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Date: Wed, 21 Apr 2010 12:59:35 -0700
From: Dmitry Torokhov <dtor@...are.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"pv-drivers@...are.com" <pv-drivers@...are.com>,
Avi Kivity <avi@...hat.com>,
Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: [PATCH v2] VMware Balloon driver
On Thu, Apr 15, 2010 at 02:00:30PM -0700, Dmitry Torokhov wrote:
> This is standalone version of VMware Balloon driver. Ballooning is a
> technique that allows hypervisor dynamically limit the amount of memory
> available to the guest (with guest cooperation). In the overcommit
> scenario, when hypervisor set detects that it needs to shuffle some memory,
> it instructs the driver to allocate certain number of pages, and the
> underlying memory gets returned to the hypervisor. Later hypervisor may
> return memory to the guest by reattaching memory to the pageframes and
> instructing the driver to "deflate" balloon.
>
> Signed-off-by: Dmitry Torokhov <dtor@...are.com>
Andrew,
Do you see any issues with the driver? Will you be the one picking it
up and queueing for mainline?
Thanks,
Dmitry
> ---
>
> Unlike previous version, that tried to integrate VMware ballooning transport
> into virtio subsystem, and use stock virtio_ballon driver, this one implements
> both controlling thread/algorithm and hypervisor transport.
>
> We are submitting standalone driver because KVM maintainer (Avi Kivity)
> expressed opinion (rightly) that our transport does not fit well into
> virtqueue paradigm and thus it does not make much sense to integrate
> with virtio.
>
> There were also some concerns whether current ballooning technique is
> the right thing. If there appears a better framework to achieve this we
> are prepared to evaluate and switch to using it, but in the meantime
> we'd like to get this driver upstream.
>
> Changes since v1:
> - added comments throughout the code;
> - exported stats moved from /proc to debugfs;
> - better changelog.
>
> arch/x86/kernel/cpu/vmware.c | 2
> drivers/misc/Kconfig | 16 +
> drivers/misc/Makefile | 1
> drivers/misc/vmware_balloon.c | 808 +++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 827 insertions(+), 0 deletions(-)
> create mode 100644 drivers/misc/vmware_balloon.c
>
>
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index 1cbed97..dfdb4db 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -22,6 +22,7 @@
> */
>
> #include <linux/dmi.h>
> +#include <linux/module.h>
> #include <asm/div64.h>
> #include <asm/vmware.h>
> #include <asm/x86_init.h>
> @@ -101,6 +102,7 @@ int vmware_platform(void)
>
> return 0;
> }
> +EXPORT_SYMBOL(vmware_platform);
>
> /*
> * VMware hypervisor takes care of exporting a reliable TSC to the guest.
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 2191c8d..0d0d625 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -311,6 +311,22 @@ config TI_DAC7512
> This driver can also be built as a module. If so, the module
> will be calles ti_dac7512.
>
> +config VMWARE_BALLOON
> + tristate "VMware Balloon Driver"
> + depends on X86
> + help
> + This is VMware physical memory management driver which 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.
> +
> + If unsure, say N.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called vmware_balloon.
> +
> source "drivers/misc/c2port/Kconfig"
> source "drivers/misc/eeprom/Kconfig"
> source "drivers/misc/cb710/Kconfig"
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index 27c4843..7b6f7ee 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -29,3 +29,4 @@ obj-$(CONFIG_C2PORT) += c2port/
> obj-$(CONFIG_IWMC3200TOP) += iwmc3200top/
> obj-y += eeprom/
> obj-y += cb710/
> +obj-$(CONFIG_VMWARE_BALLOON) += vmware_balloon.o
> diff --git a/drivers/misc/vmware_balloon.c b/drivers/misc/vmware_balloon.c
> new file mode 100644
> index 0000000..90bba04
> --- /dev/null
> +++ b/drivers/misc/vmware_balloon.c
> @@ -0,0 +1,808 @@
> +/*
> + * VMware Balloon driver.
