Implement PAPR virtual SCSI interface (ibmvscsi)

This patch implements the infrastructure and hypercalls necessary for
the PAPR specified Virtual SCSI interface.  This is the normal method
for providing (virtual) disks to PAPR partitions.

Signed-off-by: Ben Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 988 insertions, 0 deletions

diff --git a/hw/spapr_vscsi.c b/hw/spapr_vscsi.c
new file mode 100644
index 0000000000..e142dae624
--- /dev/null
+++ b/hw/spapr_vscsi.c
@@ -0,0 +1,988 @@
+/*
+ * QEMU PowerPC pSeries Logical Partition (aka sPAPR) hardware System Emulator
+ *
+ * PAPR Virtual SCSI, aka ibmvscsi
+ *
+ * Copyright (c) 2010,2011 Benjamin Herrenschmidt, IBM Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * TODO:
+ *
+ *  - Cleanups :-)
+ *  - Sort out better how to assign devices to VSCSI instances
+ *  - Fix residual counts
+ *  - Add indirect descriptors support
+ *  - Maybe do autosense (PAPR seems to mandate it, linux doesn't care)
+ */
+#include "hw.h"
+#include "scsi.h"
+#include "scsi-defs.h"
+#include "net.h" /* Remove that when we can */
+#include "srp.h"
+#include "hw/qdev.h"
+#include "hw/spapr.h"
+#include "hw/spapr_vio.h"
+#include "hw/ppc-viosrp.h"
+
+#include <libfdt.h>
+
+/*#define DEBUG_VSCSI*/
+
+#ifdef DEBUG_VSCSI
+#define dprintf(fmt, ...) \
+    do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)
+#else
+#define dprintf(fmt, ...) \
+    do { } while (0)
+#endif
+
+/*
+ * Virtual SCSI device
+ */
+
+/* Random numbers */
+#define VSCSI_MAX_SECTORS       4096
+#define VSCSI_REQ_LIMIT         24
+
+#define SCSI_SENSE_BUF_SIZE     96
+#define SRP_RSP_SENSE_DATA_LEN  18
+
+typedef union vscsi_crq {
+    struct viosrp_crq s;
+    uint8_t raw[16];
+} vscsi_crq;
+
+typedef struct vscsi_req {
+    vscsi_crq               crq;
+    union viosrp_iu         iu;
+
+    /* SCSI request tracking */
+    SCSIDevice              *sdev;
+    uint32_t                qtag; /* qemu tag != srp tag */
+    int                     lun;
+    int                     active;
+    long                    data_len;
+    int                     writing;
+    int                     sensing;
+    int                     senselen;
+    uint8_t                 sense[SCSI_SENSE_BUF_SIZE];
+
+    /* RDMA related bits */
+    uint8_t                 dma_fmt;
+    struct srp_direct_buf   ext_desc;
+    struct srp_direct_buf   *cur_desc;
+    struct srp_indirect_buf *ind_desc;
+    int                     local_desc;
+    int                     total_desc;
+} vscsi_req;
+
+
+typedef struct {
+    VIOsPAPRDevice vdev;
+    SCSIBus bus;
+    vscsi_req reqs[VSCSI_REQ_LIMIT];
+} VSCSIState;
+
+/* XXX Debug only */
+static VSCSIState *dbg_vscsi_state;
+
+
+static struct vscsi_req *vscsi_get_req(VSCSIState *s)
+{
+    vscsi_req *req;
+    int i;
+
+    for (i = 0; i < VSCSI_REQ_LIMIT; i++) {
+        req = &s->reqs[i];
+        if (!req->active) {
+            memset(req, 0, sizeof(*req));
+            req->qtag = i;
+            req->active = 1;
+            return req;
+        }
+    }
+    return NULL;
+}
+
+static void vscsi_put_req(VSCSIState *s, vscsi_req *req)
+{
+    req->active = 0;
+}
+
+static vscsi_req *vscsi_find_req(VSCSIState *s, uint32_t tag)
+{
+    if (tag >= VSCSI_REQ_LIMIT || !s->reqs[tag].active) {
+        return NULL;
+    }
+    return &s->reqs[tag];
+}
+
+static void vscsi_decode_id_lun(uint64_t srp_lun, int *id, int *lun)
+{
+    /* XXX Figure that one out properly ! This is crackpot */
+    *id = (srp_lun >> 56) & 0x7f;
+    *lun = (srp_lun >> 48) & 0xff;
+}
+
+static int vscsi_send_iu(VSCSIState *s, vscsi_req *req,
+                         uint64_t length, uint8_t format)
