Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[deliverable/linux.git] / drivers / hv / hv_balloon.c

/*
 * Copyright (c) 2012, Microsoft Corporation.
 *
 * Author:
 *   K. Y. Srinivasan <kys@microsoft.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/mman.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/completion.h>
#include <linux/memory_hotplug.h>
#include <linux/memory.h>
#include <linux/notifier.h>
#include <linux/percpu_counter.h>

#include <linux/hyperv.h>

/*
 * We begin with definitions supporting the Dynamic Memory protocol
 * with the host.
 *
 * Begin protocol definitions.
 */



/*
 * Protocol versions. The low word is the minor version, the high word the major
 * version.
 *
 * History:
 * Initial version 1.0
 * Changed to 0.1 on 2009/03/25
 * Changes to 0.2 on 2009/05/14
 * Changes to 0.3 on 2009/12/03
 * Changed to 1.0 on 2011/04/05
 */

#define DYNMEM_MAKE_VERSION(Major, Minor) ((__u32)(((Major) << 16) | (Minor)))
#define DYNMEM_MAJOR_VERSION(Version) ((__u32)(Version) >> 16)
#define DYNMEM_MINOR_VERSION(Version) ((__u32)(Version) & 0xff)

enum {
        DYNMEM_PROTOCOL_VERSION_1 = DYNMEM_MAKE_VERSION(0, 3),
        DYNMEM_PROTOCOL_VERSION_2 = DYNMEM_MAKE_VERSION(1, 0),

        DYNMEM_PROTOCOL_VERSION_WIN7 = DYNMEM_PROTOCOL_VERSION_1,
        DYNMEM_PROTOCOL_VERSION_WIN8 = DYNMEM_PROTOCOL_VERSION_2,

        DYNMEM_PROTOCOL_VERSION_CURRENT = DYNMEM_PROTOCOL_VERSION_WIN8
};



/*
 * Message Types
 */

enum dm_message_type {
        /*
         * Version 0.3
         */
        DM_ERROR                        = 0,
        DM_VERSION_REQUEST              = 1,
        DM_VERSION_RESPONSE             = 2,
        DM_CAPABILITIES_REPORT          = 3,
        DM_CAPABILITIES_RESPONSE        = 4,
        DM_STATUS_REPORT                = 5,
        DM_BALLOON_REQUEST              = 6,
        DM_BALLOON_RESPONSE             = 7,
        DM_UNBALLOON_REQUEST            = 8,
        DM_UNBALLOON_RESPONSE           = 9,
        DM_MEM_HOT_ADD_REQUEST          = 10,
        DM_MEM_HOT_ADD_RESPONSE         = 11,
        DM_VERSION_03_MAX               = 11,
        /*
         * Version 1.0.
         */
        DM_INFO_MESSAGE                 = 12,
        DM_VERSION_1_MAX                = 12
};


/*
 * Structures defining the dynamic memory management
 * protocol.
 */

union dm_version {
        struct {
                __u16 minor_version;
                __u16 major_version;
        };
        __u32 version;
} __packed;


union dm_caps {
        struct {
                __u64 balloon:1;
                __u64 hot_add:1;
                __u64 reservedz:62;
        } cap_bits;
        __u64 caps;
} __packed;

union dm_mem_page_range {
        struct  {
                /*
                 * The PFN number of the first page in the range.
                 * 40 bits is the architectural limit of a PFN
                 * number for AMD64.
                 */
                __u64 start_page:40;
                /*
                 * The number of pages in the range.
                 */
                __u64 page_cnt:24;
        } finfo;
        __u64  page_range;
} __packed;



/*
 * The header for all dynamic memory messages:
 *
 * type: Type of the message.
 * size: Size of the message in bytes; including the header.
 * trans_id: The guest is responsible for manufacturing this ID.
 */

struct dm_header {
        __u16 type;
        __u16 size;
        __u32 trans_id;
} __packed;

/*
 * A generic message format for dynamic memory.
 * Specific message formats are defined later in the file.
 */

struct dm_message {
        struct dm_header hdr;
        __u8 data[]; /* enclosed message */
} __packed;


/*
 * Specific message types supporting the dynamic memory protocol.
 */

/*
 * Version negotiation message. Sent from the guest to the host.
 * The guest is free to try different versions until the host
 * accepts the version.
 *
 * dm_version: The protocol version requested.
 * is_last_attempt: If TRUE, this is the last version guest will request.
 * reservedz: Reserved field, set to zero.
 */

struct dm_version_request {
        struct dm_header hdr;
        union dm_version version;
        __u32 is_last_attempt:1;
        __u32 reservedz:31;
} __packed;

/*
 * Version response message; Host to Guest and indicates
 * if the host has accepted the version sent by the guest.
 *
 * is_accepted: If TRUE, host has accepted the version and the guest
 * should proceed to the next stage of the protocol. FALSE indicates that
 * guest should re-try with a different version.
 *
 * reservedz: Reserved field, set to zero.
 */

struct dm_version_response {
        struct dm_header hdr;
        __u64 is_accepted:1;
        __u64 reservedz:63;
} __packed;

/*
 * Message reporting capabilities. This is sent from the guest to the
 * host.
 */

struct dm_capabilities {
        struct dm_header hdr;
        union dm_caps caps;
        __u64 min_page_cnt;
        __u64 max_page_number;
} __packed;

/*
 * Response to the capabilities message. This is sent from the host to the
 * guest. This message notifies if the host has accepted the guest's
 * capabilities. If the host has not accepted, the guest must shutdown
 * the service.
 *
 * is_accepted: Indicates if the host has accepted guest's capabilities.
 * reservedz: Must be 0.
 */

struct dm_capabilities_resp_msg {
        struct dm_header hdr;
        __u64 is_accepted:1;
        __u64 reservedz:63;
} __packed;

/*
 * This message is used to report memory pressure from the guest.
 * This message is not part of any transaction and there is no
 * response to this message.
 *
 * num_avail: Available memory in pages.
 * num_committed: Committed memory in pages.
 * page_file_size: The accumulated size of all page files
 *                 in the system in pages.
 * zero_free: The nunber of zero and free pages.
 * page_file_writes: The writes to the page file in pages.
 * io_diff: An indicator of file cache efficiency or page file activity,
 *          calculated as File Cache Page Fault Count - Page Read Count.
 *          This value is in pages.
 *
 * Some of these metrics are Windows specific and fortunately
 * the algorithm on the host side that computes the guest memory
 * pressure only uses num_committed value.
 */

struct dm_status {
        struct dm_header hdr;
        __u64 num_avail;
        __u64 num_committed;
        __u64 page_file_size;
        __u64 zero_free;
        __u32 page_file_writes;
        __u32 io_diff;
} __packed;


/*
 * Message to ask the guest to allocate memory - balloon up message.
 * This message is sent from the host to the guest. The guest may not be
 * able to allocate as much memory as requested.
 *
 * num_pages: number of pages to allocate.
 */

struct dm_balloon {
        struct dm_header hdr;
        __u32 num_pages;
        __u32 reservedz;
} __packed;


/*
 * Balloon response message; this message is sent from the guest
 * to the host in response to the balloon message.
 *
 * reservedz: Reserved; must be set to zero.
 * more_pages: If FALSE, this is the last message of the transaction.
 * if TRUE there will atleast one more message from the guest.
 *
 * range_count: The number of ranges in the range array.
 *
 * range_array: An array of page ranges returned to the host.
 *
 */

struct dm_balloon_response {
        struct dm_header hdr;
        __u32 reservedz;
        __u32 more_pages:1;
        __u32 range_count:31;
        union dm_mem_page_range range_array[];
} __packed;

/*
 * Un-balloon message; this message is sent from the host
 * to the guest to give guest more memory.
 *
 * more_pages: If FALSE, this is the last message of the transaction.
 * if TRUE there will atleast one more message from the guest.
 *
 * reservedz: Reserved; must be set to zero.
 *
 * range_count: The number of ranges in the range array.
 *
 * range_array: An array of page ranges returned to the host.
 *
 */

struct dm_unballoon_request {
        struct dm_header hdr;
        __u32 more_pages:1;
        __u32 reservedz:31;
        __u32 range_count;
        union dm_mem_page_range range_array[];
} __packed;

/*
 * Un-balloon response message; this message is sent from the guest
 * to the host in response to an unballoon request.
 *
 */

struct dm_unballoon_response {
        struct dm_header hdr;
} __packed;


/*
 * Hot add request message. Message sent from the host to the guest.
 *
 * mem_range: Memory range to hot add.
 *
 * On Linux we currently don't support this since we cannot hot add
 * arbitrary granularity of memory.
 */

struct dm_hot_add {
        struct dm_header hdr;
        union dm_mem_page_range range;
} __packed;

/*
 * Hot add response message.
 * This message is sent by the guest to report the status of a hot add request.
 * If page_count is less than the requested page count, then the host should
 * assume all further hot add requests will fail, since this indicates that
 * the guest has hit an upper physical memory barrier.
 *
 * Hot adds may also fail due to low resources; in this case, the guest must
 * not complete this message until the hot add can succeed, and the host must
 * not send a new hot add request until the response is sent.
 * If VSC fails to hot add memory DYNMEM_NUMBER_OF_UNSUCCESSFUL_HOTADD_ATTEMPTS
 * times it fails the request.
 *
 *
 * page_count: number of pages that were successfully hot added.
 *
 * result: result of the operation 1: success, 0: failure.
 *
 */

struct dm_hot_add_response {
        struct dm_header hdr;
        __u32 page_count;
        __u32 result;
} __packed;

/*
 * Types of information sent from host to the guest.
 */

enum dm_info_type {
        INFO_TYPE_MAX_PAGE_CNT = 0,
        MAX_INFO_TYPE
};


/*
 * Header for the information message.
 */

struct dm_info_header {
        enum dm_info_type type;
        __u32 data_size;
} __packed;

/*
 * This message is sent from the host to the guest to pass
 * some relevant information (win8 addition).
 *
 * reserved: no used.
 * info_size: size of the information blob.
 * info: information blob.
 */

struct dm_info_msg {
        struct dm_header hdr;
        __u32 reserved;
        __u32 info_size;
        __u8  info[];
};

/*
 * End protocol definitions.
 */

static bool hot_add;
static bool do_hot_add;
/*
 * Delay reporting memory pressure by
 * the specified number of seconds.
 */
static uint pressure_report_delay = 30;

module_param(hot_add, bool, (S_IRUGO | S_IWUSR));
MODULE_PARM_DESC(hot_add, "If set attempt memory hot_add");

module_param(pressure_report_delay, uint, (S_IRUGO | S_IWUSR));
MODULE_PARM_DESC(pressure_report_delay, "Delay in secs in reporting pressure");
static atomic_t trans_id = ATOMIC_INIT(0);

static int dm_ring_size = (5 * PAGE_SIZE);

/*
 * Driver specific state.
 */

enum hv_dm_state {
        DM_INITIALIZING = 0,
        DM_INITIALIZED,
        DM_BALLOON_UP,
        DM_BALLOON_DOWN,
        DM_HOT_ADD,
        DM_INIT_ERROR
};


static __u8 recv_buffer[PAGE_SIZE];
static __u8 *send_buffer;
#define PAGES_IN_2M     512

struct hv_dynmem_device {
        struct hv_device *dev;
        enum hv_dm_state state;
        struct completion host_event;
        struct completion config_event;

        /*
         * Number of pages we have currently ballooned out.
         */
        unsigned int num_pages_ballooned;

        /*
         * This thread handles both balloon/hot-add
         * requests from the host as well as notifying
         * the host with regards to memory pressure in
         * the guest.
         */
        struct task_struct *thread;

        /*
         * We start with the highest version we can support
         * and downgrade based on the host; we save here the
         * next version to try.
         */
        __u32 next_version;
};

static struct hv_dynmem_device dm_device;

static void hot_add_req(struct hv_dynmem_device *dm, struct dm_hot_add *msg)
{

        struct dm_hot_add_response resp;

        if (do_hot_add) {

                pr_info("Memory hot add not supported\n");

                /*
                 * Currently we do not support hot add.
                 * Just fail the request.
                 */
        }

        memset(&resp, 0, sizeof(struct dm_hot_add_response));
        resp.hdr.type = DM_MEM_HOT_ADD_RESPONSE;
        resp.hdr.size = sizeof(struct dm_hot_add_response);
        resp.hdr.trans_id = atomic_inc_return(&trans_id);

        resp.page_count = 0;
        resp.result = 0;

        dm->state = DM_INITIALIZED;
        vmbus_sendpacket(dm->dev->channel, &resp,
                        sizeof(struct dm_hot_add_response),
                        (unsigned long)NULL,
                        VM_PKT_DATA_INBAND, 0);

}

static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
{
        struct dm_info_header *info_hdr;

        info_hdr = (struct dm_info_header *)msg->info;

        switch (info_hdr->type) {
        case INFO_TYPE_MAX_PAGE_CNT:
                pr_info("Received INFO_TYPE_MAX_PAGE_CNT\n");
                pr_info("Data Size is %d\n", info_hdr->data_size);
                break;
        default:
                pr_info("Received Unknown type: %d\n", info_hdr->type);
        }
}

unsigned long compute_balloon_floor(void)
{
        unsigned long min_pages;
#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
        /* Simple continuous piecewiese linear function:
         *  max MiB -> min MiB  gradient
         *       0         0
         *      16        16
         *      32        24
         *     128        72    (1/2)
         *     512       168    (1/4)
         *    2048       360    (1/8)
         *    8192       552    (1/32)
         *   32768      1320
         *  131072      4392
         */
        if (totalram_pages < MB2PAGES(128))
                min_pages = MB2PAGES(8) + (totalram_pages >> 1);
        else if (totalram_pages < MB2PAGES(512))
                min_pages = MB2PAGES(40) + (totalram_pages >> 2);
        else if (totalram_pages < MB2PAGES(2048))
                min_pages = MB2PAGES(104) + (totalram_pages >> 3);
        else
                min_pages = MB2PAGES(296) + (totalram_pages >> 5);
#undef MB2PAGES
        return min_pages;
}

/*
 * Post our status as it relates memory pressure to the
 * host. Host expects the guests to post this status
 * periodically at 1 second intervals.
 *
 * The metrics specified in this protocol are very Windows
 * specific and so we cook up numbers here to convey our memory
 * pressure.
 */

static void post_status(struct hv_dynmem_device *dm)
{
        struct dm_status status;
        struct sysinfo val;

        if (pressure_report_delay > 0) {
                --pressure_report_delay;
                return;
        }
        si_meminfo(&val);
        memset(&status, 0, sizeof(struct dm_status));
        status.hdr.type = DM_STATUS_REPORT;
        status.hdr.size = sizeof(struct dm_status);
        status.hdr.trans_id = atomic_inc_return(&trans_id);

        /*
         * The host expects the guest to report free memory.
         * Further, the host expects the pressure information to
         * include the ballooned out pages.
         * For a given amount of memory that we are managing, we
         * need to compute a floor below which we should not balloon.
         * Compute this and add it to the pressure report.
         */
        status.num_avail = val.freeram;
        status.num_committed = vm_memory_committed() +
                                dm->num_pages_ballooned +
                                compute_balloon_floor();

        vmbus_sendpacket(dm->dev->channel, &status,
                                sizeof(struct dm_status),
                                (unsigned long)NULL,
                                VM_PKT_DATA_INBAND, 0);

}

static void free_balloon_pages(struct hv_dynmem_device *dm,
                         union dm_mem_page_range *range_array)
{
        int num_pages = range_array->finfo.page_cnt;
        __u64 start_frame = range_array->finfo.start_page;
        struct page *pg;
        int i;

        for (i = 0; i < num_pages; i++) {
                pg = pfn_to_page(i + start_frame);
                __free_page(pg);
                dm->num_pages_ballooned--;
        }
}



static int  alloc_balloon_pages(struct hv_dynmem_device *dm, int num_pages,
                         struct dm_balloon_response *bl_resp, int alloc_unit,
                         bool *alloc_error)
{
        int i = 0;
        struct page *pg;

        if (num_pages < alloc_unit)
                return 0;

        for (i = 0; (i * alloc_unit) < num_pages; i++) {
                if (bl_resp->hdr.size + sizeof(union dm_mem_page_range) >
                        PAGE_SIZE)
                        return i * alloc_unit;

                /*
                 * We execute this code in a thread context. Furthermore,
                 * we don't want the kernel to try too hard.
                 */
                pg = alloc_pages(GFP_HIGHUSER | __GFP_NORETRY |
                                __GFP_NOMEMALLOC | __GFP_NOWARN,
                                get_order(alloc_unit << PAGE_SHIFT));

                if (!pg) {
                        *alloc_error = true;
                        return i * alloc_unit;
                }


                dm->num_pages_ballooned += alloc_unit;

                bl_resp->range_count++;
                bl_resp->range_array[i].finfo.start_page =
                        page_to_pfn(pg);
                bl_resp->range_array[i].finfo.page_cnt = alloc_unit;
                bl_resp->hdr.size += sizeof(union dm_mem_page_range);

