storvsc_drv.c

Go to the documentation of this file.

/*
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <[email protected]>
 *   Hank Janssen  <[email protected]>
 *   K. Y. Srinivasan <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/hyperv.h>
#include <linux/mempool.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_devinfo.h>
#include <scsi/scsi_dbg.h>

/*
 * All wire protocol details (storage protocol between the guest and the host)
 * are consolidated here.
 *
 * Begin protocol definitions.
 */

/*
 * Version history:
 * V1 Beta: 0.1
 * V1 RC < 2008/1/31: 1.0
 * V1 RC > 2008/1/31:  2.0
 * Win7: 4.2
 */

#define VMSTOR_CURRENT_MAJOR  4
#define VMSTOR_CURRENT_MINOR  2


/*  Packet structure describing virtual storage requests. */
enum vstor_packet_operation {
    VSTOR_OPERATION_COMPLETE_IO     = 1,
    VSTOR_OPERATION_REMOVE_DEVICE       = 2,
    VSTOR_OPERATION_EXECUTE_SRB     = 3,
    VSTOR_OPERATION_RESET_LUN       = 4,
    VSTOR_OPERATION_RESET_ADAPTER       = 5,
    VSTOR_OPERATION_RESET_BUS       = 6,
    VSTOR_OPERATION_BEGIN_INITIALIZATION    = 7,
    VSTOR_OPERATION_END_INITIALIZATION  = 8,
    VSTOR_OPERATION_QUERY_PROTOCOL_VERSION  = 9,
    VSTOR_OPERATION_QUERY_PROPERTIES    = 10,
    VSTOR_OPERATION_ENUMERATE_BUS       = 11,
    VSTOR_OPERATION_MAXIMUM         = 11
};

/*
 * Platform neutral description of a scsi request -
 * this remains the same across the write regardless of 32/64 bit
 * note: it's patterned off the SCSI_PASS_THROUGH structure
 */
#define STORVSC_MAX_CMD_LEN         0x10
#define STORVSC_SENSE_BUFFER_SIZE       0x12
#define STORVSC_MAX_BUF_LEN_WITH_PADDING    0x14

struct vmscsi_request {
    u16 length;
    u8 srb_status;
    u8 scsi_status;

    u8  port_number;
    u8  path_id;
    u8  target_id;
    u8  lun;

    u8  cdb_length;
    u8  sense_info_length;
    u8  data_in;
    u8  reserved;

    u32 data_transfer_length;

    union {
        u8 cdb[STORVSC_MAX_CMD_LEN];
        u8 sense_data[STORVSC_SENSE_BUFFER_SIZE];
        u8 reserved_array[STORVSC_MAX_BUF_LEN_WITH_PADDING];
    };
} __attribute((packed));


/*
 * This structure is sent during the intialization phase to get the different
 * properties of the channel.
 */
struct vmstorage_channel_properties {
    u16 protocol_version;
    u8  path_id;
    u8 target_id;

    /* Note: port number is only really known on the client side */
    u32  port_number;
    u32  flags;
    u32   max_transfer_bytes;

    /*
     * This id is unique for each channel and will correspond with
     * vendor specific data in the inquiry data.
     */

    u64  unique_id;
} __packed;

/*  This structure is sent during the storage protocol negotiations. */
struct vmstorage_protocol_version {
    /* Major (MSW) and minor (LSW) version numbers. */
    u16 major_minor;

    /*
     * Revision number is auto-incremented whenever this file is changed
     * (See FILL_VMSTOR_REVISION macro above).  Mismatch does not
     * definitely indicate incompatibility--but it does indicate mismatched
     * builds.
     * This is only used on the windows side. Just set it to 0.
     */
    u16 revision;
} __packed;

/* Channel Property Flags */
#define STORAGE_CHANNEL_REMOVABLE_FLAG      0x1
#define STORAGE_CHANNEL_EMULATED_IDE_FLAG   0x2

struct vstor_packet {
    /* Requested operation type */
    enum vstor_packet_operation operation;

    /*  Flags - see below for values */
    u32 flags;

    /* Status of the request returned from the server side. */
    u32 status;

    /* Data payload area */
    union {
        /*
         * Structure used to forward SCSI commands from the
         * client to the server.
         */
        struct vmscsi_request vm_srb;

        /* Structure used to query channel properties. */
        struct vmstorage_channel_properties storage_channel_properties;

        /* Used during version negotiations. */
        struct vmstorage_protocol_version version;
    };
} __packed;

/*
 * Packet Flags:
 *
 * This flag indicates that the server should send back a completion for this
 * packet.
 */

#define REQUEST_COMPLETION_FLAG 0x1

/* Matches Windows-end */
enum storvsc_request_type {
    WRITE_TYPE = 0,
    READ_TYPE,
    UNKNOWN_TYPE,
};

/*
 * SRB status codes and masks; a subset of the codes used here.
 */

#define SRB_STATUS_AUTOSENSE_VALID  0x80
#define SRB_STATUS_INVALID_LUN  0x20
#define SRB_STATUS_SUCCESS  0x01
#define SRB_STATUS_ERROR    0x04

/*
 * This is the end of Protocol specific defines.
 */


/*
 * We setup a mempool to allocate request structures for this driver
 * on a per-lun basis. The following define specifies the number of
 * elements in the pool.
 */

#define STORVSC_MIN_BUF_NR              64
static int storvsc_ringbuffer_size = (20 * PAGE_SIZE);

module_param(storvsc_ringbuffer_size, int, S_IRUGO);
MODULE_PARM_DESC(storvsc_ringbuffer_size, "Ring buffer size (bytes)");