+{
+    long rc, rc1;
+
+    /* First copy the SRP */
+    rc = spapr_tce_dma_write(&s->vdev, req->crq.s.IU_data_ptr,
+                             &req->iu, length);
+    if (rc) {
+        fprintf(stderr, "vscsi_send_iu: DMA write failure !\n");
+    }
+
+    req->crq.s.valid = 0x80;
+    req->crq.s.format = format;
+    req->crq.s.reserved = 0x00;
+    req->crq.s.timeout = cpu_to_be16(0x0000);
+    req->crq.s.IU_length = cpu_to_be16(length);
+    req->crq.s.IU_data_ptr = req->iu.srp.rsp.tag; /* right byte order */
+
+    if (rc == 0) {
+        req->crq.s.status = 0x99; /* Just needs to be non-zero */
+    } else {
+        req->crq.s.status = 0x00;
+    }
+
+    rc1 = spapr_vio_send_crq(&s->vdev, req->crq.raw);
+    if (rc1) {
+        fprintf(stderr, "vscsi_send_iu: Error sending response\n");
+        return rc1;
+    }
+
+    return rc;
+}
+
+static void vscsi_makeup_sense(VSCSIState *s, vscsi_req *req,
+                               uint8_t key, uint8_t asc, uint8_t ascq)
+{
+    req->senselen = SRP_RSP_SENSE_DATA_LEN;
+
+    /* Valid bit and 'current errors' */
+    req->sense[0] = (0x1 << 7 | 0x70);
+    /* Sense key */
+    req->sense[2] = key;
+    /* Additional sense length */
+    req->sense[7] = 0xa; /* 10 bytes */
+    /* Additional sense code */
+    req->sense[12] = asc;
+    req->sense[13] = ascq;
+}
+
+static int vscsi_send_rsp(VSCSIState *s, vscsi_req *req,
+                          uint8_t status, int32_t res_in, int32_t res_out)
+{
+    union viosrp_iu *iu = &req->iu;
+    uint64_t tag = iu->srp.rsp.tag;
+    int total_len = sizeof(iu->srp.rsp);
+
+    dprintf("VSCSI: Sending resp status: 0x%x, "
+            "res_in: %d, res_out: %d\n", status, res_in, res_out);
+
+    memset(iu, 0, sizeof(struct srp_rsp));
+    iu->srp.rsp.opcode = SRP_RSP;
+    iu->srp.rsp.req_lim_delta = cpu_to_be32(1);
+    iu->srp.rsp.tag = tag;
+
+    /* Handle residuals */
+    if (res_in < 0) {
+        iu->srp.rsp.flags |= SRP_RSP_FLAG_DIUNDER;
+        res_in = -res_in;
+    } else if (res_in) {
+        iu->srp.rsp.flags |= SRP_RSP_FLAG_DIOVER;
+    }
+    if (res_out < 0) {
+        iu->srp.rsp.flags |= SRP_RSP_FLAG_DOUNDER;
+        res_out = -res_out;
+    } else if (res_out) {
+        iu->srp.rsp.flags |= SRP_RSP_FLAG_DOOVER;
+    }
+    iu->srp.rsp.data_in_res_cnt = cpu_to_be32(res_in);
+    iu->srp.rsp.data_out_res_cnt = cpu_to_be32(res_out);
+
+    /* We don't do response data */
+    /* iu->srp.rsp.flags &= ~SRP_RSP_FLAG_RSPVALID; */
+    iu->srp.rsp.resp_data_len = cpu_to_be32(0);
+
+    /* Handle success vs. failure */
+    iu->srp.rsp.status = status;
+    if (status) {
+        iu->srp.rsp.sol_not = (iu->srp.cmd.sol_not & 0x04) >> 2;
+        if (req->senselen) {
+            req->iu.srp.rsp.flags |= SRP_RSP_FLAG_SNSVALID;
+            req->iu.srp.rsp.sense_data_len = cpu_to_be32(req->senselen);
+            memcpy(req->iu.srp.rsp.data, req->sense, req->senselen);
+            total_len += req->senselen;
+        }
+    } else {
+        iu->srp.rsp.sol_not = (iu->srp.cmd.sol_not & 0x02) >> 1;
+    }
+
+    vscsi_send_iu(s, req, total_len, VIOSRP_SRP_FORMAT);
+    return 0;
+}
+
+static inline void vscsi_swap_desc(struct srp_direct_buf *desc)
+{
+    desc->va = be64_to_cpu(desc->va);
+    desc->len = be32_to_cpu(desc->len);
+}
+
+static int vscsi_srp_direct_data(VSCSIState *s, vscsi_req *req,
+                                 uint8_t *buf, uint32_t len)
+{
+    struct srp_direct_buf *md = req->cur_desc;
+    uint32_t llen;
+    int rc;
+
+    dprintf("VSCSI: direct segment 0x%x bytes, va=0x%llx desc len=0x%x\n",
+            len, (unsigned long long)md->va, md->len);