        }

        return num_pages;
}



static void balloon_up(struct hv_dynmem_device *dm, struct dm_balloon *req)
{
        int num_pages = req->num_pages;
        int num_ballooned = 0;
        struct dm_balloon_response *bl_resp;
        int alloc_unit;
        int ret;
        bool alloc_error = false;
        bool done = false;
        int i;


        /*
         * Currently, we only support 4k allocations.
         */
        alloc_unit = 1;

        while (!done) {
                bl_resp = (struct dm_balloon_response *)send_buffer;
                memset(send_buffer, 0, PAGE_SIZE);
                bl_resp->hdr.type = DM_BALLOON_RESPONSE;
                bl_resp->hdr.trans_id = atomic_inc_return(&trans_id);
                bl_resp->hdr.size = sizeof(struct dm_balloon_response);
                bl_resp->more_pages = 1;


                num_pages -= num_ballooned;
                num_ballooned = alloc_balloon_pages(dm, num_pages,
                                                bl_resp, alloc_unit,
                                                 &alloc_error);

                if ((alloc_error) || (num_ballooned == num_pages)) {
                        bl_resp->more_pages = 0;
                        done = true;
                        dm->state = DM_INITIALIZED;
                }

                /*
                 * We are pushing a lot of data through the channel;
                 * deal with transient failures caused because of the
                 * lack of space in the ring buffer.
                 */

                do {
                        ret = vmbus_sendpacket(dm_device.dev->channel,
                                                bl_resp,
                                                bl_resp->hdr.size,
                                                (unsigned long)NULL,
                                                VM_PKT_DATA_INBAND, 0);

                        if (ret == -EAGAIN)
                                msleep(20);

                } while (ret == -EAGAIN);

                if (ret) {
                        /*
                         * Free up the memory we allocatted.
                         */
                        pr_info("Balloon response failed\n");

                        for (i = 0; i < bl_resp->range_count; i++)
                                free_balloon_pages(dm,
                                                 &bl_resp->range_array[i]);

                        done = true;
                }
        }

}

static void balloon_down(struct hv_dynmem_device *dm,
                        struct dm_unballoon_request *req)
{
        union dm_mem_page_range *range_array = req->range_array;
        int range_count = req->range_count;
        struct dm_unballoon_response resp;
        int i;

        for (i = 0; i < range_count; i++)
                free_balloon_pages(dm, &range_array[i]);

        if (req->more_pages == 1)
                return;

        memset(&resp, 0, sizeof(struct dm_unballoon_response));
        resp.hdr.type = DM_UNBALLOON_RESPONSE;
        resp.hdr.trans_id = atomic_inc_return(&trans_id);
        resp.hdr.size = sizeof(struct dm_unballoon_response);

        vmbus_sendpacket(dm_device.dev->channel, &resp,
                                sizeof(struct dm_unballoon_response),
                                (unsigned long)NULL,
                                VM_PKT_DATA_INBAND, 0);

        dm->state = DM_INITIALIZED;
}

static void balloon_onchannelcallback(void *context);

static int dm_thread_func(void *dm_dev)
{
        struct hv_dynmem_device *dm = dm_dev;
        int t;
        unsigned long  scan_start;

        while (!kthread_should_stop()) {
                t = wait_for_completion_timeout(&dm_device.config_event, 1*HZ);
                /*
                 * The host expects us to post information on the memory
                 * pressure every second.
                 */

                if (t == 0)
                        post_status(dm);

                scan_start = jiffies;
                switch (dm->state) {
                case DM_BALLOON_UP:
                        balloon_up(dm, (struct dm_balloon *)recv_buffer);
                        break;

                case DM_HOT_ADD:
                        hot_add_req(dm, (struct dm_hot_add *)recv_buffer);
                        break;
                default:
                        break;
                }

                if (!time_in_range(jiffies, scan_start, scan_start + HZ))
                        post_status(dm);

