_p(r->buf + 2) + 4;
+            page_idx = MIN(page_idx, r->buflen);
+            while (page_idx > 4 && r->buf[page_idx - 1] >= 0xb0) {
+                if (page_idx < r->buflen) {
+                    r->buf[page_idx] = r->buf[page_idx - 1];
+                }
+                page_idx--;
+            }
+            if (page_idx < r->buflen) {
+                r->buf[page_idx] = 0xb0;
+            }
+            stw_be_p(r->buf + 2, lduw_be_p(r->buf + 2) + 1);
+
+            if (len < r->buflen) {
+                len++;
+            }
+        }
+    }
+    return len;
+}
+
+static int scsi_generic_emulate_block_limits(SCSIGenericReq *r, SCSIDevice *s)
+{
+    int len;
+    uint8_t buf[64];
+
+    SCSIBlockLimits bl = {
+        .max_io_sectors = calculate_max_transfer(s),
+    };
+
+    memset(r->buf, 0, r->buflen);
+    stb_p(buf, s->type);
+    stb_p(buf + 1, 0xb0);
+    len = scsi_emulate_block_limits(buf + 4, &bl);
+    assert(len <= sizeof(buf) - 4);
+    stw_be_p(buf + 2, len);
+
+    memcpy(r->buf, buf, MIN(r->buflen, len + 4));
+
+    r->io_header.sb_len_wr = 0;
+
+    /*
+    * We have valid contents in the reply buffer but the
+    * io_header can report a sense error coming from
+    * the hardware in scsi_command_complete_noio. Clean
+    * up the io_header to avoid reporting it.
+    */
+    r->io_header.driver_status = 0;
+    r->io_header.status = 0;
+
+    return r->buflen;
+}
+
+static void scsi_read_complete(void * opaque, int ret)
+{
+    SCSIGenericReq *r = (SCSIGenericReq *)opaque;
+    SCSIDevice *s = r->req.dev;
+    int len;
+
+    assert(r->req.aiocb != NULL);
+    r->req.aiocb = NULL;
+
+    aio_context_acquire(blk_get_aio_context(s->conf.blk));
+
+    if (ret || r->req.io_canceled) {
+        scsi_command_complete_noio(r, ret);
+        goto done;
+    }
+
+    len = r->io_header.dxfer_len - r->io_header.resid;
+    trace_scsi_generic_read_complete(r->req.tag, len);
+
+    r->len = -1;
+
+    if (r->io_header.driver_status & SG_ERR_DRIVER_SENSE) {
+        SCSISense sense =
+            scsi_parse_sense_buf(r->req.sense, r->io_header.sb_len_wr);
+
+        /*
+         * Check if this is a VPD Block Limits request that
+         * resulted in sense error but would need emulation.
+         * In this case, emulate a valid VPD response.
+         */
+        if (sense.key == ILLEGAL_REQUEST &&
+            s->needs_vpd_bl_emulation &&
+            r->req.cmd.buf[0] == INQUIRY &&
+            (r->req.cmd.buf[1] & 0x01) &&
+            r->req.cmd.buf[2] == 0xb0) {
+            len = scsi_generic_emulate_block_limits(r, s);
+            /*
+             * It's okay to jup to req_complete: no need to
+             * let scsi_handle_inquiry_reply handle an
+             * INQUIRY VPD BL request we created manually.
+             */
+        }
+        if (sense.key) {
+            goto req_complete;
+        }
+    }
+
+    if (r->io_header.host_status != SCSI_HOST_OK ||
+        (r->io_header.driver_status & SG_ERR_DRIVER_TIMEOUT) ||
+        r->io_header.status != GOOD ||
+        len == 0) {
+        scsi_command_complete_noio(r, 0);
+        goto done;
+    }
+
+    /* Snoop READ CAPACITY output to set the blocksize.  */
+    if (r->req.cmd.buf[0] == READ_CAPACITY_10 &&
+        (ldl_be_p(&r->buf[0]) != 0xffffffffU || s->max_lba == 0)) {
+        s->blocksize = ldl_be_p(&r->buf[4]);
+        s->max_lba = ldl_be_p(&r->buf[0]) & 0xffffffffULL;
+    } else if (r->req.cmd.buf[0] == SERVICE_ACTION_IN_16 &&
+               (r->req.cmd.buf[1] & 31) == SAI_READ_CAPACITY_16) {
+        s->blocksize = ldl_be_p(&r->buf[8]);
+        s->max_lba = ldq_be_p(&r->buf[0]);
+    }
+
+    /*
+     * Patch MODE SENSE device specific parameters if the BDS is opened
+     * readonly.