#define STORVSC_MAX_IO_REQUESTS             128

/*
 * In Hyper-V, each port/path/target maps to 1 scsi host adapter.  In
 * reality, the path/target is not used (ie always set to 0) so our
 * scsi host adapter essentially has 1 bus with 1 target that contains
 * up to 256 luns.
 */
#define STORVSC_MAX_LUNS_PER_TARGET         64
#define STORVSC_MAX_TARGETS             1
#define STORVSC_MAX_CHANNELS                1



struct storvsc_cmd_request {
    struct list_head entry;
    struct scsi_cmnd *cmd;

    unsigned int bounce_sgl_count;
    struct scatterlist *bounce_sgl;

    struct hv_device *device;

    /* Synchronize the request/response if needed */
    struct completion wait_event;

    unsigned char *sense_buffer;
    struct hv_multipage_buffer data_buffer;
    struct vstor_packet vstor_packet;
};


/* A storvsc device is a device object that contains a vmbus channel */
struct storvsc_device {
    struct hv_device *device;

    bool     destroy;
    bool     drain_notify;
    atomic_t num_outstanding_req;
    struct Scsi_Host *host;

    wait_queue_head_t waiting_to_drain;

    /*
     * Each unique Port/Path/Target represents 1 channel ie scsi
     * controller. In reality, the pathid, targetid is always 0
     * and the port is set by us
     */
    unsigned int port_number;
    unsigned char path_id;
    unsigned char target_id;

    /* Used for vsc/vsp channel reset process */
    struct storvsc_cmd_request init_request;
    struct storvsc_cmd_request reset_request;
};

struct stor_mem_pools {
    struct kmem_cache *request_pool;
    mempool_t *request_mempool;
};

struct hv_host_device {
    struct hv_device *dev;
    unsigned int port;
    unsigned char path;
    unsigned char target;
};

struct storvsc_scan_work {
    struct work_struct work;
    struct Scsi_Host *host;
    uint lun;
};

static void storvsc_bus_scan(struct work_struct *work)
{
    struct storvsc_scan_work *wrk;
    int id, order_id;

    wrk = container_of(work, struct storvsc_scan_work, work);
    for (id = 0; id < wrk->host->max_id; ++id) {
        if (wrk->host->reverse_ordering)
            order_id = wrk->host->max_id - id - 1;
        else
            order_id = id;

        scsi_scan_target(&wrk->host->shost_gendev, 0,
                order_id, SCAN_WILD_CARD, 1);
    }
    kfree(wrk);
}

static void storvsc_remove_lun(struct work_struct *work)
{
    struct storvsc_scan_work *wrk;
    struct scsi_device *sdev;

    wrk = container_of(work, struct storvsc_scan_work, work);
    if (!scsi_host_get(wrk->host))
        goto done;

    sdev = scsi_device_lookup(wrk->host, 0, 0, wrk->lun);

    if (sdev) {
        scsi_remove_device(sdev);
        scsi_device_put(sdev);
    }
    scsi_host_put(wrk->host);

done:
    kfree(wrk);
}

/*
 * Major/minor macros.  Minor version is in LSB, meaning that earlier flat
 * version numbers will be interpreted as "0.x" (i.e., 1 becomes 0.1).
 */

static inline u16 storvsc_get_version(u8 major, u8 minor)
{
    u16 version;

    version = ((major << 8) | minor);
    return version;
}

/*
 * We can get incoming messages from the host that are not in response to
 * messages that we have sent out. An example of this would be messages
 * received by the guest to notify dynamic addition/removal of LUNs. To
 * deal with potential race conditions where the driver may be in the
 * midst of being unloaded when we might receive an unsolicited message
 * from the host, we have implemented a mechanism to gurantee sequential
 * consistency:
 *
 * 1) Once the device is marked as being destroyed, we will fail all
 *    outgoing messages.
 * 2) We permit incoming messages when the device is being destroyed,
 *    only to properly account for messages already sent out.
 */

static inline struct storvsc_device *get_out_stor_device(
                    struct hv_device *device)
{
    struct storvsc_device *stor_device;

    stor_device = hv_get_drvdata(device);

    if (stor_device && stor_device->destroy)
        stor_device = NULL;

    return stor_device;
}


static inline void storvsc_wait_to_drain(struct storvsc_device *dev)
{
    dev->drain_notify = true;
    wait_event(dev->waiting_to_drain,
           atomic_read(&dev->num_outstanding_req) == 0);
    dev->drain_notify = false;
}

static inline struct storvsc_device *get_in_stor_device(
                    struct hv_device *device)
{
    struct storvsc_device *stor_device;

    stor_device = hv_get_drvdata(device);

    if (!stor_device)
        goto get_in_err;

    /*
     * If the device is being destroyed; allow incoming
     * traffic only to cleanup outstanding requests.
     */

    if (stor_device->destroy  &&
        (atomic_read(&stor_device->num_outstanding_req) == 0))
        stor_device = NULL;

get_in_err:
    return stor_device;

}

static void destroy_bounce_buffer(struct scatterlist *sgl,
                  unsigned int sg_count)
{
    int i;
    struct page *page_buf;

    for (i = 0; i < sg_count; i++) {
        page_buf = sg_page((&sgl[i]));
        if (page_buf != NULL)
            __free_page(page_buf);
    }

    kfree(sgl);
}

static int do_bounce_buffer(struct scatterlist *sgl, unsigned int sg_count)
{
    int i;

    /* No need to check */
    if (sg_count < 2)
        return -1;