        }

        return 0;
}


static void version_resp(struct hv_dynmem_device *dm,
                        struct dm_version_response *vresp)
{
        struct dm_version_request version_req;
        int ret;

        if (vresp->is_accepted) {
                /*
                 * We are done; wakeup the
                 * context waiting for version
                 * negotiation.
                 */
                complete(&dm->host_event);
                return;
        }
        /*
         * If there are more versions to try, continue
         * with negotiations; if not
         * shutdown the service since we are not able
         * to negotiate a suitable version number
         * with the host.
         */
        if (dm->next_version == 0)
                goto version_error;

        dm->next_version = 0;
        memset(&version_req, 0, sizeof(struct dm_version_request));
        version_req.hdr.type = DM_VERSION_REQUEST;
        version_req.hdr.size = sizeof(struct dm_version_request);
        version_req.hdr.trans_id = atomic_inc_return(&trans_id);
        version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN7;
        version_req.is_last_attempt = 1;

        ret = vmbus_sendpacket(dm->dev->channel, &version_req,
                                sizeof(struct dm_version_request),
                                (unsigned long)NULL,
                                VM_PKT_DATA_INBAND, 0);

        if (ret)
                goto version_error;

        return;

version_error:
        dm->state = DM_INIT_ERROR;
        complete(&dm->host_event);
}

static void cap_resp(struct hv_dynmem_device *dm,
                        struct dm_capabilities_resp_msg *cap_resp)
{
        if (!cap_resp->is_accepted) {
                pr_info("Capabilities not accepted by host\n");
                dm->state = DM_INIT_ERROR;
        }
        complete(&dm->host_event);
}

static void balloon_onchannelcallback(void *context)
{
        struct hv_device *dev = context;
        u32 recvlen;
        u64 requestid;
        struct dm_message *dm_msg;
        struct dm_header *dm_hdr;
        struct hv_dynmem_device *dm = hv_get_drvdata(dev);

        memset(recv_buffer, 0, sizeof(recv_buffer));
        vmbus_recvpacket(dev->channel, recv_buffer,
                         PAGE_SIZE, &recvlen, &requestid);

        if (recvlen > 0) {
                dm_msg = (struct dm_message *)recv_buffer;
                dm_hdr = &dm_msg->hdr;

                switch (dm_hdr->type) {
                case DM_VERSION_RESPONSE:
                        version_resp(dm,
                                 (struct dm_version_response *)dm_msg);
                        break;

                case DM_CAPABILITIES_RESPONSE:
                        cap_resp(dm,
                                 (struct dm_capabilities_resp_msg *)dm_msg);
                        break;

                case DM_BALLOON_REQUEST:
                        dm->state = DM_BALLOON_UP;
                        complete(&dm->config_event);
                        break;

                case DM_UNBALLOON_REQUEST:
                        dm->state = DM_BALLOON_DOWN;
                        balloon_down(dm,
                                 (struct dm_unballoon_request *)recv_buffer);
                        break;

                case DM_MEM_HOT_ADD_REQUEST:
                        dm->state = DM_HOT_ADD;
                        complete(&dm->config_event);
                        break;

                case DM_INFO_MESSAGE:
                        process_info(dm, (struct dm_info_msg *)dm_msg);
                        break;

                default:
                        pr_err("Unhandled message: type: %d\n", dm_hdr->type);

                }
        }

}

static int balloon_probe(struct hv_device *dev,
                        const struct hv_vmbus_device_id *dev_id)
{
        int ret, t;
        struct dm_version_request version_req;
        struct dm_capabilities cap_msg;

        do_hot_add = hot_add;

        /*
         * First allocate a send buffer.
         */

        send_buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!send_buffer)
                return -ENOMEM;

        ret = vmbus_open(dev->channel, dm_ring_size, dm_ring_size, NULL, 0,
                        balloon_onchannelcallback, dev);

        if (ret)
                goto probe_error0;

        dm_device.dev = dev;
        dm_device.state = DM_INITIALIZING;
        dm_device.next_version = DYNMEM_PROTOCOL_VERSION_WIN7;
        init_completion(&dm_device.host_event);
        init_completion(&dm_device.config_event);

        dm_device.thread =
                 kthread_run(dm_thread_func, &dm_device, "hv_balloon");
        if (IS_ERR(dm_device.thread)) {
                ret = PTR_ERR(dm_device.thread);
                goto probe_error1;
        }