+     */
+    if ((s->type == TYPE_DISK || s->type == TYPE_TAPE || s->type == TYPE_ZBC) &&
+        !blk_is_writable(s->conf.blk) &&
+        (r->req.cmd.buf[0] == MODE_SENSE ||
+         r->req.cmd.buf[0] == MODE_SENSE_10) &&
+        (r->req.cmd.buf[1] & 0x8) == 0) {
+        if (r->req.cmd.buf[0] == MODE_SENSE) {
+            r->buf[2] |= 0x80;
+        } else  {
+            r->buf[3] |= 0x80;
+        }
+    }
+    if (r->req.cmd.buf[0] == INQUIRY) {
+        len = scsi_handle_inquiry_reply(r, s, len);
+    }
+
+req_complete:
+    scsi_req_data(&r->req, len);
+    scsi_req_unref(&r->req);
+
+done:
+    aio_context_release(blk_get_aio_context(s->conf.blk));
+}
+
+/* Read more data from scsi device into buffer.  */
+static void scsi_read_data(SCSIRequest *req)
+{
+    SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+    SCSIDevice *s = r->req.dev;
+    int ret;
+
+    trace_scsi_generic_read_data(req->tag);
+
+    /* The request is used as the AIO opaque value, so add a ref.  */
+    scsi_req_ref(&r->req);
+    if (r->len == -1) {
+        scsi_command_complete_noio(r, 0);
+        return;
+    }
+
+    ret = execute_command(s->conf.blk, r, SG_DXFER_FROM_DEV,
+                          scsi_read_complete);
+    if (ret < 0) {
+        scsi_command_complete_noio(r, ret);
+    }
+}
+
+static void scsi_write_complete(void * opaque, int ret)
+{
+    SCSIGenericReq *r = (SCSIGenericReq *)opaque;
+    SCSIDevice *s = r->req.dev;
+
+    trace_scsi_generic_write_complete(ret);
+
+    assert(r->req.aiocb != NULL);
+    r->req.aiocb = NULL;
+
+    aio_context_acquire(blk_get_aio_context(s->conf.blk));
+
+    if (ret || r->req.io_canceled) {
+        scsi_command_complete_noio(r, ret);
+        goto done;
+    }
+
+    if (r->req.cmd.buf[0] == MODE_SELECT && r->req.cmd.buf[4] == 12 &&
+        s->type == TYPE_TAPE) {
+        s->blocksize = (r->buf[9] << 16) | (r->buf[10] << 8) | r->buf[11];
+        trace_scsi_generic_write_complete_blocksize(s->blocksize);
+    }
+
+    scsi_command_complete_noio(r, ret);
+
+done:
+    aio_context_release(blk_get_aio_context(s->conf.blk));
+}
+
+/* Write data to a scsi device.  Returns nonzero on failure.
+   The transfer may complete asynchronously.  */
+static void scsi_write_data(SCSIRequest *req)
+{
+    SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+    SCSIDevice *s = r->req.dev;
+    int ret;
+
+    trace_scsi_generic_write_data(req->tag);
+    if (r->len == 0) {
+        r->len = r->buflen;
+        scsi_req_data(&r->req, r->len);
+        return;
+    }
+
+    /* The request is used as the AIO opaque value, so add a ref.  */
+    scsi_req_ref(&r->req);
+    ret = execute_command(s->conf.blk, r, SG_DXFER_TO_DEV, scsi_write_complete);
+    if (ret < 0) {
+        scsi_command_complete_noio(r, ret);
+    }
+}
+
+/* Return a pointer to the data buffer.  */
+static uint8_t *scsi_get_buf(SCSIRequest *req)
+{
+    SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+
+    return r->buf;
+}
+
+static void scsi_generic_command_dump(uint8_t *cmd, int len)
+{
+    int i;
+    char *line_buffer, *p;
+
+    line_buffer = g_malloc(len * 5 + 1);
+
+    for (i = 0, p = line_buffer; i < len; i++) {
+        p += sprintf(p, " 0x%02x", cmd[i]);
+    }
+    trace_scsi_generic_send_command(line_buffer);
+
+    g_free(line_buffer);
+}
+
+/* Execute a scsi command.  Returns the length of the data expected by the
+   command.  This will be Positive for data transfers from the device
+   (eg. disk reads), negative for transfers to the device (eg. disk writes),
+   and zero if the command does not transfer any data.  */
+
+static int32_t scsi_send_command(SCSIRequest *req, uint8_t *cmd)
+{
+    SCSIGenericReq *r = DO_UPCAST(SCSIGenericReq, req, req);
+    SCSIDevice *s = r->req.dev;
+    int ret;
+
+    if (trace_event_get_state_backends(TRACE_SCSI_GENERIC_SEND_COMMAND)) {
+        scsi_generic_command_dump(cmd, r->req.cmd.len);
+    }
+
+    if (r->req.cmd.xfer == 0) {
+        g_free(r->buf);
+        r->buflen = 0;
+        r->buf = NULL;
+        /* The request is used as the AIO opaque value, so add a ref.  */
+        scsi_req_ref(&r->req);
+        ret = execute_command(s->conf.blk, r, SG_DXFER_NONE,
+                              scsi_command_complete);
+        if (ret < 0) {
+            scsi_command_complete_noio(r, ret);
+            return 0;
+        }
+        return 0;
+    }
+
+    if (r->buflen != r->req.cmd.xfer) {
+        g_free(r->buf);
+        r->buf = g_malloc(r->req.cmd.xfer);
+        r->buflen = r->req.cmd.xfer;
+    }
+
+    memset(r->buf, 0, r->buflen);
+    r->len = r->req.cmd.xfer;
+    if (r->req.cmd.mode == SCSI_XFER_TO_DEV) {
+        r->len = 0;
+        return -r->req.cmd.xfer;
+    } else {
+        return r->req.cmd.xfer;
+    }
+}
+
+static int read_naa_id(const uint8_t *p, uint64_t *p_wwn)
+{
+    int i;
+
+    if ((p[1] & 0xF) == 3) {
+        /* NAA designator type */
+        if (p[3] != 8) {
+            return -EINVAL;
+        }
+        *p_wwn = ldq_be_p(p + 4);
+        return 0;
+    }
+
+    if ((p[1] & 0xF) == 8) {
+        /* SCSI name string designator type */
+        if (p[3] < 20 || memcmp(&p[4], "naa.", 4)) {
+            return -EINVAL;
+        }
+        if (p[3] > 20 && p[24] != ',') {
+            return -EINVAL;
+        }
+        *p_wwn = 0;
+        for (i = 8; i < 24; i++) {
+            char c = qemu_toupper(p[i]);
+            c -= (c >= '0' && c <= '9' ? '0' : 'A' - 10);
+            *p_wwn = (*p_wwn << 4) | c;
+        }
+        return 0;
+    }
+
+    return -EINVAL;
+}
+
+int scsi_SG_IO_FROM_DEV(BlockBackend *blk, uint8_t *cmd, uint8_t cmd_size,
+                        uint8_t *buf, uint8_t buf_size, uint32_t timeout)
+{
+    sg_io_hdr_t io_header;
+    uint8_t sensebuf[8];
+    int ret;
+
+    memset(&io_header, 0, sizeof(io_header));
+    io_header.interface_id = 'S';
+    io_header.dxfer_direction = SG_DXFER_FROM_DEV;
+    io_header.dxfer_len = buf_size;
+    io_header.dxferp = buf;
+    io_header.cmdp = cmd;
+    io_header.cmd_len = cmd_size;
+    io_header.mx_sb_len = sizeof(sensebuf);
+    io_header.sbp = sensebuf;
+    io_header.timeout = timeout * 1000;
+
+    trace_scsi_generic_ioctl_sgio_command(cmd[0], io_header.timeout);
+    ret = blk_ioctl(blk, SG_IO, &io_header);
+    if (ret < 0 || io_header.status ||
+        io_header.driver_status || io_header.host_status) {
+        trace_scsi_generic_ioctl_sgio_done(cmd[0], ret, io_header.status,
+                                           io_header.host_status);
+        return -1;
+    }
+    return 0;
+}
+
+/*
+ * Executes an INQUIRY request with EVPD set to retrieve the
+ * available VPD pages of the device. If the device does
+ * not support the Block Limits page (page 0xb0), set
+ * the needs_vpd_bl_emulation flag for future use.