    /* We have at least 2 sg entries */
    for (i = 0; i < sg_count; i++) {
        if (i == 0) {
            /* make sure 1st one does not have hole */
            if (sgl[i].offset + sgl[i].length != PAGE_SIZE)
                return i;
        } else if (i == sg_count - 1) {
            /* make sure last one does not have hole */
            if (sgl[i].offset != 0)
                return i;
        } else {
            /* make sure no hole in the middle */
            if (sgl[i].length != PAGE_SIZE || sgl[i].offset != 0)
                return i;
        }
    }
    return -1;
}

static struct scatterlist *create_bounce_buffer(struct scatterlist *sgl,
                        unsigned int sg_count,
                        unsigned int len,
                        int write)
{
    int i;
    int num_pages;
    struct scatterlist *bounce_sgl;
    struct page *page_buf;
    unsigned int buf_len = ((write == WRITE_TYPE) ? 0 : PAGE_SIZE);

    num_pages = ALIGN(len, PAGE_SIZE) >> PAGE_SHIFT;

    bounce_sgl = kcalloc(num_pages, sizeof(struct scatterlist), GFP_ATOMIC);
    if (!bounce_sgl)
        return NULL;

    for (i = 0; i < num_pages; i++) {
        page_buf = alloc_page(GFP_ATOMIC);
        if (!page_buf)
            goto cleanup;
        sg_set_page(&bounce_sgl[i], page_buf, buf_len, 0);
    }

    return bounce_sgl;

cleanup:
    destroy_bounce_buffer(bounce_sgl, num_pages);
    return NULL;
}

/* Disgusting wrapper functions */
static inline unsigned long sg_kmap_atomic(struct scatterlist *sgl, int idx)
{
    void *addr = kmap_atomic(sg_page(sgl + idx));
    return (unsigned long)addr;
}

static inline void sg_kunmap_atomic(unsigned long addr)
{
    kunmap_atomic((void *)addr);
}


/* Assume the original sgl has enough room */
static unsigned int copy_from_bounce_buffer(struct scatterlist *orig_sgl,
                        struct scatterlist *bounce_sgl,
                        unsigned int orig_sgl_count,
                        unsigned int bounce_sgl_count)
{
    int i;
    int j = 0;
    unsigned long src, dest;
    unsigned int srclen, destlen, copylen;
    unsigned int total_copied = 0;
    unsigned long bounce_addr = 0;
    unsigned long dest_addr = 0;
    unsigned long flags;

    local_irq_save(flags);

    for (i = 0; i < orig_sgl_count; i++) {
        dest_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
        dest = dest_addr;
        destlen = orig_sgl[i].length;

        if (bounce_addr == 0)
            bounce_addr = sg_kmap_atomic(bounce_sgl,j);

        while (destlen) {
            src = bounce_addr + bounce_sgl[j].offset;
            srclen = bounce_sgl[j].length - bounce_sgl[j].offset;

            copylen = min(srclen, destlen);
            memcpy((void *)dest, (void *)src, copylen);

            total_copied += copylen;
            bounce_sgl[j].offset += copylen;
            destlen -= copylen;
            dest += copylen;

            if (bounce_sgl[j].offset == bounce_sgl[j].length) {
                /* full */
                sg_kunmap_atomic(bounce_addr);
                j++;

                /*
                 * It is possible that the number of elements
                 * in the bounce buffer may not be equal to
                 * the number of elements in the original
                 * scatter list. Handle this correctly.
                 */

                if (j == bounce_sgl_count) {
                    /*
                     * We are done; cleanup and return.
                     */
                    sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
                    local_irq_restore(flags);
                    return total_copied;
                }

                /* if we need to use another bounce buffer */
                if (destlen || i != orig_sgl_count - 1)
                    bounce_addr = sg_kmap_atomic(bounce_sgl,j);
            } else if (destlen == 0 && i == orig_sgl_count - 1) {
                /* unmap the last bounce that is < PAGE_SIZE */
                sg_kunmap_atomic(bounce_addr);
            }
        }

        sg_kunmap_atomic(dest_addr - orig_sgl[i].offset);
    }

    local_irq_restore(flags);

    return total_copied;
}

/* Assume the bounce_sgl has enough room ie using the create_bounce_buffer() */
static unsigned int copy_to_bounce_buffer(struct scatterlist *orig_sgl,
                      struct scatterlist *bounce_sgl,
                      unsigned int orig_sgl_count)
{
    int i;
    int j = 0;
    unsigned long src, dest;
    unsigned int srclen, destlen, copylen;
    unsigned int total_copied = 0;
    unsigned long bounce_addr = 0;
    unsigned long src_addr = 0;
    unsigned long flags;

    local_irq_save(flags);

    for (i = 0; i < orig_sgl_count; i++) {
        src_addr = sg_kmap_atomic(orig_sgl,i) + orig_sgl[i].offset;
        src = src_addr;
        srclen = orig_sgl[i].length;

        if (bounce_addr == 0)
            bounce_addr = sg_kmap_atomic(bounce_sgl,j);

        while (srclen) {
            /* assume bounce offset always == 0 */
            dest = bounce_addr + bounce_sgl[j].length;
            destlen = PAGE_SIZE - bounce_sgl[j].length;

            copylen = min(srclen, destlen);
            memcpy((void *)dest, (void *)src, copylen);

            total_copied += copylen;
            bounce_sgl[j].length += copylen;
            srclen -= copylen;
            src += copylen;

            if (bounce_sgl[j].length == PAGE_SIZE) {
                /* full..move to next entry */
                sg_kunmap_atomic(bounce_addr);
                j++;

                /* if we need to use another bounce buffer */
                if (srclen || i != orig_sgl_count - 1)
                    bounce_addr = sg_kmap_atomic(bounce_sgl,j);

            } else if (srclen == 0 && i == orig_sgl_count - 1) {
                /* unmap the last bounce that is < PAGE_SIZE */
                sg_kunmap_atomic(bounce_addr);
            }
        }

        sg_kunmap_atomic(src_addr - orig_sgl[i].offset);
    }

    local_irq_restore(flags);

    return total_copied;
}

static int storvsc_channel_init(struct hv_device *device)
{
    struct storvsc_device *stor_device;
    struct storvsc_cmd_request *request;
    struct vstor_packet *vstor_packet;
    int ret, t;

    stor_device = get_out_stor_device(device);
    if (!stor_device)
        return -ENODEV;

    request = &stor_device->init_request;
    vstor_packet = &request->vstor_packet;

