scsi-disk.c

xen 3.2.2 源码

/*
 * SCSI Device emulation
 *
 * Copyright (c) 2006 CodeSourcery.
 * Based on code by Fabrice Bellard
 *
 * Written by Paul Brook
 *
 * This code is licenced under the LGPL.
 *
 * Note that this file only handles the SCSI architecture model and device
 * commands.  Emultion of interface/link layer protocols is handled by
 * the host adapter emulation.
 */

//#define DEBUG_SCSI

#ifdef DEBUG_SCSI
#define DPRINTF(fmt, args...) \
do { printf("scsi-disk: " fmt , ##args); } while (0)
#else
#define DPRINTF(fmt, args...) do {} while(0)
#endif

#define BADF(fmt, args...) \
do { fprintf(stderr, "scsi-disk: " fmt , ##args); } while (0)

#include "vl.h"

#define SENSE_NO_SENSE        0
#define SENSE_NOT_READY       2
#define SENSE_HARDWARE_ERROR  4
#define SENSE_ILLEGAL_REQUEST 5

#define SCSI_DMA_BUF_SIZE    65536

typedef struct SCSIRequest {
    SCSIDevice *dev;
    uint32_t tag;
    /* ??? We should probably keep track of whether the data trasfer is
       a read or a write.  Currently we rely on the host getting it right.  */
    /* Both sector and sector_count are in terms of qemu 512 byte blocks.  */
    int sector;
    int sector_count;
    /* The amounnt of data in the buffer.  */
    int buf_len;
    uint8_t dma_buf[SCSI_DMA_BUF_SIZE];
    BlockDriverAIOCB *aiocb;
    struct SCSIRequest *next;
} SCSIRequest;

struct SCSIDevice
{
    BlockDriverState *bdrv;
    SCSIRequest *requests;
    /* 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;
    int sense;
    int tcq;
    /* Completion functions may be called from either scsi_{read,write}_data
       or from the AIO completion routines.  */
    scsi_completionfn completion;
    void *opaque;
};

/* Global pool of SCSIRequest structures.  */
static SCSIRequest *free_requests = NULL;

static SCSIRequest *scsi_new_request(SCSIDevice *s, uint32_t tag)
{
    SCSIRequest *r;

    if (free_requests) {
        r = free_requests;
        free_requests = r->next;
    } else {
        r = qemu_malloc(sizeof(SCSIRequest));
    }
    r->dev = s;
    r->tag = tag;
    r->sector_count = 0;
    r->buf_len = 0;
    r->aiocb = NULL;

    r->next = s->requests;
    s->requests = r;
    return r;
}

static void scsi_remove_request(SCSIRequest *r)
{
    SCSIRequest *last;
    SCSIDevice *s = r->dev;

    if (s->requests == r) {
        s->requests = r->next;
    } else {
        last = s->requests;
        while (last && last->next != r)
            last = last->next;
        if (last) {
            last->next = r->next;
        } else {
            BADF("Orphaned request\n");
        }
    }
    r->next = free_requests;
    free_requests = r;
}

static SCSIRequest *scsi_find_request(SCSIDevice *s, uint32_t tag)
{
    SCSIRequest *r;

    r = s->requests;
    while (r && r->tag != tag)
        r = r->next;

    return r;
}

/* Helper function for command completion.  */
static void scsi_command_complete(SCSIRequest *r, int sense)
{
    SCSIDevice *s = r->dev;
    uint32_t tag;
    DPRINTF("Command complete tag=0x%x sense=%d\n", r->tag, sense);
    s->sense = sense;
    tag = r->tag;
    scsi_remove_request(r);
    s->completion(s->opaque, SCSI_REASON_DONE, tag, sense);
}

/* Cancel a pending data transfer.  */
void scsi_cancel_io(SCSIDevice *s, uint32_t tag)
{
    SCSIRequest *r;
    DPRINTF("Cancel tag=0x%x\n", tag);
    r = scsi_find_request(s, tag);
    if (r) {
        if (r->aiocb)
            bdrv_aio_cancel(r->aiocb);
        r->aiocb = NULL;
        scsi_remove_request(r);
    }
}

static void scsi_read_complete(void * opaque, int ret)
{
    SCSIRequest *r = (SCSIRequest *)opaque;
    SCSIDevice *s = r->dev;

    if (ret) {
        DPRINTF("IO error\n");
        scsi_command_complete(r, SENSE_HARDWARE_ERROR);
        return;
    }
    DPRINTF("Data ready tag=0x%x len=%d\n", r->tag, r->buf_len);