+ */
+static void scsi_generic_set_vpd_bl_emulation(SCSIDevice *s)
+{
+    uint8_t cmd[6];
+    uint8_t buf[250];
+    uint8_t page_len;
+    int ret, i;
+
+    memset(cmd, 0, sizeof(cmd));
+    memset(buf, 0, sizeof(buf));
+    cmd[0] = INQUIRY;
+    cmd[1] = 1;
+    cmd[2] = 0x00;
+    cmd[4] = sizeof(buf);
+
+    ret = scsi_SG_IO_FROM_DEV(s->conf.blk, cmd, sizeof(cmd),
+                              buf, sizeof(buf), s->io_timeout);
+    if (ret < 0) {
+        /*
+         * Do not assume anything if we can't retrieve the
+         * INQUIRY response to assert the VPD Block Limits
+         * support.
+         */
+        s->needs_vpd_bl_emulation = false;
+        return;
+    }
+
+    page_len = buf[3];
+    for (i = 4; i < MIN(sizeof(buf), page_len + 4); i++) {
+        if (buf[i] == 0xb0) {
+            s->needs_vpd_bl_emulation = false;
+            return;
+        }
+    }
+    s->needs_vpd_bl_emulation = true;
+}
+
+static void scsi_generic_read_device_identification(SCSIDevice *s)
+{
+    uint8_t cmd[6];
+    uint8_t buf[250];
+    int ret;
+    int i, len;
+
+    memset(cmd, 0, sizeof(cmd));
+    memset(buf, 0, sizeof(buf));
+    cmd[0] = INQUIRY;
+    cmd[1] = 1;
+    cmd[2] = 0x83;
+    cmd[4] = sizeof(buf);
+
+    ret = scsi_SG_IO_FROM_DEV(s->conf.blk, cmd, sizeof(cmd),
+                              buf, sizeof(buf), s->io_timeout);
+    if (ret < 0) {
+        return;
+    }
+
+    len = MIN((buf[2] << 8) | buf[3], sizeof(buf) - 4);
+    for (i = 0; i + 3 <= len; ) {
+        const uint8_t *p = &buf[i + 4];
+        uint64_t wwn;
+
+        if (i + (p[3] + 4) > len) {
+            break;
+        }
+
+        if ((p[1] & 0x10) == 0) {
+            /* Associated with the logical unit */
+            if (read_naa_id(p, &wwn) == 0) {
+                s->wwn = wwn;
+            }
+        } else if ((p[1] & 0x10) == 0x10) {
+            /* Associated with the target port */
+            if (read_naa_id(p, &wwn) == 0) {
+                s->port_wwn = wwn;
+            }
+        }
+
+        i += p[3] + 4;
+    }
+}
+
+void scsi_generic_read_device_inquiry(SCSIDevice *s)
+{
+    scsi_generic_read_device_identification(s);
+    if (s->type == TYPE_DISK || s->type == TYPE_ZBC) {
+        scsi_generic_set_vpd_bl_emulation(s);
+    } else {
+        s->needs_vpd_bl_emulation = false;
+    }
+}
+
+static int get_stream_blocksize(BlockBackend *blk)
+{
+    uint8_t cmd[6];
+    uint8_t buf[12];
+    int ret;
+
+    memset(cmd, 0, sizeof(cmd));
+    memset(buf, 0, sizeof(buf));
+    cmd[0] = MODE_SENSE;
+    cmd[4] = sizeof(buf);
+
+    ret = scsi_SG_IO_FROM_DEV(blk, cmd, sizeof(cmd), buf, sizeof(buf), 6);
+    if (ret < 0) {
+        return -1;
+    }
+
+    return (buf[9] << 16) | (buf[10] << 8) | buf[11];
+}
+
+static void scsi_generic_reset(DeviceState *dev)
+{
+    SCSIDevice *s = SCSI_DEVICE(dev);
+
+    s->scsi_version = s->default_scsi_version;
+    scsi_device_purge_requests(s, SENSE_CODE(RESET));
+}
+
+static void scsi_generic_realize(SCSIDevice *s, Error **errp)
+{
+    int rc;
+    int sg_version;
+    struct sg_scsi_id scsiid;
+
+    if (!s->conf.blk) {
+        error_setg(errp, "drive property not set");
+        return;
+    }
+
+    if (blk_get_on_error(s->conf.blk, 0) != BLOCKDEV_ON_ERROR_ENOSPC &&
+        blk_get_on_error(s->conf.blk, 0) != BLOCKDEV_ON_ERROR_REPORT) {
+        error_setg(errp, "Device doesn't support drive option werror");
+        return;
+    }
+    if (blk_get_on_error(s->conf.blk, 1) != BLOCKDEV_ON_ERROR_REPORT) {
+        error_setg(errp, "Device doesn't support drive option rerror");
+        return;
+    }
+
+    /* check we are using a driver managing SG_IO (version 3 and after */
+    rc = blk_ioctl(s->conf.blk, SG_GET_VERSION_NUM, &sg_version);
+    if (rc < 0) {