> + *
> + * Copyright (C) 2000-2010, 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: Dmitry Torokhov <dtor@...are.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/sched.h>
> +#include <linux/module.h>
> +#include <linux/workqueue.h>
> +#include <linux/debugfs.h>
> +#include <linux/seq_file.h>
> +#include <asm/vmware.h>
> +
> +MODULE_AUTHOR("VMware, Inc.");
> +MODULE_DESCRIPTION("VMware Memory Control (Balloon) Driver");
> +MODULE_VERSION("1.2.1.0-K");
> +MODULE_ALIAS("dmi:*:svnVMware*:*");
> +MODULE_ALIAS("vmware_vmmemctl");
> +MODULE_LICENSE("GPL");
> +
> +#define VMW_BALLOON_NOSLEEP_ALLOC_MAX 16384U
> +
> +#define VMW_BALLOON_RATE_ALLOC_MIN 512U
> +#define VMW_BALLOON_RATE_ALLOC_MAX 2048U
> +#define VMW_BALLOON_RATE_ALLOC_INC 16U
> +
> +#define VMW_BALLOON_RATE_FREE_MIN 512U
> +#define VMW_BALLOON_RATE_FREE_MAX 16384U
> +#define VMW_BALLOON_RATE_FREE_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_WAIT) 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 page allocations without yielding processor */
> +#define VMW_BALLOON_YIELD_THRESHOLD 1024
> +
> +#define VMW_BALLOON_HV_PORT 0x5670
> +#define VMW_BALLOON_HV_MAGIC 0x456c6d6f
> +#define VMW_BALLOON_PROTOCOL_VERSION 2
> +#define VMW_BALLOON_GUEST_ID 1 /* Linux */
> +
> +#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
> +
> +/* 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 VMWARE_BALLOON_CMD(cmd, data, result) \
> +({ \
> + unsigned long __stat, __dummy1, __dummy2; \
> + __asm__ __volatile__ ("inl (%%dx)" : \
> + "=a"(__stat), \
> + "=c"(__dummy1), \
> + "=d"(__dummy2), \
> + "=b"(result) : \
> + "0"(VMW_BALLOON_HV_MAGIC), \
> + "1"(VMW_BALLOON_CMD_##cmd), \
> + "2"(VMW_BALLOON_HV_PORT), \
> + "3"(data) : \
> + "memory"); \
> + result &= -1UL; \
> + __stat & -1UL; \
> +})
> +
> +#define STATS_INC(stat) (stat)++
> +
> +struct vmballoon_stats {
> + unsigned int timer;
> +
> + /* allocation statustics */
> + unsigned int alloc;
> + unsigned int alloc_fail;
> + unsigned int sleep_alloc;
> + unsigned int sleep_alloc_fail;
> + unsigned int refused_alloc;
> + unsigned int refused_free;
> + unsigned int free;
> +
> + /* monitor operations */
> + unsigned int lock;
> + unsigned int lock_fail;
> + unsigned int unlock;
> + unsigned int unlock_fail;
> + unsigned int target;
> + unsigned int target_fail;
> + unsigned int start;
> + unsigned int start_fail;
> + unsigned int guest_type;
> + unsigned int guest_type_fail;
> +};
> +
> +struct vmballoon {
> +
> + /* list of reserved physical pages */
> + struct list_head pages;
> +
> + /* transient list of non-balloonable pages */
> + struct list_head refused_pages;
> +
> + /* balloon size in pages */
> + unsigned int size;
> + unsigned int target;
> +
> + /* reset flag */
> + bool reset_required;
> +
> + /* adjustment rates (pages per second) */
> + unsigned int rate_alloc;
> + unsigned int rate_free;
> +
> + /* slowdown page allocations for next few cycles */
> + unsigned int slow_allocation_cycles;
> +
> + /* statistics */
> + struct vmballoon_stats stats;
> +
> + /* debugfs file exporting statistics */
> + struct dentry *dbg_entry;
> +
> + struct sysinfo sysinfo;
> +
> + struct delayed_work dwork;
> +};
> +
> +static struct vmballoon balloon;
> +static struct workqueue_struct *vmballoon_wq;
> +
> +/*
> + * Send "start" command to the host, communicating supported version
> + * of the protocol.