    /*
     * Now, initiate the vsc/vsp initialization protocol on the open
     * channel
     */
    memset(request, 0, sizeof(struct storvsc_cmd_request));
    init_completion(&request->wait_event);
    vstor_packet->operation = VSTOR_OPERATION_BEGIN_INITIALIZATION;
    vstor_packet->flags = REQUEST_COMPLETION_FLAG;

    ret = vmbus_sendpacket(device->channel, vstor_packet,
                   sizeof(struct vstor_packet),
                   (unsigned long)request,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
    if (ret != 0)
        goto cleanup;

    t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
    if (t == 0) {
        ret = -ETIMEDOUT;
        goto cleanup;
    }

    if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
        vstor_packet->status != 0)
        goto cleanup;


    /* reuse the packet for version range supported */
    memset(vstor_packet, 0, sizeof(struct vstor_packet));
    vstor_packet->operation = VSTOR_OPERATION_QUERY_PROTOCOL_VERSION;
    vstor_packet->flags = REQUEST_COMPLETION_FLAG;

    vstor_packet->version.major_minor =
        storvsc_get_version(VMSTOR_CURRENT_MAJOR, VMSTOR_CURRENT_MINOR);

    /*
     * The revision number is only used in Windows; set it to 0.
     */
    vstor_packet->version.revision = 0;

    ret = vmbus_sendpacket(device->channel, vstor_packet,
                   sizeof(struct vstor_packet),
                   (unsigned long)request,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
    if (ret != 0)
        goto cleanup;

    t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
    if (t == 0) {
        ret = -ETIMEDOUT;
        goto cleanup;
    }

    if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
        vstor_packet->status != 0)
        goto cleanup;


    memset(vstor_packet, 0, sizeof(struct vstor_packet));
    vstor_packet->operation = VSTOR_OPERATION_QUERY_PROPERTIES;
    vstor_packet->flags = REQUEST_COMPLETION_FLAG;
    vstor_packet->storage_channel_properties.port_number =
                    stor_device->port_number;

    ret = vmbus_sendpacket(device->channel, vstor_packet,
                   sizeof(struct vstor_packet),
                   (unsigned long)request,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

    if (ret != 0)
        goto cleanup;

    t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
    if (t == 0) {
        ret = -ETIMEDOUT;
        goto cleanup;
    }

    if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
        vstor_packet->status != 0)
        goto cleanup;

    stor_device->path_id = vstor_packet->storage_channel_properties.path_id;
    stor_device->target_id
        = vstor_packet->storage_channel_properties.target_id;

    memset(vstor_packet, 0, sizeof(struct vstor_packet));
    vstor_packet->operation = VSTOR_OPERATION_END_INITIALIZATION;
    vstor_packet->flags = REQUEST_COMPLETION_FLAG;

    ret = vmbus_sendpacket(device->channel, vstor_packet,
                   sizeof(struct vstor_packet),
                   (unsigned long)request,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);

    if (ret != 0)
        goto cleanup;

    t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
    if (t == 0) {
        ret = -ETIMEDOUT;
        goto cleanup;
    }

    if (vstor_packet->operation != VSTOR_OPERATION_COMPLETE_IO ||
        vstor_packet->status != 0)
        goto cleanup;


cleanup:
    return ret;
}


static void storvsc_command_completion(struct storvsc_cmd_request *cmd_request)
{
    struct scsi_cmnd *scmnd = cmd_request->cmd;
    struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
    void (*scsi_done_fn)(struct scsi_cmnd *);
    struct scsi_sense_hdr sense_hdr;
    struct vmscsi_request *vm_srb;
    struct storvsc_scan_work *wrk;
    struct stor_mem_pools *memp = scmnd->device->hostdata;

    vm_srb = &cmd_request->vstor_packet.vm_srb;
    if (cmd_request->bounce_sgl_count) {
        if (vm_srb->data_in == READ_TYPE)
            copy_from_bounce_buffer(scsi_sglist(scmnd),
                    cmd_request->bounce_sgl,
                    scsi_sg_count(scmnd),
                    cmd_request->bounce_sgl_count);
        destroy_bounce_buffer(cmd_request->bounce_sgl,
                    cmd_request->bounce_sgl_count);
    }

    /*
     * If there is an error; offline the device since all
     * error recovery strategies would have already been
     * deployed on the host side. However, if the command
     * were a pass-through command deal with it appropriately.
     */
    scmnd->result = vm_srb->scsi_status;

    if (vm_srb->srb_status == SRB_STATUS_ERROR) {
        switch (scmnd->cmnd[0]) {
        case ATA_16:
        case ATA_12:
            set_host_byte(scmnd, DID_PASSTHROUGH);
            break;
        default:
            set_host_byte(scmnd, DID_TARGET_FAILURE);
        }
    }