+        error_setg_errno(errp, -rc, "cannot get SG_IO version number");
+        if (rc != -EPERM) {
+            error_append_hint(errp, "Is this a SCSI device?\n");
+        }
+        return;
+    }
+    if (sg_version < 30000) {
+        error_setg(errp, "scsi generic interface too old");
+        return;
+    }
+
+    /* get LUN of the /dev/sg? */
+    if (blk_ioctl(s->conf.blk, SG_GET_SCSI_ID, &scsiid)) {
+        error_setg(errp, "SG_GET_SCSI_ID ioctl failed");
+        return;
+    }
+    if (!blkconf_apply_backend_options(&s->conf,
+                                       !blk_supports_write_perm(s->conf.blk),
+                                       true, errp)) {
+        return;
+    }
+
+    /* define device state */
+    s->type = scsiid.scsi_type;
+    trace_scsi_generic_realize_type(s->type);
+
+    switch (s->type) {
+    case TYPE_TAPE:
+        s->blocksize = get_stream_blocksize(s->conf.blk);
+        if (s->blocksize == -1) {
+            s->blocksize = 0;
+        }
+        break;
+
+        /* Make a guess for block devices, we'll fix it when the guest sends.
+         * READ CAPACITY.  If they don't, they likely would assume these sizes
+         * anyway. (TODO: they could also send MODE SENSE).
+         */
+    case TYPE_ROM:
+    case TYPE_WORM:
+        s->blocksize = 2048;
+        break;
+    default:
+        s->blocksize = 512;
+        break;
+    }
+
+    trace_scsi_generic_realize_blocksize(s->blocksize);
+
+    /* Only used by scsi-block, but initialize it nevertheless to be clean.  */
+    s->default_scsi_version = -1;
+    s->io_timeout = DEFAULT_IO_TIMEOUT;
+    scsi_generic_read_device_inquiry(s);
+}
+
+const SCSIReqOps scsi_generic_req_ops = {
+    .size         = sizeof(SCSIGenericReq),
+    .free_req     = scsi_free_request,
+    .send_command = scsi_send_command,
+    .read_data    = scsi_read_data,
+    .write_data   = scsi_write_data,
+    .get_buf      = scsi_get_buf,
+    .load_request = scsi_generic_load_request,
+    .save_request = scsi_generic_save_request,
+};
+
+static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag, uint32_t lun,
+                                     uint8_t *buf, void *hba_private)
+{
+    return scsi_req_alloc(&scsi_generic_req_ops, d, tag, lun, hba_private);
+}
+
+static Property scsi_generic_properties[] = {
+    DEFINE_PROP_DRIVE("drive", SCSIDevice, conf.blk),
+    DEFINE_PROP_BOOL("share-rw", SCSIDevice, conf.share_rw, false),
+    DEFINE_PROP_UINT32("io_timeout", SCSIDevice, io_timeout,
+                       DEFAULT_IO_TIMEOUT),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static int scsi_generic_parse_cdb(SCSIDevice *dev, SCSICommand *cmd,
+                                  uint8_t *buf, size_t buf_len,
+                                  void *hba_private)
+{
+    return scsi_bus_parse_cdb(dev, cmd, buf, buf_len, hba_private);
+}
+
+static void scsi_generic_class_initfn(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    SCSIDeviceClass *sc = SCSI_DEVICE_CLASS(klass);
+
+    sc->realize      = scsi_generic_realize;
+    sc->alloc_req    = scsi_new_request;
+    sc->parse_cdb    = scsi_generic_parse_cdb;
+    dc->fw_name = "disk";
+    dc->desc = "pass through generic scsi device (/dev/sg*)";
+    dc->reset = scsi_generic_reset;
+    device_class_set_props(dc, scsi_generic_properties);
+    dc->vmsd  = &vmstate_scsi_device;
+}
+
+static const TypeInfo scsi_generic_info = {
+    .name          = "scsi-generic",
+    .parent        = TYPE_SCSI_DEVICE,
+    .instance_size = sizeof(SCSIDevice),
+    .class_init    = scsi_generic_class_initfn,
+};
+
+static void scsi_generic_register_types(void)
+{
+    type_register_static(&scsi_generic_info);
+}
+
+type_init(scsi_generic_register_types)
+
+#endif /* __linux__ */