+
+    llen = MIN(len, md->len);
+    if (llen) {
+        if (req->writing) { /* writing = to device = reading from memory */
+            rc = spapr_tce_dma_read(&s->vdev, md->va, buf, llen);
+        } else {
+            rc = spapr_tce_dma_write(&s->vdev, md->va, buf, llen);
+        }
+    }
+    md->len -= llen;
+    md->va += llen;
+
+    if (rc) {
+        return -1;
+    }
+    return llen;
+}
+
+static int vscsi_srp_indirect_data(VSCSIState *s, vscsi_req *req,
+                                   uint8_t *buf, uint32_t len)
+{
+    struct srp_direct_buf *td = &req->ind_desc->table_desc;
+    struct srp_direct_buf *md = req->cur_desc;
+    int rc = 0;
+    uint32_t llen, total = 0;
+
+    dprintf("VSCSI: indirect segment 0x%x bytes, td va=0x%llx len=0x%x\n",
+            len, (unsigned long long)td->va, td->len);
+
+    /* While we have data ... */
+    while (len) {
+        /* If we have a descriptor but it's empty, go fetch a new one */
+        if (md && md->len == 0) {
+            /* More local available, use one */
+            if (req->local_desc) {
+                md = ++req->cur_desc;
+                --req->local_desc;
+                --req->total_desc;
+                td->va += sizeof(struct srp_direct_buf);
+            } else {
+                md = req->cur_desc = NULL;
+            }
+        }
+        /* No descriptor at hand, fetch one */
+        if (!md) {
+            if (!req->total_desc) {
+                dprintf("VSCSI:   Out of descriptors !\n");
+                break;
+            }
+            md = req->cur_desc = &req->ext_desc;
+            dprintf("VSCSI:   Reading desc from 0x%llx\n",
+                    (unsigned long long)td->va);
+            rc = spapr_tce_dma_read(&s->vdev, td->va, md,
+                                    sizeof(struct srp_direct_buf));
+            if (rc) {
+                dprintf("VSCSI: tce_dma_read -> %d reading ext_desc\n", rc);
+                break;
+            }
+            vscsi_swap_desc(md);
+            td->va += sizeof(struct srp_direct_buf);
+            --req->total_desc;
+        }
+        dprintf("VSCSI:   [desc va=0x%llx,len=0x%x] remaining=0x%x\n",
+                (unsigned long long)md->va, md->len, len);
+
+        /* Perform transfer */
+        llen = MIN(len, md->len);
+        if (req->writing) { /* writing = to device = reading from memory */
+            rc = spapr_tce_dma_read(&s->vdev, md->va, buf, llen);
+        } else {
+            rc = spapr_tce_dma_write(&s->vdev, md->va, buf, llen);
+        }
+        if (rc) {
+            dprintf("VSCSI: tce_dma_r/w(%d) -> %d\n", req->writing, rc);
+            break;
+        }
+        dprintf("VSCSI:     data: %02x %02x %02x %02x...\n",
+                buf[0], buf[1], buf[2], buf[3]);
+
+        len -= llen;
+        buf += llen;
+        total += llen;
+        md->va += llen;
+        md->len -= llen;
+    }
+    return rc ? -1 : total;
+}
+
+static int vscsi_srp_transfer_data(VSCSIState *s, vscsi_req *req,
+                                   int writing, uint8_t *buf, uint32_t len)
+{
+    int err = 0;
+
+    switch (req->dma_fmt) {
+    case SRP_NO_DATA_DESC:
+        dprintf("VSCSI: no data desc transfer, skipping 0x%x bytes\n", len);
+        break;
+    case SRP_DATA_DESC_DIRECT:
+        err = vscsi_srp_direct_data(s, req, buf, len);
+        break;
+    case SRP_DATA_DESC_INDIRECT:
+        err = vscsi_srp_indirect_data(s, req, buf, len);
+        break;
+    }
+    return err;
+}
+
+/* Bits from linux srp */
+static int data_out_desc_size(struct srp_cmd *cmd)
+{
+    int size = 0;
+    uint8_t fmt = cmd->buf_fmt >> 4;