    /*
     * If the LUN is invalid; remove the device.
     */
    if (vm_srb->srb_status == SRB_STATUS_INVALID_LUN) {
        struct storvsc_device *stor_dev;
        struct hv_device *dev = host_dev->dev;
        struct Scsi_Host *host;

        stor_dev = get_in_stor_device(dev);
        host = stor_dev->host;

        wrk = kmalloc(sizeof(struct storvsc_scan_work),
                GFP_ATOMIC);
        if (!wrk) {
            scmnd->result = DID_TARGET_FAILURE << 16;
        } else {
            wrk->host = host;
            wrk->lun = vm_srb->lun;
            INIT_WORK(&wrk->work, storvsc_remove_lun);
            schedule_work(&wrk->work);
        }
    }

    if (scmnd->result) {
        if (scsi_normalize_sense(scmnd->sense_buffer,
                SCSI_SENSE_BUFFERSIZE, &sense_hdr))
            scsi_print_sense_hdr("storvsc", &sense_hdr);
    }

    scsi_set_resid(scmnd,
        cmd_request->data_buffer.len -
        vm_srb->data_transfer_length);

    scsi_done_fn = scmnd->scsi_done;

    scmnd->host_scribble = NULL;
    scmnd->scsi_done = NULL;

    scsi_done_fn(scmnd);

    mempool_free(cmd_request, memp->request_mempool);
}

static void storvsc_on_io_completion(struct hv_device *device,
                  struct vstor_packet *vstor_packet,
                  struct storvsc_cmd_request *request)
{
    struct storvsc_device *stor_device;
    struct vstor_packet *stor_pkt;

    stor_device = hv_get_drvdata(device);
    stor_pkt = &request->vstor_packet;

    /*
     * The current SCSI handling on the host side does
     * not correctly handle:
     * INQUIRY command with page code parameter set to 0x80
     * MODE_SENSE command with cmd[2] == 0x1c
     *
     * Setup srb and scsi status so this won't be fatal.
     * We do this so we can distinguish truly fatal failues
     * (srb status == 0x4) and off-line the device in that case.
     */

    if ((stor_pkt->vm_srb.cdb[0] == INQUIRY) ||
       (stor_pkt->vm_srb.cdb[0] == MODE_SENSE)) {
        vstor_packet->vm_srb.scsi_status = 0;
        vstor_packet->vm_srb.srb_status = SRB_STATUS_SUCCESS;
    }


    /* Copy over the status...etc */
    stor_pkt->vm_srb.scsi_status = vstor_packet->vm_srb.scsi_status;
    stor_pkt->vm_srb.srb_status = vstor_packet->vm_srb.srb_status;
    stor_pkt->vm_srb.sense_info_length =
    vstor_packet->vm_srb.sense_info_length;

    if (vstor_packet->vm_srb.scsi_status != 0 ||
        vstor_packet->vm_srb.srb_status != SRB_STATUS_SUCCESS){
        dev_warn(&device->device,
             "cmd 0x%x scsi status 0x%x srb status 0x%x\n",
             stor_pkt->vm_srb.cdb[0],
             vstor_packet->vm_srb.scsi_status,
             vstor_packet->vm_srb.srb_status);
    }

    if ((vstor_packet->vm_srb.scsi_status & 0xFF) == 0x02) {
        /* CHECK_CONDITION */
        if (vstor_packet->vm_srb.srb_status &
            SRB_STATUS_AUTOSENSE_VALID) {
            /* autosense data available */
            dev_warn(&device->device,
                 "stor pkt %p autosense data valid - len %d\n",
                 request,
                 vstor_packet->vm_srb.sense_info_length);

            memcpy(request->sense_buffer,
                   vstor_packet->vm_srb.sense_data,
                   vstor_packet->vm_srb.sense_info_length);

        }
    }

    stor_pkt->vm_srb.data_transfer_length =
    vstor_packet->vm_srb.data_transfer_length;

    storvsc_command_completion(request);

    if (atomic_dec_and_test(&stor_device->num_outstanding_req) &&
        stor_device->drain_notify)
        wake_up(&stor_device->waiting_to_drain);


}

static void storvsc_on_receive(struct hv_device *device,
                 struct vstor_packet *vstor_packet,
                 struct storvsc_cmd_request *request)
{
    struct storvsc_scan_work *work;
    struct storvsc_device *stor_device;

    switch (vstor_packet->operation) {
    case VSTOR_OPERATION_COMPLETE_IO:
        storvsc_on_io_completion(device, vstor_packet, request);
        break;

    case VSTOR_OPERATION_REMOVE_DEVICE:
    case VSTOR_OPERATION_ENUMERATE_BUS:
        stor_device = get_in_stor_device(device);
        work = kmalloc(sizeof(struct storvsc_scan_work), GFP_ATOMIC);
        if (!work)
            return;

        INIT_WORK(&work->work, storvsc_bus_scan);
        work->host = stor_device->host;
        schedule_work(&work->work);
        break;

    default:
        break;
    }
}

static void storvsc_on_channel_callback(void *context)
{
    struct hv_device *device = (struct hv_device *)context;
    struct storvsc_device *stor_device;
    u32 bytes_recvd;
    u64 request_id;
    unsigned char packet[ALIGN(sizeof(struct vstor_packet), 8)];
    struct storvsc_cmd_request *request;
    int ret;


    stor_device = get_in_stor_device(device);
    if (!stor_device)
        return;

    do {
        ret = vmbus_recvpacket(device->channel, packet,
                       ALIGN(sizeof(struct vstor_packet), 8),
                       &bytes_recvd, &request_id);
        if (ret == 0 && bytes_recvd > 0) {

            request = (struct storvsc_cmd_request *)
                    (unsigned long)request_id;

            if ((request == &stor_device->init_request) ||
                (request == &stor_device->reset_request)) {

                memcpy(&request->vstor_packet, packet,
                       sizeof(struct vstor_packet));
                complete(&request->wait_event);
            } else {
                storvsc_on_receive(device,
                        (struct vstor_packet *)packet,
                        request);
            }
        } else {
            break;
        }
    } while (1);

    return;
}

static int storvsc_connect_to_vsp(struct hv_device *device, u32 ring_size)
{
    struct vmstorage_channel_properties props;
    int ret;

    memset(&props, 0, sizeof(struct vmstorage_channel_properties));

    ret = vmbus_open(device->channel,
             ring_size,
             ring_size,
             (void *)&props,
             sizeof(struct vmstorage_channel_properties),
             storvsc_on_channel_callback, device);

    if (ret != 0)
        return ret;

    ret = storvsc_channel_init(device);

    return ret;
}

static int storvsc_dev_remove(struct hv_device *device)
{
    struct storvsc_device *stor_device;
    unsigned long flags;

    stor_device = hv_get_drvdata(device);

    spin_lock_irqsave(&device->channel->inbound_lock, flags);
    stor_device->destroy = true;
    spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

