path: root/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.