+
+    switch (fmt) {
+    case SRP_NO_DATA_DESC:
+        break;
+    case SRP_DATA_DESC_DIRECT:
+        size = sizeof(struct srp_direct_buf);
+        break;
+    case SRP_DATA_DESC_INDIRECT:
+        size = sizeof(struct srp_indirect_buf) +
+            sizeof(struct srp_direct_buf)*cmd->data_out_desc_cnt;
+        break;
+    default:
+        break;
+    }
+    return size;
+}
+
+static int vscsi_preprocess_desc(vscsi_req *req)
+{
+    struct srp_cmd *cmd = &req->iu.srp.cmd;
+    int offset, i;
+
+    offset = cmd->add_cdb_len & ~3;
+
+    if (req->writing) {
+        req->dma_fmt = cmd->buf_fmt >> 4;
+    } else {
+        offset += data_out_desc_size(cmd);
+        req->dma_fmt = cmd->buf_fmt & ((1U << 4) - 1);
+    }
+
+    switch (req->dma_fmt) {
+    case SRP_NO_DATA_DESC:
+        break;
+    case SRP_DATA_DESC_DIRECT:
+        req->cur_desc = (struct srp_direct_buf *)(cmd->add_data + offset);
+        req->total_desc = req->local_desc = 1;
+        vscsi_swap_desc(req->cur_desc);
+        dprintf("VSCSI: using direct RDMA %s, 0x%x bytes MD: 0x%llx\n",
+                req->writing ? "write" : "read",
+                req->cur_desc->len, (unsigned long long)req->cur_desc->va);
+        break;
+    case SRP_DATA_DESC_INDIRECT:
+        req->ind_desc = (struct srp_indirect_buf *)(cmd->add_data + offset);
+        vscsi_swap_desc(&req->ind_desc->table_desc);
+        req->total_desc = req->ind_desc->table_desc.len /
+            sizeof(struct srp_direct_buf);
+        req->local_desc = req->writing ? cmd->data_out_desc_cnt :
+            cmd->data_in_desc_cnt;
+        for (i = 0; i < req->local_desc; i++) {
+            vscsi_swap_desc(&req->ind_desc->desc_list[i]);
+        }
+        req->cur_desc = req->local_desc ? &req->ind_desc->desc_list[0] : NULL;
+        dprintf("VSCSI: using indirect RDMA %s, 0x%x bytes %d descs "
+                "(%d local) VA: 0x%llx\n",
+                req->writing ? "read" : "write",
+                be32_to_cpu(req->ind_desc->len),
+                req->total_desc, req->local_desc,
+                (unsigned long long)req->ind_desc->table_desc.va);
+        break;
+    default:
+        fprintf(stderr,
+                "vscsi_preprocess_desc: Unknown format %x\n", req->dma_fmt);
+        return -1;
+    }
+
+    return 0;
+}
+
+static void vscsi_send_request_sense(VSCSIState *s, vscsi_req *req)
+{
+    SCSIDevice *sdev = req->sdev;
+    uint8_t *cdb = req->iu.srp.cmd.cdb;
+    int n;
+
+    cdb[0] = 3;
+    cdb[1] = 0;
+    cdb[2] = 0;
+    cdb[3] = 0;
+    cdb[4] = 96;
+    cdb[5] = 0;
+    req->sensing = 1;
+    n = sdev->info->send_command(sdev, req->qtag, cdb, req->lun);
+    dprintf("VSCSI: Queued request sense tag 0x%x\n", req->qtag);
+    if (n < 0) {
+        fprintf(stderr, "VSCSI: REQUEST_SENSE wants write data !?!?!?\n");
+        sdev->info->cancel_io(sdev, req->qtag);
+        vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0);
+        vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
+        vscsi_put_req(s, req);
+        return;
+    } else if (n == 0) {
+        return;
+    }
+    sdev->info->read_data(sdev, req->qtag);
+}
+
+/* Callback to indicate that the SCSI layer has completed a transfer.  */
+static void vscsi_command_complete(SCSIBus *bus, int reason, uint32_t tag,
+                                   uint32_t arg)
+{
+    VSCSIState *s = DO_UPCAST(VSCSIState, vdev.qdev, bus->qbus.parent);
+    vscsi_req *req = vscsi_find_req(s, tag);
+    SCSIDevice *sdev;
+    uint8_t *buf;
+    int32_t res_in = 0, res_out = 0;
+    int len, rc = 0;
+
+    dprintf("VSCSI: SCSI cmd complete, r=0x%x tag=0x%x arg=0x%x, req=%p\n",