    /*
     * At this point, all outbound traffic should be disable. We
     * only allow inbound traffic (responses) to proceed so that
     * outstanding requests can be completed.
     */

    storvsc_wait_to_drain(stor_device);

    /*
     * Since we have already drained, we don't need to busy wait
     * as was done in final_release_stor_device()
     * Note that we cannot set the ext pointer to NULL until
     * we have drained - to drain the outgoing packets, we need to
     * allow incoming packets.
     */
    spin_lock_irqsave(&device->channel->inbound_lock, flags);
    hv_set_drvdata(device, NULL);
    spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

    /* Close the channel */
    vmbus_close(device->channel);

    kfree(stor_device);
    return 0;
}

static int storvsc_do_io(struct hv_device *device,
                  struct storvsc_cmd_request *request)
{
    struct storvsc_device *stor_device;
    struct vstor_packet *vstor_packet;
    int ret = 0;

    vstor_packet = &request->vstor_packet;
    stor_device = get_out_stor_device(device);

    if (!stor_device)
        return -ENODEV;


    request->device  = device;


    vstor_packet->flags |= REQUEST_COMPLETION_FLAG;

    vstor_packet->vm_srb.length = sizeof(struct vmscsi_request);


    vstor_packet->vm_srb.sense_info_length = STORVSC_SENSE_BUFFER_SIZE;


    vstor_packet->vm_srb.data_transfer_length =
    request->data_buffer.len;

    vstor_packet->operation = VSTOR_OPERATION_EXECUTE_SRB;

    if (request->data_buffer.len) {
        ret = vmbus_sendpacket_multipagebuffer(device->channel,
                &request->data_buffer,
                vstor_packet,
                sizeof(struct vstor_packet),
                (unsigned long)request);
    } else {
        ret = vmbus_sendpacket(device->channel, vstor_packet,
                   sizeof(struct vstor_packet),
                   (unsigned long)request,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
    }

    if (ret != 0)
        return ret;

    atomic_inc(&stor_device->num_outstanding_req);

    return ret;
}

static int storvsc_device_alloc(struct scsi_device *sdevice)
{
    struct stor_mem_pools *memp;
    int number = STORVSC_MIN_BUF_NR;

    memp = kzalloc(sizeof(struct stor_mem_pools), GFP_KERNEL);
    if (!memp)
        return -ENOMEM;

    memp->request_pool =
        kmem_cache_create(dev_name(&sdevice->sdev_dev),
                sizeof(struct storvsc_cmd_request), 0,
                SLAB_HWCACHE_ALIGN, NULL);

    if (!memp->request_pool)
        goto err0;

    memp->request_mempool = mempool_create(number, mempool_alloc_slab,
                        mempool_free_slab,
                        memp->request_pool);

    if (!memp->request_mempool)
        goto err1;

    sdevice->hostdata = memp;

    return 0;

err1:
    kmem_cache_destroy(memp->request_pool);

err0:
    kfree(memp);
    return -ENOMEM;
}

static void storvsc_device_destroy(struct scsi_device *sdevice)
{
    struct stor_mem_pools *memp = sdevice->hostdata;

    mempool_destroy(memp->request_mempool);
    kmem_cache_destroy(memp->request_pool);
    kfree(memp);
    sdevice->hostdata = NULL;
}

static int storvsc_device_configure(struct scsi_device *sdevice)
{
    scsi_adjust_queue_depth(sdevice, MSG_SIMPLE_TAG,
                STORVSC_MAX_IO_REQUESTS);

    blk_queue_max_segment_size(sdevice->request_queue, PAGE_SIZE);

    blk_queue_bounce_limit(sdevice->request_queue, BLK_BOUNCE_ANY);

    return 0;
}

static int storvsc_get_chs(struct scsi_device *sdev, struct block_device * bdev,
               sector_t capacity, int *info)
{
    sector_t nsect = capacity;
    sector_t cylinders = nsect;
    int heads, sectors_pt;

    /*
     * We are making up these values; let us keep it simple.
     */
    heads = 0xff;
    sectors_pt = 0x3f;      /* Sectors per track */
    sector_div(cylinders, heads * sectors_pt);
    if ((sector_t)(cylinders + 1) * heads * sectors_pt < nsect)
        cylinders = 0xffff;

    info[0] = heads;
    info[1] = sectors_pt;
    info[2] = (int)cylinders;

    return 0;
}

static int storvsc_host_reset_handler(struct scsi_cmnd *scmnd)
{
    struct hv_host_device *host_dev = shost_priv(scmnd->device->host);
    struct hv_device *device = host_dev->dev;

    struct storvsc_device *stor_device;
    struct storvsc_cmd_request *request;
    struct vstor_packet *vstor_packet;
    int ret, t;


    stor_device = get_out_stor_device(device);
    if (!stor_device)
        return FAILED;

    request = &stor_device->reset_request;
    vstor_packet = &request->vstor_packet;

    init_completion(&request->wait_event);

    vstor_packet->operation = VSTOR_OPERATION_RESET_BUS;
    vstor_packet->flags = REQUEST_COMPLETION_FLAG;
    vstor_packet->vm_srb.path_id = stor_device->path_id;

    ret = vmbus_sendpacket(device->channel, vstor_packet,
                   sizeof(struct vstor_packet),
                   (unsigned long)&stor_device->reset_request,
                   VM_PKT_DATA_INBAND,
                   VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
    if (ret != 0)
        return FAILED;

    t = wait_for_completion_timeout(&request->wait_event, 5*HZ);
    if (t == 0)
        return TIMEOUT_ERROR;