> + */
> +static bool vmballoon_send_start(struct vmballoon *b)
> +{
> + unsigned long status, dummy;
> +
> + STATS_INC(b->stats.start);
> +
> + status = VMWARE_BALLOON_CMD(START, VMW_BALLOON_PROTOCOL_VERSION, dummy);
> + if (status == VMW_BALLOON_SUCCESS)
> + return true;
> +
> + pr_debug("%s - failed, hv returns %ld\n", __func__, status);
> + STATS_INC(b->stats.start_fail);
> + return false;
> +}
> +
> +static bool vmballoon_check_status(struct vmballoon *b, unsigned long status)
> +{
> + switch (status) {
> + case VMW_BALLOON_SUCCESS:
> + return true;
> +
> + case VMW_BALLOON_ERROR_RESET:
> + b->reset_required = true;
> + /* fall through */
> +
> + default:
> + return false;
> + }
> +}
> +
> +/*
> + * Communicate guest type to the host so that it can adjust ballooning
> + * algorithm to the one most appropriate for the guest. This command
> + * is normally issued after sending "start" command and is part of
> + * standard reset sequence.
> + */
> +static bool vmballoon_send_guest_id(struct vmballoon *b)
> +{
> + unsigned long status, dummy;
> +
> + status = VMWARE_BALLOON_CMD(GUEST_ID, VMW_BALLOON_GUEST_ID, dummy);
> +
> + STATS_INC(b->stats.guest_type);
> +
> + if (vmballoon_check_status(b, status))
> + return true;
> +
> + pr_debug("%s - failed, hv returns %ld\n", __func__, status);
> + STATS_INC(b->stats.guest_type_fail);
> + return false;
> +}
> +
> +/*
> + * Retrieve desired balloon size from the host.
> + */
> +static bool vmballoon_send_get_target(struct vmballoon *b, u32 *new_target)
> +{
> + unsigned long status;
> + unsigned long target;
> + unsigned long limit;
> + u32 limit32;
> +
> + /*
> + * si_meminfo() is cheap. Moreover, we want to provide dynamic
> + * max balloon size later. So let us call si_meminfo() every
> + * iteration.
> + */
> + si_meminfo(&b->sysinfo);
> + limit = b->sysinfo.totalram;
> +
> + /* Ensure limit fits in 32-bits */
> + limit32 = (u32)limit;
> + if (limit != limit32)
> + return false;
> +
> + /* update stats */
> + STATS_INC(b->stats.target);
> +
> + status = VMWARE_BALLOON_CMD(GET_TARGET, limit, target);
> + if (vmballoon_check_status(b, status)) {
> + *new_target = target;
> + return true;
> + }
> +
> + pr_debug("%s - failed, hv returns %ld\n", __func__, status);
> + STATS_INC(b->stats.target_fail);
> + return false;
> +}
> +
> +/*
> + * Notify the host about allocated page so that host can use it without
> + * fear that guest will need it. Host may reject some pages, we need to
> + * check the return value and maybe submit a different page.
> + */
> +static bool vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn)
> +{
> + unsigned long status, dummy;
> + u32 pfn32;
> +
> + pfn32 = (u32)pfn;
> + if (pfn32 != pfn)
> + return false;
> +
> + STATS_INC(b->stats.lock);
> +
> + status = VMWARE_BALLOON_CMD(LOCK, pfn, dummy);
> + if (vmballoon_check_status(b, status))
> + return true;
> +
> + pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
> + STATS_INC(b->stats.lock_fail);
> + return false;
> +}
> +
> +/*
> + * Notify the host that guest intends to release given page back into
> + * the pool of available (to the guest) pages.