+            reason, tag, arg, req);
+    if (req == NULL) {
+        fprintf(stderr, "VSCSI: Can't find request for tag 0x%x\n", tag);
+        return;
+    }
+    sdev = req->sdev;
+
+    if (req->sensing) {
+        if (reason == SCSI_REASON_DONE) {
+            dprintf("VSCSI: Sense done !\n");
+            vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
+            vscsi_put_req(s, req);
+        } else {
+            uint8_t *buf = sdev->info->get_buf(sdev, tag);
+
+            len = MIN(arg, SCSI_SENSE_BUF_SIZE);
+            dprintf("VSCSI: Sense data, %d bytes:\n", len);
+            dprintf("       %02x  %02x  %02x  %02x  %02x  %02x  %02x  %02x\n",
+                    buf[0], buf[1], buf[2], buf[3],
+                    buf[4], buf[5], buf[6], buf[7]);
+            dprintf("       %02x  %02x  %02x  %02x  %02x  %02x  %02x  %02x\n",
+                    buf[8], buf[9], buf[10], buf[11],
+                    buf[12], buf[13], buf[14], buf[15]);
+            memcpy(req->sense, buf, len);
+            req->senselen = len;
+            sdev->info->read_data(sdev, req->qtag);
+        }
+        return;
+    }
+
+    if (reason == SCSI_REASON_DONE) {
+        dprintf("VSCSI: Command complete err=%d\n", arg);
+        if (arg == 0) {
+            /* We handle overflows, not underflows for normal commands,
+             * but hopefully nobody cares
+             */
+            if (req->writing) {
+                res_out = req->data_len;
+            } else {
+                res_in = req->data_len;
+            }
+            vscsi_send_rsp(s, req, 0, res_in, res_out);
+        } else if (arg == CHECK_CONDITION) {
+            dprintf("VSCSI: Got CHECK_CONDITION, requesting sense...\n");
+            vscsi_send_request_sense(s, req);
+            return;
+        } else {
+            vscsi_send_rsp(s, req, arg, 0, 0);
+        }
+        vscsi_put_req(s, req);
+        return;
+    }
+
+    /* "arg" is how much we have read for reads and how much we want
+     * to write for writes (ie, how much is to be DMA'd)
+     */
+    if (arg) {
+        buf = sdev->info->get_buf(sdev, tag);
+        rc = vscsi_srp_transfer_data(s, req, req->writing, buf, arg);
+    }
+    if (rc < 0) {
+        fprintf(stderr, "VSCSI: RDMA error rc=%d!\n", rc);
+        sdev->info->cancel_io(sdev, req->qtag);
+        vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0);
+        vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
+        vscsi_put_req(s, req);
+        return;
+    }
+
+    /* Start next chunk */
+    req->data_len -= rc;
+    if (req->writing) {
+        sdev->info->write_data(sdev, req->qtag);
+    } else {
+        sdev->info->read_data(sdev, req->qtag);
+    }
+}
+
+static void vscsi_process_login(VSCSIState *s, vscsi_req *req)
+{
+    union viosrp_iu *iu = &req->iu;
+    struct srp_login_rsp *rsp = &iu->srp.login_rsp;
+    uint64_t tag = iu->srp.rsp.tag;
+
+    dprintf("VSCSI: Got login, sendin response !\n");
+
+    /* TODO handle case that requested size is wrong and
+     * buffer format is wrong
+     */
+    memset(iu, 0, sizeof(struct srp_login_rsp));
+    rsp->opcode = SRP_LOGIN_RSP;
+    /* Don't advertise quite as many request as we support to
+     * keep room for management stuff etc...
+     */
+    rsp->req_lim_delta = cpu_to_be32(VSCSI_REQ_LIMIT-2);
+    rsp->tag = tag;
+    rsp->max_it_iu_len = cpu_to_be32(sizeof(union srp_iu));
+    rsp->max_ti_iu_len = cpu_to_be32(sizeof(union srp_iu));
+    /* direct and indirect */
+    rsp->buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT | SRP_BUF_FORMAT_INDIRECT);
+