    /*
     * At this point, all outstanding requests in the adapter
     * should have been flushed out and return to us
     * There is a potential race here where the host may be in
     * the process of responding when we return from here.
     * Just wait for all in-transit packets to be accounted for
     * before we return from here.
     */
    storvsc_wait_to_drain(stor_device);

    return SUCCESS;
}

static bool storvsc_scsi_cmd_ok(struct scsi_cmnd *scmnd)
{
    bool allowed = true;
    u8 scsi_op = scmnd->cmnd[0];

    switch (scsi_op) {
    /*
     * smartd sends this command and the host does not handle
     * this. So, don't send it.
     */
    case SET_WINDOW:
        scmnd->result = ILLEGAL_REQUEST << 16;
        allowed = false;
        break;
    default:
        break;
    }
    return allowed;
}

static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
{
    int ret;
    struct hv_host_device *host_dev = shost_priv(host);
    struct hv_device *dev = host_dev->dev;
    struct storvsc_cmd_request *cmd_request;
    unsigned int request_size = 0;
    int i;
    struct scatterlist *sgl;
    unsigned int sg_count = 0;
    struct vmscsi_request *vm_srb;
    struct stor_mem_pools *memp = scmnd->device->hostdata;

    if (!storvsc_scsi_cmd_ok(scmnd)) {
        scmnd->scsi_done(scmnd);
        return 0;
    }

    request_size = sizeof(struct storvsc_cmd_request);

    cmd_request = mempool_alloc(memp->request_mempool,
                       GFP_ATOMIC);

    /*
     * We might be invoked in an interrupt context; hence
     * mempool_alloc() can fail.
     */
    if (!cmd_request)
        return SCSI_MLQUEUE_DEVICE_BUSY;

    memset(cmd_request, 0, sizeof(struct storvsc_cmd_request));

    /* Setup the cmd request */
    cmd_request->cmd = scmnd;

    scmnd->host_scribble = (unsigned char *)cmd_request;

    vm_srb = &cmd_request->vstor_packet.vm_srb;


    /* Build the SRB */
    switch (scmnd->sc_data_direction) {
    case DMA_TO_DEVICE:
        vm_srb->data_in = WRITE_TYPE;
        break;
    case DMA_FROM_DEVICE:
        vm_srb->data_in = READ_TYPE;
        break;
    default:
        vm_srb->data_in = UNKNOWN_TYPE;
        break;
    }


    vm_srb->port_number = host_dev->port;
    vm_srb->path_id = scmnd->device->channel;
    vm_srb->target_id = scmnd->device->id;
    vm_srb->lun = scmnd->device->lun;

    vm_srb->cdb_length = scmnd->cmd_len;

    memcpy(vm_srb->cdb, scmnd->cmnd, vm_srb->cdb_length);

    cmd_request->sense_buffer = scmnd->sense_buffer;


    cmd_request->data_buffer.len = scsi_bufflen(scmnd);
    if (scsi_sg_count(scmnd)) {
        sgl = (struct scatterlist *)scsi_sglist(scmnd);
        sg_count = scsi_sg_count(scmnd);

        /* check if we need to bounce the sgl */
        if (do_bounce_buffer(sgl, scsi_sg_count(scmnd)) != -1) {
            cmd_request->bounce_sgl =
                create_bounce_buffer(sgl, scsi_sg_count(scmnd),
                             scsi_bufflen(scmnd),
                             vm_srb->data_in);
            if (!cmd_request->bounce_sgl) {
                ret = SCSI_MLQUEUE_HOST_BUSY;
                goto queue_error;
            }

            cmd_request->bounce_sgl_count =
                ALIGN(scsi_bufflen(scmnd), PAGE_SIZE) >>
                    PAGE_SHIFT;

            if (vm_srb->data_in == WRITE_TYPE)
                copy_to_bounce_buffer(sgl,
                    cmd_request->bounce_sgl,
                    scsi_sg_count(scmnd));

            sgl = cmd_request->bounce_sgl;
            sg_count = cmd_request->bounce_sgl_count;
        }

        cmd_request->data_buffer.offset = sgl[0].offset;

        for (i = 0; i < sg_count; i++)
            cmd_request->data_buffer.pfn_array[i] =
                page_to_pfn(sg_page((&sgl[i])));

    } else if (scsi_sglist(scmnd)) {
        cmd_request->data_buffer.offset =
            virt_to_phys(scsi_sglist(scmnd)) & (PAGE_SIZE-1);
        cmd_request->data_buffer.pfn_array[0] =
            virt_to_phys(scsi_sglist(scmnd)) >> PAGE_SHIFT;
    }