> + */
> +static bool vmballoon_send_unlock_page(struct vmballoon *b, unsigned long pfn)
> +{
> + unsigned long status, dummy;
> + u32 pfn32;
> +
> + pfn32 = (u32)pfn;
> + if (pfn32 != pfn)
> + return false;
> +
> + STATS_INC(b->stats.unlock);
> +
> + status = VMWARE_BALLOON_CMD(UNLOCK, pfn, dummy);
> + if (vmballoon_check_status(b, status))
> + return true;
> +
> + pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
> + STATS_INC(b->stats.unlock_fail);
> + return false;
> +}
> +
> +/*
> + * Quickly release all pages allocated for the balloon. This function is
> + * called when host decides to "reset" balloon for one reason or another.
> + * Unlike normal "deflate" we do not (shall not) notify host of the pages
> + * being released.
> + */
> +static void vmballoon_pop(struct vmballoon *b)
> +{
> + struct page *page, *next;
> + unsigned int count = 0;
> +
> + list_for_each_entry_safe(page, next, &b->pages, lru) {
> + list_del(&page->lru);
> + __free_page(page);
> + STATS_INC(b->stats.free);
> + b->size--;
> +
> + if (++count >= b->rate_free) {
> + count = 0;
> + cond_resched();
> + }
> + }
> +}
> +
> +/*
> + * Perform standard reset sequence by popping the balloon (in case it
> + * is not empty) and then restarting protocol. This operation normally
> + * happens when host responds with VMW_BALLOON_ERROR_RESET to a command.
> + */
> +static void vmballoon_reset(struct vmballoon *b)
> +{
> + /* free all pages, skipping monitor unlock */
> + vmballoon_pop(b);
> +
> + if (vmballoon_send_start(b)) {
> + b->reset_required = false;
> + if (!vmballoon_send_guest_id(b))
> + pr_err("failed to send guest ID to the host\n");
> + }
> +}
> +
> +/*
> + * Allocate (or reserve) a page for the balloon and notify the host. If host
> + * refuses the page put it on "refuse" list and allocate another one until host
> + * is satisfied. "Refused" pages are released at the end of inflation cycle
> + * (when we allocate b->rate_alloc pages).
> + */
> +static int vmballoon_reserve_page(struct vmballoon *b, bool can_sleep)
> +{
> + struct page *page;
> + gfp_t flags;
> + bool locked = false;
> +
> + do {
> + if (!can_sleep)
> + STATS_INC(b->stats.alloc);
> + else
> + STATS_INC(b->stats.sleep_alloc);
> +
> + flags = can_sleep ? VMW_PAGE_ALLOC_CANSLEEP : VMW_PAGE_ALLOC_NOSLEEP;
> + page = alloc_page(flags);
> + if (!page) {
> + if (!can_sleep)
> + STATS_INC(b->stats.alloc_fail);
> + else
> + STATS_INC(b->stats.sleep_alloc_fail);
> + return -ENOMEM;
> + }
> +
> + /* inform monitor */
> + locked = vmballoon_send_lock_page(b, page_to_pfn(page));
> + if (!locked) {
> + if (b->reset_required) {
> + __free_page(page);
> + return -EIO;
> + }
> +
> + /* place on list of non-balloonable pages, retry allocation */
> + list_add(&page->lru, &b->refused_pages);
> + STATS_INC(b->stats.refused_alloc);
> + }
> + } while (!locked);
> +
> + /* track allocated page */
> + list_add(&page->lru, &b->pages);
> +
> + /* update balloon size */
> + b->size++;
> +
> + return 0;
> +}
> +
> +/*
> + * Release the page allocated for the balloon. Note that we first notify
> + * the host so it can make sure the page will be available for the guest
> + * to use, if needed.
> + */
> +static int vmballoon_release_page(struct vmballoon *b, struct page *page)
> +{
> + if (!vmballoon_send_unlock_page(b, page_to_pfn(page)))
> + return -EIO;
> +
> + list_del(&page->lru);
> +
> + /* deallocate page */
> + __free_page(page);
> + STATS_INC(b->stats.free);
> +
> + /* update balloon size */
> + b->size--;
> +
> + return 0;
> +}
> +
> +/*
> + * Release pages that were allocated while attempting to inflate the
> + * balloon but were refused by the host for one reason or another.