+    vscsi_send_iu(s, req, sizeof(*rsp), VIOSRP_SRP_FORMAT);
+}
+
+static void vscsi_inquiry_no_target(VSCSIState *s, vscsi_req *req)
+{
+    uint8_t *cdb = req->iu.srp.cmd.cdb;
+    uint8_t resp_data[36];
+    int rc, len, alen;
+
+    /* We dont do EVPD. Also check that page_code is 0 */
+    if ((cdb[1] & 0x01) || (cdb[1] & 0x01) || cdb[2] != 0) {
+        /* Send INVALID FIELD IN CDB */
+        vscsi_makeup_sense(s, req, ILLEGAL_REQUEST, 0x24, 0);
+        vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
+        return;
+    }
+    alen = cdb[3];
+    alen = (alen << 8) | cdb[4];
+    len = MIN(alen, 36);
+
+    /* Fake up inquiry using PQ=3 */
+    memset(resp_data, 0, 36);
+    resp_data[0] = 0x7f;   /* Not capable of supporting a device here */
+    resp_data[2] = 0x06;   /* SPS-4 */
+    resp_data[3] = 0x02;   /* Resp data format */
+    resp_data[4] = 36 - 5; /* Additional length */
+    resp_data[7] = 0x10;   /* Sync transfers */
+    memcpy(&resp_data[16], "QEMU EMPTY      ", 16);
+    memcpy(&resp_data[8], "QEMU    ", 8);
+
+    req->writing = 0;
+    vscsi_preprocess_desc(req);
+    rc = vscsi_srp_transfer_data(s, req, 0, resp_data, len);
+    if (rc < 0) {
+        vscsi_makeup_sense(s, req, HARDWARE_ERROR, 0, 0);
+        vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
+    } else {
+        vscsi_send_rsp(s, req, 0, 36 - rc, 0);
+    }
+}
+
+static int vscsi_queue_cmd(VSCSIState *s, vscsi_req *req)
+{
+    union srp_iu *srp = &req->iu.srp;
+    SCSIDevice *sdev;
+    int n, id, lun;
+
+    vscsi_decode_id_lun(be64_to_cpu(srp->cmd.lun), &id, &lun);
+
+    /* Qemu vs. linux issue with LUNs to be sorted out ... */
+    sdev = (id < 8 && lun < 16) ? s->bus.devs[id] : NULL;
+    if (!sdev) {
+        dprintf("VSCSI: Command for id %d with no drive\n", id);
+        if (srp->cmd.cdb[0] == INQUIRY) {
+            vscsi_inquiry_no_target(s, req);
+        } else {
+            vscsi_makeup_sense(s, req, ILLEGAL_REQUEST, 0x24, 0x00);
+            vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
+        } return 1;
+    }
+
+    req->sdev = sdev;
+    req->lun = lun;
+    n = sdev->info->send_command(sdev, req->qtag, srp->cmd.cdb, lun);
+
+    dprintf("VSCSI: Queued command tag 0x%x CMD 0x%x ID %d LUN %d ret: %d\n",
+            req->qtag, srp->cmd.cdb[0], id, lun, n);
+
+    if (n) {
+        /* Transfer direction must be set before preprocessing the
+         * descriptors
+         */
+        req->writing = (n < 1);
+
+        /* Preprocess RDMA descriptors */
+        vscsi_preprocess_desc(req);
+    }
+
+    /* Get transfer direction and initiate transfer */
+    if (n > 0) {
+        req->data_len = n;
+        sdev->info->read_data(sdev, req->qtag);
+    } else if (n < 0) {
+        req->data_len = -n;
+        sdev->info->write_data(sdev, req->qtag);
+    }
+    /* Don't touch req here, it may have been recycled already */
+
+    return 0;
+}
+
+static int vscsi_process_tsk_mgmt(VSCSIState *s, vscsi_req *req)
+{
+    union viosrp_iu *iu = &req->iu;
+    int fn;
+
+    fprintf(stderr, "vscsi_process_tsk_mgmt %02x\n",
+            iu->srp.tsk_mgmt.tsk_mgmt_func);
+
+    switch (iu->srp.tsk_mgmt.tsk_mgmt_func) {
+#if 0 /* We really don't deal with these for now */
+    case SRP_TSK_ABORT_TASK:
+        fn = ABORT_TASK;
+        break;
+    case SRP_TSK_ABORT_TASK_SET:
+        fn = ABORT_TASK_SET;
+        break;
+    case SRP_TSK_CLEAR_TASK_SET:
+        fn = CLEAR_TASK_SET;
+        break;
+    case SRP_TSK_LUN_RESET:
+        fn = LOGICAL_UNIT_RESET;
+        break;
+    case SRP_TSK_CLEAR_ACA:
+        fn = CLEAR_ACA;
+        break;
+#endif
+    default:
+        fn = 0;