    s->completion(s->opaque, SCSI_REASON_DATA, r->tag, r->buf_len);
}

/* Read more data from scsi device into buffer.  */
void scsi_read_data(SCSIDevice *s, uint32_t tag)
{
    SCSIRequest *r;
    uint32_t n;

    r = scsi_find_request(s, tag);
    if (!r) {
        BADF("Bad read tag 0x%x\n", tag);
        /* ??? This is the wrong error.  */
        scsi_command_complete(r, SENSE_HARDWARE_ERROR);
        return;
    }
    if (r->sector_count == (uint32_t)-1) {
        DPRINTF("Read buf_len=%d\n", r->buf_len);
        r->sector_count = 0;
        s->completion(s->opaque, SCSI_REASON_DATA, r->tag, r->buf_len);
        return;
    }
    DPRINTF("Read sector_count=%d\n", r->sector_count);
    if (r->sector_count == 0) {
        scsi_command_complete(r, SENSE_NO_SENSE);
        return;
    }

    n = r->sector_count;
    if (n > SCSI_DMA_BUF_SIZE / 512)
        n = SCSI_DMA_BUF_SIZE / 512;

    r->buf_len = n * 512;
    r->aiocb = bdrv_aio_read(s->bdrv, r->sector, r->dma_buf, n,
                             scsi_read_complete, r);
    if (r->aiocb == NULL)
        scsi_command_complete(r, SENSE_HARDWARE_ERROR);
    r->sector += n;
    r->sector_count -= n;
}

static void scsi_write_complete(void * opaque, int ret)
{
    SCSIRequest *r = (SCSIRequest *)opaque;
    SCSIDevice *s = r->dev;
    uint32_t len;

    if (ret) {
        fprintf(stderr, "scsi-disc: IO write error\n");
        exit(1);
    }

    r->aiocb = NULL;
    if (r->sector_count == 0) {
        scsi_command_complete(r, SENSE_NO_SENSE);
    } else {
        len = r->sector_count * 512;
        if (len > SCSI_DMA_BUF_SIZE) {
            len = SCSI_DMA_BUF_SIZE;
        }
        r->buf_len = len;
        DPRINTF("Write complete tag=0x%x more=%d\n", r->tag, len);
        s->completion(s->opaque, SCSI_REASON_DATA, r->tag, len);
    }
}

/* Write data to a scsi device.  Returns nonzero on failure.
   The transfer may complete asynchronously.  */
int scsi_write_data(SCSIDevice *s, uint32_t tag)
{
    SCSIRequest *r;
    uint32_t n;

    DPRINTF("Write data tag=0x%x\n", tag);
    r = scsi_find_request(s, tag);
    if (!r) {
        BADF("Bad write tag 0x%x\n", tag);
        scsi_command_complete(r, SENSE_HARDWARE_ERROR);
        return 1;
    }
    if (r->aiocb)
        BADF("Data transfer already in progress\n");
    n = r->buf_len / 512;
    if (n) {
        r->aiocb = bdrv_aio_write(s->bdrv, r->sector, r->dma_buf, n,
                                  scsi_write_complete, r);
        if (r->aiocb == NULL)
            scsi_command_complete(r, SENSE_HARDWARE_ERROR);
        r->sector += n;
        r->sector_count -= n;
    } else {
        /* Invoke completion routine to fetch data from host.  */
        scsi_write_complete(r, 0);
    }

    return 0;
}

/* Return a pointer to the data buffer.  */
uint8_t *scsi_get_buf(SCSIDevice *s, uint32_t tag)
{
    SCSIRequest *r;

    r = scsi_find_request(s, tag);
    if (!r) {
        BADF("Bad buffer tag 0x%x\n", tag);
        return NULL;
    }
    return r->dma_buf;
}

/* 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.  */

int32_t scsi_send_command(SCSIDevice *s, uint32_t tag, uint8_t *buf, int lun)
{
    int64_t nb_sectors;
    uint32_t lba;
    uint32_t len;
    int cmdlen;
    int is_write;
    uint8_t command;
    uint8_t *outbuf;
    SCSIRequest *r;

    command = buf[0];
    r = scsi_find_request(s, tag);
    if (r) {
        BADF("Tag 0x%x already in use\n", tag);
        scsi_cancel_io(s, tag);
    }
    /* ??? Tags are not unique for different luns.  We only implement a
       single lun, so this should not matter.  */
    r = scsi_new_request(s, tag);
    outbuf = r->dma_buf;
    is_write = 0;
    DPRINTF("Command: lun=%d tag=0x%x data=0x%02x", lun, tag, buf[0]);
    switch (command >> 5) {
    case 0: