Commit 336a6915 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Kevin Wolf
Browse files

scsi-disk: add scsi-block for device passthrough 



scsi-block is a new device that supports device passthrough of Linux
block devices (i.e. /dev/sda, not /dev/sg0).  It uses SG_IO for commands
other than I/O commands, and regular AIO read/writes for I/O commands.
Besides being simpler to configure (no mapping required to scsi-generic
device names), this removes the need for a large bounce buffer and,
in the future, will get scatter/gather support for free from scsi-disk.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 71544d30

hw/scsi-disk.c

+118 −0
Original line number Diff line number Diff line
@@ -39,6 +39,10 @@ do { fprintf(stderr, "scsi-disk: " fmt , ## __VA_ARGS__); } while (0) 
#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
@@ -1588,6 +1592,105 @@ static SCSIRequest *scsi_new_request(SCSIDevice *d, uint32_t tag, uint32_t lun, 
    return req;

}



#ifdef __linux__

static int get_device_type(SCSIDiskState *s)

{

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

    uint8_t cmd[16];

    uint8_t buf[36];

    uint8_t sensebuf[8];

    sg_io_hdr_t io_header;

    int ret;



    memset(cmd, 0, sizeof(cmd));

    memset(buf, 0, sizeof(buf));

    cmd[0] = INQUIRY;

    cmd[4] = sizeof(buf);



    memset(&io_header, 0, sizeof(io_header));

    io_header.interface_id = 'S';

    io_header.dxfer_direction = SG_DXFER_FROM_DEV;

    io_header.dxfer_len = sizeof(buf);

    io_header.dxferp = buf;

    io_header.cmdp = cmd;

    io_header.cmd_len = sizeof(cmd);

    io_header.mx_sb_len = sizeof(sensebuf);

    io_header.sbp = sensebuf;

    io_header.timeout = 6000; /* XXX */



    ret = bdrv_ioctl(bdrv, SG_IO, &io_header);

    if (ret < 0 || io_header.driver_status || io_header.host_status) {

        return -1;

    }

    s->qdev.type = buf[0];

    s->removable = (buf[1] & 0x80) != 0;

    return 0;

}



static int scsi_block_initfn(SCSIDevice *dev)

{

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

    int sg_version;

    int rc;



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

        error_report("scsi-block: drive property not set");

        return -1;

    }



    /* check we are using a driver managing SG_IO (version 3 and after) */

    if (bdrv_ioctl(s->qdev.conf.bs, SG_GET_VERSION_NUM, &sg_version) < 0 ||

        sg_version < 30000) {

        error_report("scsi-block: scsi generic interface too old");

        return -1;

    }



    /* get device type from INQUIRY data */

    rc = get_device_type(s);

    if (rc < 0) {

        error_report("scsi-block: INQUIRY failed");

        return -1;

    }



    /* Make a guess for the block size, we'll fix it when the guest sends.

     * READ CAPACITY.  If they don't, they likely would assume these sizes

     * anyway. (TODO: check in /sys).

     */

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

        s->qdev.blocksize = 2048;

    } else {

        s->qdev.blocksize = 512;

    }

    return scsi_initfn(&s->qdev);

}



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

                                           uint32_t lun, uint8_t *buf,

                                           void *hba_private)

{

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



    switch (buf[0]) {

    case READ_6:

    case READ_10:

    case READ_12:

    case READ_16:

    case WRITE_6:

    case WRITE_10:

    case WRITE_12:

    case WRITE_16:

    case WRITE_VERIFY_10:

    case WRITE_VERIFY_12:

    case WRITE_VERIFY_16:

        return scsi_req_alloc(&scsi_disk_reqops, &s->qdev, tag, lun,

                              hba_private);

    }



    return scsi_req_alloc(&scsi_generic_req_ops, &s->qdev, tag, lun,

                          hba_private);

}

#endif



#define DEFINE_SCSI_DISK_PROPERTIES()                           \

    DEFINE_BLOCK_PROPERTIES(SCSIDiskState, qdev.conf),          \

    DEFINE_PROP_STRING("ver",  SCSIDiskState, version),         \
@@ -1623,6 +1726,21 @@ static SCSIDeviceInfo scsi_disk_info[] = { 
            DEFINE_SCSI_DISK_PROPERTIES(),

            DEFINE_PROP_END_OF_LIST(),

        },

#ifdef __linux__

    },{

        .qdev.name    = "scsi-block",

        .qdev.fw_name = "disk",

        .qdev.desc    = "SCSI block device passthrough",

        .qdev.size    = sizeof(SCSIDiskState),

        .qdev.reset   = scsi_disk_reset,

        .init         = scsi_block_initfn,

        .destroy      = scsi_destroy,

        .alloc_req    = scsi_block_new_request,

        .qdev.props   = (Property[]) {

            DEFINE_SCSI_DISK_PROPERTIES(),

            DEFINE_PROP_END_OF_LIST(),

        },

#endif

    },{

        .qdev.name    = "scsi-disk", /* legacy -device scsi-disk */

        .qdev.fw_name = "disk",