+    }
+    if (fn) {
+        /* XXX Send/Handle target task management */
+        ;
+    } else {
+        vscsi_makeup_sense(s, req, ILLEGAL_REQUEST, 0x20, 0);
+        vscsi_send_rsp(s, req, CHECK_CONDITION, 0, 0);
+    }
+    return !fn;
+}
+
+static int vscsi_handle_srp_req(VSCSIState *s, vscsi_req *req)
+{
+    union srp_iu *srp = &req->iu.srp;
+    int done = 1;
+    uint8_t opcode = srp->rsp.opcode;
+
+    switch (opcode) {
+    case SRP_LOGIN_REQ:
+        vscsi_process_login(s, req);
+        break;
+    case SRP_TSK_MGMT:
+        done = vscsi_process_tsk_mgmt(s, req);
+        break;
+    case SRP_CMD:
+        done = vscsi_queue_cmd(s, req);
+        break;
+    case SRP_LOGIN_RSP:
+    case SRP_I_LOGOUT:
+    case SRP_T_LOGOUT:
+    case SRP_RSP:
+    case SRP_CRED_REQ:
+    case SRP_CRED_RSP:
+    case SRP_AER_REQ:
+    case SRP_AER_RSP:
+        fprintf(stderr, "VSCSI: Unsupported opcode %02x\n", opcode);
+        break;
+    default:
+        fprintf(stderr, "VSCSI: Unknown type %02x\n", opcode);
+    }
+
+    return done;
+}
+
+static int vscsi_send_adapter_info(VSCSIState *s, vscsi_req *req)
+{
+    struct viosrp_adapter_info *sinfo;
+    struct mad_adapter_info_data info;
+    int rc;
+
+    sinfo = &req->iu.mad.adapter_info;
+
+#if 0 /* What for ? */
+    rc = spapr_tce_dma_read(&s->vdev, be64_to_cpu(sinfo->buffer),
+                            &info, be16_to_cpu(sinfo->common.length));
+    if (rc) {
+        fprintf(stderr, "vscsi_send_adapter_info: DMA read failure !\n");
+    }
+#endif
+    memset(&info, 0, sizeof(info));
+    strcpy(info.srp_version, SRP_VERSION);
+    strncpy(info.partition_name, "qemu", sizeof("qemu"));
+    info.partition_number = cpu_to_be32(0);
+    info.mad_version = cpu_to_be32(1);
+    info.os_type = cpu_to_be32(2);
+    info.port_max_txu[0] = cpu_to_be32(VSCSI_MAX_SECTORS << 9);
+
+    rc = spapr_tce_dma_write(&s->vdev, be64_to_cpu(sinfo->buffer),
+                             &info, be16_to_cpu(sinfo->common.length));
+    if (rc)  {
+        fprintf(stderr, "vscsi_send_adapter_info: DMA write failure !\n");
+    }
+
+    sinfo->common.status = rc ? cpu_to_be32(1) : 0;
+
+    return vscsi_send_iu(s, req, sizeof(*sinfo), VIOSRP_MAD_FORMAT);
+}
+
+static int vscsi_handle_mad_req(VSCSIState *s, vscsi_req *req)
+{
+    union mad_iu *mad = &req->iu.mad;
+
+    switch (be32_to_cpu(mad->empty_iu.common.type)) {
+    case VIOSRP_EMPTY_IU_TYPE:
+        fprintf(stderr, "Unsupported EMPTY MAD IU\n");
+        break;
+    case VIOSRP_ERROR_LOG_TYPE:
+        fprintf(stderr, "Unsupported ERROR LOG MAD IU\n");
+        mad->error_log.common.status = cpu_to_be16(1);
+        vscsi_send_iu(s, req, sizeof(mad->error_log), VIOSRP_MAD_FORMAT);
+        break;
+    case VIOSRP_ADAPTER_INFO_TYPE:
+        vscsi_send_adapter_info(s, req);
+        break;
+    case VIOSRP_HOST_CONFIG_TYPE:
+        mad->host_config.common.status = cpu_to_be16(1);
+        vscsi_send_iu(s, req, sizeof(mad->host_config), VIOSRP_MAD_FORMAT);
+        break;
+    default:
+        fprintf(stderr, "VSCSI: Unknown MAD type %02x\n",
+                be32_to_cpu(mad->empty_iu.common.type));
+    }
+
+    return 1;
+}
+
+static void vscsi_got_payload(VSCSIState *s, vscsi_crq *crq)
+{
+    vscsi_req *req;
+    int done;
+
+    req = vscsi_get_req(s);
+    if (req == NULL) {
+        fprintf(stderr, "VSCSI: Failed to get a request !\n");
+        return;
+    }
+
+    /* We only support a limited number of descriptors, we know
+     * the ibmvscsi driver uses up to 10 max, so it should fit
+     * in our 256 bytes IUs. If not we'll have to increase the size
+     * of the structure.