        hv_set_drvdata(dev, &dm_device);
        /*
         * Initiate the hand shake with the host and negotiate
         * a version that the host can support. We start with the
         * highest version number and go down if the host cannot
         * support it.
         */
        memset(&version_req, 0, sizeof(struct dm_version_request));
        version_req.hdr.type = DM_VERSION_REQUEST;
        version_req.hdr.size = sizeof(struct dm_version_request);
        version_req.hdr.trans_id = atomic_inc_return(&trans_id);
        version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN8;
        version_req.is_last_attempt = 0;

        ret = vmbus_sendpacket(dev->channel, &version_req,
                                sizeof(struct dm_version_request),
                                (unsigned long)NULL,
                                VM_PKT_DATA_INBAND,
                                VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
        if (ret)
                goto probe_error2;

        t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
        if (t == 0) {
                ret = -ETIMEDOUT;
                goto probe_error2;
        }

        /*
         * If we could not negotiate a compatible version with the host
         * fail the probe function.
         */
        if (dm_device.state == DM_INIT_ERROR) {
                ret = -ETIMEDOUT;
                goto probe_error2;
        }
        /*
         * Now submit our capabilities to the host.
         */
        memset(&cap_msg, 0, sizeof(struct dm_capabilities));
        cap_msg.hdr.type = DM_CAPABILITIES_REPORT;
        cap_msg.hdr.size = sizeof(struct dm_capabilities);
        cap_msg.hdr.trans_id = atomic_inc_return(&trans_id);

        cap_msg.caps.cap_bits.balloon = 1;
        /*
         * While we currently don't support hot-add,
         * we still advertise this capability since the
         * host requires that guests partcipating in the
         * dynamic memory protocol support hot add.
         */
        cap_msg.caps.cap_bits.hot_add = 1;

        /*
         * Currently the host does not use these
         * values and we set them to what is done in the
         * Windows driver.
         */
        cap_msg.min_page_cnt = 0;
        cap_msg.max_page_number = -1;

        ret = vmbus_sendpacket(dev->channel, &cap_msg,
                                sizeof(struct dm_capabilities),
                                (unsigned long)NULL,
                                VM_PKT_DATA_INBAND,
                                VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED);
        if (ret)
                goto probe_error2;

        t = wait_for_completion_timeout(&dm_device.host_event, 5*HZ);
        if (t == 0) {
                ret = -ETIMEDOUT;
                goto probe_error2;
        }

        /*
         * If the host does not like our capabilities,
         * fail the probe function.
         */
        if (dm_device.state == DM_INIT_ERROR) {
                ret = -ETIMEDOUT;
                goto probe_error2;
        }

        dm_device.state = DM_INITIALIZED;

        return 0;

probe_error2:
        kthread_stop(dm_device.thread);

probe_error1:
        vmbus_close(dev->channel);
probe_error0:
        kfree(send_buffer);
        return ret;
}

static int balloon_remove(struct hv_device *dev)
{
        struct hv_dynmem_device *dm = hv_get_drvdata(dev);

        if (dm->num_pages_ballooned != 0)
                pr_warn("Ballooned pages: %d\n", dm->num_pages_ballooned);

        vmbus_close(dev->channel);
        kthread_stop(dm->thread);
        kfree(send_buffer);

        return 0;
}

static const struct hv_vmbus_device_id id_table[] = {
        /* Dynamic Memory Class ID */
        /* 525074DC-8985-46e2-8057-A307DC18A502 */
        { HV_DM_GUID, },
        { },
};

MODULE_DEVICE_TABLE(vmbus, id_table);

static  struct hv_driver balloon_drv = {
        .name = "hv_balloon",
        .id_table = id_table,
        .probe =  balloon_probe,
        .remove =  balloon_remove,
};

static int __init init_balloon_drv(void)
{

        return vmbus_driver_register(&balloon_drv);
}

static void exit_balloon_drv(void)
{

        vmbus_driver_unregister(&balloon_drv);
}

module_init(init_balloon_drv);
module_exit(exit_balloon_drv);

MODULE_DESCRIPTION("Hyper-V Balloon");
MODULE_VERSION(HV_DRV_VERSION);
MODULE_LICENSE("GPL");