path: root/drivers/misc/vmw_balloon.c

/*
 * VMware Balloon driver.
 *
 * Copyright (C) 2000-2014, VMware, Inc. All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; version 2 of the License and no later version.
 *
 * 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.
 *
 * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Maintained by:	Xavier Deguillard <xdeguillard@vmware.com>
 *			Philip Moltmann <moltmann@vmware.com>
 */

/*
 * This is VMware physical memory management driver for Linux. The driver
 * acts like a "balloon" that can be inflated to reclaim physical pages by
 * reserving them in the guest and invalidating them in the monitor,
 * freeing up the underlying machine pages so they can be allocated to
 * other guests.  The balloon can also be deflated to allow the guest to
 * use more physical memory. Higher level policies can control the sizes
 * of balloons in VMs in order to manage physical memory resources.
 */

//#define DEBUG
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/vmw_vmci_defs.h>
#include <linux/vmw_vmci_api.h>
#include <asm/hypervisor.h>

MODULE_AUTHOR("VMware, Inc.");
MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
MODULE_VERSION("1.5.0.0-k");
MODULE_ALIAS("dmi:*:svnVMware*:*");
MODULE_ALIAS("vmware_vmmemctl");
MODULE_LICENSE("GPL");

/*
 * Various constants controlling rate of inflaint/deflating balloon,
 * measured in pages.
 */

/*
 * Rates of memory allocaton when guest experiences memory pressure
 * (driver performs sleeping allocations).
 */
#define VMW_BALLOON_RATE_ALLOC_MIN	512U
#define VMW_BALLOON_RATE_ALLOC_MAX	2048U
#define VMW_BALLOON_RATE_ALLOC_INC	16U

/*
 * When guest is under memory pressure, use a reduced page allocation
 * rate for next several cycles.
 */
#define VMW_BALLOON_SLOW_CYCLES		4

/*
 * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't
 * allow wait (__GFP_RECLAIM) for NOSLEEP page allocations. Use
 * __GFP_NOWARN, to suppress page allocation failure warnings.
 */
#define VMW_PAGE_ALLOC_NOSLEEP		(__GFP_HIGHMEM|__GFP_NOWARN)

/*
 * Use GFP_HIGHUSER when executing in a separate kernel thread
 * context and allocation can sleep.  This is less stressful to
 * the guest memory system, since it allows the thread to block
 * while memory is reclaimed, and won't take pages from emergency
 * low-memory pools.
 */
#define VMW_PAGE_ALLOC_CANSLEEP		(GFP_HIGHUSER)

/* Maximum number of refused pages we accumulate during inflation cycle */
#define VMW_BALLOON_MAX_REFUSED		16

/*
 * Hypervisor communication port definitions.
 */
#define VMW_BALLOON_HV_PORT		0x5670
#define VMW_BALLOON_HV_MAGIC		0x456c6d6f
#define VMW_BALLOON_GUEST_ID		1	/* Linux */

enum vmwballoon_capabilities {
	/*
	 * Bit 0 is reserved and not associated to any capability.
	 */
	VMW_BALLOON_BASIC_CMDS			= (1 << 1),
	VMW_BALLOON_BATCHED_CMDS		= (1 << 2),
	VMW_BALLOON_BATCHED_2M_CMDS		= (1 << 3),
	VMW_BALLOON_SIGNALLED_WAKEUP_CMD	= (1 << 4),
};

#define VMW_BALLOON_CAPABILITIES	(VMW_BALLOON_BASIC_CMDS \
					| VMW_BALLOON_BATCHED_CMDS \
					| VMW_BALLOON_BATCHED_2M_CMDS \
					| VMW_BALLOON_SIGNALLED_WAKEUP_CMD)

#define VMW_BALLOON_2M_SHIFT		(9)
#define VMW_BALLOON_NUM_PAGE_SIZES	(2)

/*
 * Backdoor commands availability:
 *
 * START, GET_TARGET and GUEST_ID are always available,
 *
 * VMW_BALLOON_BASIC_CMDS:
 *	LOCK and UNLOCK commands,
 * VMW_BALLOON_BATCHED_CMDS:
 *	BATCHED_LOCK and BATCHED_UNLOCK commands.
 * VMW BALLOON_BATCHED_2M_CMDS:
 *	BATCHED_2M_LOCK and BATCHED_2M_UNLOCK commands,
 * VMW VMW_BALLOON_SIGNALLED_WAKEUP_CMD:
 *	VMW_BALLOON_CMD_VMCI_DOORBELL_SET command.
 */
#define VMW_BALLOON_CMD_START			0
#define VMW_BALLOON_CMD_GET_TARGET		1
#define VMW_BALLOON_CMD_LOCK			2
#define VMW_BALLOON_CMD_UNLOCK			3
#define VMW_BALLOON_CMD_GUEST_ID		4
#define VMW_BALLOON_CMD_BATCHED_LOCK		6
#define VMW_BALLOON_CMD_BATCHED_UNLOCK		7
#define VMW_BALLOON_CMD_BATCHED_2M_LOCK		8
#define VMW_BALLOON_CMD_BATCHED_2M_UNLOCK	9
#define VMW_BALLOON_CMD_VMCI_DOORBELL_SET	10


/* error codes */
#define VMW_BALLOON_SUCCESS		        0
#define VMW_BALLOON_FAILURE		        -1
#define VMW_BALLOON_ERROR_CMD_INVALID	        1
#define VMW_BALLOON_ERROR_PPN_INVALID	        2
#define VMW_BALLOON_ERROR_PPN_LOCKED	        3
#define VMW_BALLOON_ERROR_PPN_UNLOCKED	        4
#define VMW_BALLOON_ERROR_PPN_PINNED	        5
#define VMW_BALLOON_ERROR_PPN_NOTNEEDED	        6
#define VMW_BALLOON_ERROR_RESET		        7
#define VMW_BALLOON_ERROR_BUSY		        8

#define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES	(0x03000000)

/* Batch page description */

/*
 * Layout of a page in the batch page:
 *
 * +-------------+----------+--------+
 * |             |          |        |
 * | Page number | Reserved | Status |
 * |             |