+     */
+    if (crq->s.IU_length > sizeof(union viosrp_iu)) {
+        fprintf(stderr, "VSCSI: SRP IU too long (%d bytes) !\n",
+                crq->s.IU_length);
+        return;
+    }
+
+    /* XXX Handle failure differently ? */
+    if (spapr_tce_dma_read(&s->vdev, crq->s.IU_data_ptr, &req->iu,
+                           crq->s.IU_length)) {
+        fprintf(stderr, "vscsi_got_payload: DMA read failure !\n");
+        qemu_free(req);
+    }
+    memcpy(&req->crq, crq, sizeof(vscsi_crq));
+
+    if (crq->s.format == VIOSRP_MAD_FORMAT) {
+        done = vscsi_handle_mad_req(s, req);
+    } else {
+        done = vscsi_handle_srp_req(s, req);
+    }
+
+    if (done) {
+        vscsi_put_req(s, req);
+    }
+}
+
+
+static int vscsi_do_crq(struct VIOsPAPRDevice *dev, uint8_t *crq_data)
+{
+    VSCSIState *s = DO_UPCAST(VSCSIState, vdev, dev);
+    vscsi_crq crq;
+
+    memcpy(crq.raw, crq_data, 16);
+    crq.s.timeout = be16_to_cpu(crq.s.timeout);
+    crq.s.IU_length = be16_to_cpu(crq.s.IU_length);
+    crq.s.IU_data_ptr = be64_to_cpu(crq.s.IU_data_ptr);
+
+    dprintf("VSCSI: do_crq %02x %02x ...\n", crq.raw[0], crq.raw[1]);
+
+    switch (crq.s.valid) {
+    case 0xc0: /* Init command/response */
+
+        /* Respond to initialization request */
+        if (crq.s.format == 0x01) {
+            memset(crq.raw, 0, 16);
+            crq.s.valid = 0xc0;
+            crq.s.format = 0x02;
+            spapr_vio_send_crq(dev, crq.raw);
+        }
+
+        /* Note that in hotplug cases, we might get a 0x02
+         * as a result of us emitting the init request
+         */
+
+        break;
+    case 0xff: /* Link event */
+
+        /* Not handled for now */
+
+        break;
+    case 0x80: /* Payloads */
+        switch (crq.s.format) {
+        case VIOSRP_SRP_FORMAT: /* AKA VSCSI request */
+        case VIOSRP_MAD_FORMAT: /* AKA VSCSI response */
+            vscsi_got_payload(s, &crq);
+            break;
+        case VIOSRP_OS400_FORMAT:
+        case VIOSRP_AIX_FORMAT:
+        case VIOSRP_LINUX_FORMAT:
+        case VIOSRP_INLINE_FORMAT:
+            fprintf(stderr, "vscsi_do_srq: Unsupported payload format %02x\n",
+                    crq.s.format);
+            break;
+        default:
+            fprintf(stderr, "vscsi_do_srq: Unknown payload format %02x\n",
+                    crq.s.format);
+        }
+        break;
+    default:
+        fprintf(stderr, "vscsi_do_crq: unknown CRQ %02x %02x ...\n",
+                crq.raw[0], crq.raw[1]);
+    };
+
+    return 0;
+}
+
+static int spapr_vscsi_init(VIOsPAPRDevice *dev)
+{
+    VSCSIState *s = DO_UPCAST(VSCSIState, vdev, dev);
+    int i;
+
+    dbg_vscsi_state = s;
+
+    /* Initialize qemu request tags */
+    memset(s->reqs, 0, sizeof(s->reqs));
+    for (i = 0; i < VSCSI_REQ_LIMIT; i++) {
+        s->reqs[i].qtag = i;
+    }
+
+    dev->crq.SendFunc = vscsi_do_crq;
+
+    scsi_bus_new(&s->bus, &dev->qdev, 1, VSCSI_REQ_LIMIT,
+                 vscsi_command_complete);
+    if (!dev->qdev.hotplugged) {
+        scsi_bus_legacy_handle_cmdline(&s->bus);
+    }
+
+    return 0;
+}
+
+void spapr_vscsi_create(VIOsPAPRBus *bus, uint32_t reg,
+                        qemu_irq qirq, uint32_t vio_irq_num)
+{
+    DeviceState *dev;
+    VIOsPAPRDevice *sdev;
+
+    dev = qdev_create(&bus->bus, "spapr-vscsi");
+    qdev_prop_set_uint32(dev, "reg", reg);
+
+    qdev_init_nofail(dev);
+
+    sdev = (VIOsPAPRDevice *)dev;
+    sdev->qirq = qirq;
+    sdev->vio_irq_num = vio_irq_num;
+}
+
+static int spapr_vscsi_devnode(VIOsPAPRDevice *dev, void *fdt, int node_off)
+{
+    int ret;
+
+    ret = fdt_setprop_cell(fdt, node_off, "#address-cells", 2);
+    if (ret < 0) {
+        return ret;
+    }
+
+    ret = fdt_setprop_cell(fdt, node_off, "#size-cells", 0);
+    if (ret < 0) {
+        return ret;
+    }
+
+    return 0;
+}
+
+static VIOsPAPRDeviceInfo spapr_vscsi = {
+    .init = spapr_vscsi_init,
+    .devnode = spapr_vscsi_devnode,
+    .dt_name = "v-scsi",
+    .dt_type = "vscsi",
+    .dt_compatible = "IBM,v-scsi",
+    .signal_mask = 0x00000001,
+    .qdev.name = "spapr-vscsi",
+    .qdev.size = sizeof(VSCSIState),
+    .qdev.props = (Property[]) {
+        DEFINE_PROP_UINT32("reg", VIOsPAPRDevice, reg, 0x2000),
+        DEFINE_PROP_UINT32("dma-window", VIOsPAPRDevice,
+                           rtce_window_size, 0x10000000),
+        DEFINE_PROP_END_OF_LIST(),
+    },
+};
+
+static void spapr_vscsi_register(void)
+{
+    spapr_vio_bus_register_withprop(&spapr_vscsi);
+}
+device_init(spapr_vscsi_register);