> + */
> +static void vmballoon_release_refused_pages(struct vmballoon *b)
> +{
> + struct page *page, *next;
> +
> + list_for_each_entry_safe(page, next, &b->refused_pages, lru) {
> + list_del(&page->lru);
> + __free_page(page);
> + STATS_INC(b->stats.refused_free);
> + }
> +}
> +
> +/*
> + * Inflate the balloon towards its target size. Note that we try to limit
> + * the rate of allocation to make sure we are not choking the rest of the
> + * system.
> + */
> +static void vmballoon_inflate(struct vmballoon *b)
> +{
> + unsigned int goal;
> + unsigned int rate;
> + unsigned int i;
> + unsigned int allocations = 0;
> + int error = 0;
> + bool alloc_can_sleep = false;
> +
> + pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
> +
> + /*
> + * First try NOSLEEP page allocations to inflate balloon.
> + *
> + * If we do not throttle nosleep allocations, we can drain all
> + * free pages in the guest quickly (if the balloon target is high).
> + * As a side-effect, draining free pages helps to inform (force)
> + * the guest to start swapping if balloon target is not met yet,
> + * which is a desired behavior. However, balloon driver can consume
> + * all available CPU cycles if too many pages are allocated in a
> + * second. Therefore, we throttle nosleep allocations even when
> + * the guest is not under memory pressure. OTOH, if we have already
> + * predicted that the guest is under memory pressure, then we
> + * slowdown page allocations considerably.
> + */
> +
> + goal = b->target - b->size;
> + /*
> + * Start with no sleep allocation rate which may be higher
> + * than sleeping allocation rate.
> + */
> + rate = b->slow_allocation_cycles ?
> + b->rate_alloc : VMW_BALLOON_NOSLEEP_ALLOC_MAX;
> +
> + pr_debug("%s - goal: %d, no-sleep rate: %d, sleep rate: %d\n",
> + __func__, goal, rate, b->rate_alloc);
> +
> + for (i = 0; i < goal; i++) {
> +
> + error = vmballoon_reserve_page(b, alloc_can_sleep);
> + if (error) {
> + if (error != -ENOMEM) {
> + /*
> + * Not a page allocation failure, stop this
> + * cycle. Maybe we'll get new target from
> + * the host soon.
> + */
> + break;
> + }
> +
> + if (alloc_can_sleep) {
> + /*
> + * CANSLEEP page allocation failed, so guest
> + * is under severe memory pressure. Quickly
> + * decrease allocation rate.
> + */
> + b->rate_alloc = max(b->rate_alloc / 2,
> + VMW_BALLOON_RATE_ALLOC_MIN);
> + break;
> + }
> +
> + /*
> + * NOSLEEP page allocation failed, so the guest is
> + * under memory pressure. Let us slow down page
> + * allocations for next few cycles so that the guest
> + * gets out of memory pressure. Also, if we already
> + * allocated b->rate_alloc pages, let's pause,
> + * otherwise switch to sleeping allocations.
> + */
> + b->slow_allocation_cycles = VMW_BALLOON_SLOW_CYCLES;
> +
> + if (i >= b->rate_alloc)
> + break;
> +
> + alloc_can_sleep = true;
> + /* Lower rate for sleeping allocations. */
> + rate = b->rate_alloc;
> + }
> +
> + if (++allocations > VMW_BALLOON_YIELD_THRESHOLD) {
> + cond_resched();
> + allocations = 0;
> + }
> +
> + if (i >= rate) {
> + /* We allocated enough pages, let's take a break. */
> + break;
> + }
> + }
> +
> + /*
> + * We reached our goal without failures so try increasing
> + * allocation rate.
