path: root/drivers/misc/vmw_balloon.c

// SPDX-License-Identifier: GPL-2.0
/*
 * VMware Balloon driver.
 *
 * Copyright (C) 2000-2018, VMware, Inc. All Rights Reserved.
 *
 * 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/rwsem.h>
#include <linux/slab.h>
#include <linux/spinlock.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");

/*
 * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We don't allow wait
 * (__GFP_RECLAIM) for huge page allocations. Use __GFP_NOWARN, to suppress page
 * allocation failure warnings. Disallow access to emergency low-memory pools.
 */
#define VMW_HUGE_PAGE_ALLOC_FLAGS	(__GFP_HIGHMEM|__GFP_NOWARN|	\
					 __GFP_NOMEMALLOC)

/*
 * Use __GFP_HIGHMEM to allow pages from HIGHMEM zone. We allow lightweight
 * reclamation (__GFP_NORETRY). Use __GFP_NOWARN, to suppress page allocation
 * failure warnings. Disallow access to emergency low-memory pools.
 */
#define VMW_PAGE_ALLOC_FLAGS		(__GFP_HIGHMEM|__GFP_NOWARN|	\
					 __GFP_NOMEMALLOC|__GFP_NORETRY)

/* 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_ORDER		(PMD_SHIFT - PAGE_SHIFT)

enum vmballoon_page_size_type {
	VMW_BALLOON_4K_PAGE,
	VMW_BALLOON_2M_PAGE,
	VMW_BALLOON_LAST_SIZE = VMW_BALLOON_2M_PAGE
};

#define VMW_BALLOON_NUM_PAGE_SIZES	(VMW_BALLOON_LAST_SIZE + 1)

static const char * const vmballoon_page_size_names[] = {
	[VMW_BALLOON_4K_PAGE]			= "4k",
	[VMW_BALLOON_2M_PAGE]			= "2M"
};

enum vmballoon_op {
	VMW_BALLOON_INFLATE,
	VMW_BALLOON_DEFLATE
};

enum vmballoon_op_stat_type {
	VMW_BALLOON_OP_STAT,
	VMW_BALLOON_OP_FAIL_STAT
};

#define VMW_BALLOON_OP_STAT_TYPES	(VMW_BALLOON_OP_FAIL_STAT + 1)

/**
 * enum vmballoon_cmd_type - backdoor commands.
 *
 * Availability of the commands is as followed:
 *
 * %VMW_BALLOON_CMD_START, %VMW_BALLOON_CMD_GET_TARGET and
 * %VMW_BALLOON_CMD_GUEST_ID are always available.
 *
 * If the host reports %VMW_BALLOON_BASIC_CMDS are supported then
 * %VMW_BALLOON_CMD_LOCK and %VMW_BALLOON_CMD_UNLOCK commands are available.
 *
 * If the host reports %VMW_BALLOON_BATCHED_CMDS are supported then
 * %VMW_BALLOON_CMD_BATCHED_LOCK and VMW_BALLOON_CMD_BATCHED_UNLOCK commands
 * are available.
 *
 * If the host reports %VMW_BALLOON_BATCHED_2M_CMDS are supported then
 * %VMW_BALLOON_CMD_BATCHED_2M_LOCK and %VMW_BALLOON_CMD_BATCHED_2M_UNLOCK
 * are supported.
 *
 * If the host reports  VMW_BALLOON_SIGNALLED_WAKEUP_CMD is supported then
 * VMW_BALLOON_CMD_VMCI_DOORBELL_SET command is supported.
 *
 * @VMW_BALLOON_CMD_START: Communicating supported version with the hypervisor.
 * @VMW_BALLOON_CMD_GET_TARGET: Gets the balloon target size.
 * @VMW_BALLOON_CMD_LOCK: Informs the hypervisor about a ballooned page.
 * @VMW_BALLOON_CMD_UNLOCK: Informs the hypervisor about a page that is about
 *			    to be deflated from the balloon.
 * @VMW_BALLOON_CMD_GUEST_ID: Informs the hypervisor about the type of OS that
 *			      runs in the VM.
 * @VMW_BALLOON_CMD_BATCHED_LOCK: Inform the hypervisor about a batch of
 *				  ballooned pages (up to 512).
 * @VMW_BALLOON_CMD_BATCHED_UNLOCK: Inform the hypervisor about a batch of
 *				  pages that are about to be deflated from the
 *				  balloon (up to 512).
 * @VMW_BALLOON_CMD_BATCHED_2M_LOCK: Similar to @VMW_BALLOON_CMD_BATCHED_LOCK
 *				     for 2MB pages.
 * @VMW_BALLOON_CMD_BATCHED_2M_UNLOCK: Similar to
 *				       @VMW_BALLOON_CMD_BATCHED_UNLOCK for 2MB
 *				       pages.
 * @VMW_BALLOON_CMD_VMCI_DOORBELL_SET: A command to set doorbell notification
 *				       that would be invoked when the balloon
 *				       size changes.
 * @VMW_BALLOON_CMD_LAST: Value of the last command.
 */
enum vmballoon_cmd_type {
	VMW_BALLOON_CMD_START,
	VMW_BALLOON_CMD_GET_TARGET,
	VMW_BALLOON_CMD_LOCK,
	VMW_BALLOON_CMD_UNLOCK,
	VMW_BALLOON_CMD_GUEST_ID,
	/* No command 5 */
	VMW_BALLOON_CMD_BATCHED_LOCK = 6,
	VMW_BALLOON_CMD_BATCHED_UNLOCK,
	VMW_BALLOON_CMD_BATCHED_2M_LOCK,
	VMW_BALLOON_CMD_BATCHED_2M_UNLOCK,
	VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
	VMW_BALLOON_CMD_LAST = VMW_BALLOON_CMD_VMCI_DOORBELL_SET,
};

#define VMW_BALLOON_CMD_NUM	(VMW_BALLOON_CMD_LAST + 1)

enum vmballoon_error_codes {
	VMW_BALLOON_SUCCESS,
	VMW_BALLOON_ERROR_CMD_INVALID,
	VMW_BALLOON_ERROR_PPN_INVALID,
	VMW_BALLOON_ERROR_PPN_LOCKED,
	VMW_BALLOON_ERROR_PPN_UNLOCKED,
	VMW_BALLOON_ERROR_PPN_PINNED,
	VMW_BALLOON_ERROR_PPN_NOTNEEDED,
	VMW_BALLOON_ERROR_RESET,
	VMW_BALLOON_ERROR_BUSY
};

#define VMW_BALLOON_SUCCESS_WITH_CAPABILITIES	(0x03000000)

#define VMW_BALLOON_CMD_WITH_TARGET_MASK			\
	((1UL << VMW_BALLOON_CMD_GET_TARGET)		|	\
	 (1UL << VMW_BALLOON_CMD_LOCK)			|	\
	 (1UL << VMW_BALLOON_CMD_UNLOCK)		|	\
	 (1UL << VMW_BALLOON_CMD_BATCHED_LOCK)		|	\
	 (1UL << VMW_BALLOON_CMD_BATCHED_UNLOCK)	|	\
	 (1UL << VMW_BALLOON_CMD_BATCHED_2M_LOCK)	|	\
	 (1UL << VMW_BALLOON_CMD_BATCHED_2M_UNLOCK))

static const char * const vmballo