    /* Invokes the vsc to start an IO */
    ret = storvsc_do_io(dev, cmd_request);

    if (ret == -EAGAIN) {
        /* no more space */

        if (cmd_request->bounce_sgl_count) {
            destroy_bounce_buffer(cmd_request->bounce_sgl,
                    cmd_request->bounce_sgl_count);

            ret = SCSI_MLQUEUE_DEVICE_BUSY;
            goto queue_error;
        }
    }

    return 0;

queue_error:
    mempool_free(cmd_request, memp->request_mempool);
    scmnd->host_scribble = NULL;
    return ret;
}

static struct scsi_host_template scsi_driver = {
    .module =       THIS_MODULE,
    .name =         "storvsc_host_t",
    .bios_param =       storvsc_get_chs,
    .queuecommand =     storvsc_queuecommand,
    .eh_host_reset_handler =    storvsc_host_reset_handler,
    .slave_alloc =      storvsc_device_alloc,
    .slave_destroy =    storvsc_device_destroy,
    .slave_configure =  storvsc_device_configure,
    .cmd_per_lun =      1,
    /* 64 max_queue * 1 target */
    .can_queue =        STORVSC_MAX_IO_REQUESTS*STORVSC_MAX_TARGETS,
    .this_id =      -1,
    /* no use setting to 0 since ll_blk_rw reset it to 1 */
    /* currently 32 */
    .sg_tablesize =     MAX_MULTIPAGE_BUFFER_COUNT,
    .use_clustering =   DISABLE_CLUSTERING,
    /* Make sure we dont get a sg segment crosses a page boundary */
    .dma_boundary =     PAGE_SIZE-1,
};

enum {
    SCSI_GUID,
    IDE_GUID,
};

static const struct hv_vmbus_device_id id_table[] = {
    /* SCSI guid */
    { VMBUS_DEVICE(0xd9, 0x63, 0x61, 0xba, 0xa1, 0x04, 0x29, 0x4d,
               0xb6, 0x05, 0x72, 0xe2, 0xff, 0xb1, 0xdc, 0x7f)
      .driver_data = SCSI_GUID },
    /* IDE guid */
    { VMBUS_DEVICE(0x32, 0x26, 0x41, 0x32, 0xcb, 0x86, 0xa2, 0x44,
               0x9b, 0x5c, 0x50, 0xd1, 0x41, 0x73, 0x54, 0xf5)
      .driver_data = IDE_GUID },
    { },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

static int storvsc_probe(struct hv_device *device,
            const struct hv_vmbus_device_id *dev_id)
{
    int ret;
    struct Scsi_Host *host;
    struct hv_host_device *host_dev;
    bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
    int target = 0;
    struct storvsc_device *stor_device;

    host = scsi_host_alloc(&scsi_driver,
                   sizeof(struct hv_host_device));
    if (!host)
        return -ENOMEM;

    host_dev = shost_priv(host);
    memset(host_dev, 0, sizeof(struct hv_host_device));

    host_dev->port = host->host_no;
    host_dev->dev = device;


    stor_device = kzalloc(sizeof(struct storvsc_device), GFP_KERNEL);
    if (!stor_device) {
        ret = -ENOMEM;
        goto err_out0;
    }

    stor_device->destroy = false;
    init_waitqueue_head(&stor_device->waiting_to_drain);
    stor_device->device = device;
    stor_device->host = host;
    hv_set_drvdata(device, stor_device);

    stor_device->port_number = host->host_no;
    ret = storvsc_connect_to_vsp(device, storvsc_ringbuffer_size);
    if (ret)
        goto err_out1;

    host_dev->path = stor_device->path_id;
    host_dev->target = stor_device->target_id;

    /* max # of devices per target */
    host->max_lun = STORVSC_MAX_LUNS_PER_TARGET;
    /* max # of targets per channel */
    host->max_id = STORVSC_MAX_TARGETS;
    /* max # of channels */
    host->max_channel = STORVSC_MAX_CHANNELS - 1;
    /* max cmd length */
    host->max_cmd_len = STORVSC_MAX_CMD_LEN;

    /* Register the HBA and start the scsi bus scan */
    ret = scsi_add_host(host, &device->device);
    if (ret != 0)
        goto err_out2;

    if (!dev_is_ide) {
        scsi_scan_host(host);
    } else {
        target = (device->dev_instance.b[5] << 8 |
             device->dev_instance.b[4]);
        ret = scsi_add_device(host, 0, target, 0);
        if (ret) {
            scsi_remove_host(host);
            goto err_out2;
        }
    }
    return 0;

err_out2:
    /*
     * Once we have connected with the host, we would need to
     * to invoke storvsc_dev_remove() to rollback this state and
     * this call also frees up the stor_device; hence the jump around
     * err_out1 label.
     */
    storvsc_dev_remove(device);
    goto err_out0;

err_out1:
    kfree(stor_device);

err_out0:
    scsi_host_put(host);
    return ret;
}

static int storvsc_remove(struct hv_device *dev)
{
    struct storvsc_device *stor_device = hv_get_drvdata(dev);
    struct Scsi_Host *host = stor_device->host;

    scsi_remove_host(host);
    storvsc_dev_remove(dev);
    scsi_host_put(host);

    return 0;
}

static struct hv_driver storvsc_drv = {
    .name = KBUILD_MODNAME,
    .id_table = id_table,
    .probe = storvsc_probe,
    .remove = storvsc_remove,
};

static int __init storvsc_drv_init(void)
{
    u32 max_outstanding_req_per_channel;

    /*
     * Divide the ring buffer data size (which is 1 page less
     * than the ring buffer size since that page is reserved for
     * the ring buffer indices) by the max request size (which is
     * vmbus_channel_packet_multipage_buffer + struct vstor_packet + u64)
     */
    max_outstanding_req_per_channel =
        ((storvsc_ringbuffer_size - PAGE_SIZE) /
        ALIGN(MAX_MULTIPAGE_BUFFER_PACKET +
        sizeof(struct vstor_packet) + sizeof(u64),
        sizeof(u64)));

    if (max_outstanding_req_per_channel <
        STORVSC_MAX_IO_REQUESTS)
        return -EINVAL;

    return vmbus_driver_register(&storvsc_drv);
}

static void __exit storvsc_drv_exit(void)
{
    vmbus_driver_unregister(&storvsc_drv);
}

MODULE_LICENSE("GPL");
MODULE_VERSION(HV_DRV_VERSION);
MODULE_DESCRIPTION("Microsoft Hyper-V virtual storage driver");
module_init(storvsc_drv_init);
module_exit(storvsc_drv_exit);