> + */
> + if (error == 0 && i >= b->rate_alloc) {
> + unsigned int mult = i / b->rate_alloc;
> +
> + b->rate_alloc =
> + min(b->rate_alloc + mult * VMW_BALLOON_RATE_ALLOC_INC,
> + VMW_BALLOON_RATE_ALLOC_MAX);
> + }
> +
> + vmballoon_release_refused_pages(b);
> +}
> +
> +/*
> + * Decrease the size of the balloon allowing guest to use more memory.
> + */
> +static void vmballoon_deflate(struct vmballoon *b)
> +{
> + struct page *page, *next;
> + unsigned int i = 0;
> + unsigned int goal;
> + int error;
> +
> + pr_debug("%s - size: %d, target %d\n", __func__, b->size, b->target);
> +
> + /* limit deallocation rate */
> + goal = min(b->size - b->target, b->rate_free);
> +
> + pr_debug("%s - goal: %d, rate: %d\n", __func__, goal, b->rate_free);
> +
> + /* free pages to reach target */
> + list_for_each_entry_safe(page, next, &b->pages, lru) {
> + error = vmballoon_release_page(b, page);
> + if (error) {
> + /* quickly decrease rate in case of error */
> + b->rate_free = max(b->rate_free / 2,
> + VMW_BALLOON_RATE_FREE_MIN);
> + return;
> + }
> +
> + if (++i >= goal)
> + break;
> + }
> +
> + /* slowly increase rate if there were no errors */
> + b->rate_free = min(b->rate_free + VMW_BALLOON_RATE_FREE_INC,
> + VMW_BALLOON_RATE_FREE_MAX);
> +}
> +
> +/*
> + * Balloon work function: reset protocol, if needed, get the new size and
> + * adjust balloon as needed. Repeat in 1 sec.
> + */
> +static void vmballoon_work(struct work_struct *work)
> +{
> + struct delayed_work *dwork = to_delayed_work(work);
> + struct vmballoon *b = container_of(dwork, struct vmballoon, dwork);
> + unsigned int target;
> +
> + STATS_INC(b->stats.timer);
> +
> + if (b->reset_required)
> + vmballoon_reset(b);
> +
> + if (b->slow_allocation_cycles > 0)
> + b->slow_allocation_cycles--;
> +
> + if (vmballoon_send_get_target(b, &target)) {
> + /* update target, adjust size */
> + b->target = target;
> +
> + if (b->size < target)
> + vmballoon_inflate(b);
> + else if (b->size > target)
> + vmballoon_deflate(b);
> + }
> +
> + queue_delayed_work(vmballoon_wq, dwork, round_jiffies_relative(HZ));
> +}
> +
> +/*
> + * PROCFS Interface
> + */
> +#ifdef CONFIG_DEBUG_FS
> +
> +static int vmballoon_debug_show(struct seq_file *f, void *offset)
> +{
> + struct vmballoon *b = f->private;
> + struct vmballoon_stats *stats = &b->stats;
> +
> + /* format size info */
> + seq_printf(f,
> + "target: %8d pages\n"
> + "current: %8d pages\n",
> + b->target, b->size);
> +
> + /* format rate info */
> + seq_printf(f,
> + "rateNoSleepAlloc: %8d pages/sec\n"
> + "rateSleepAlloc: %8d pages/sec\n"
> + "rateFree: %8d pages/sec\n",
> + VMW_BALLOON_NOSLEEP_ALLOC_MAX,
> + b->rate_alloc, b->rate_free);
> +
> + seq_printf(f,
> + "\n"
> + "timer: %8u\n"
> + "start: %8u (%4u failed)\n"
> + "guestType: %8u (%4u failed)\n"
> + "lock: %8u (%4u failed)\n"
> + "unlock: %8u (%4u failed)\n"
> + "target: %8u (%4u failed)\n"
> + "primNoSleepAlloc: %8u (%4u failed)\n"
> + "primCanSleepAlloc: %8u (%4u failed)\n"
> + "primFree: %8u\n"
> + "errAlloc: %8u\n"
> + "errFree: %8u\n",
> + stats->timer,
> + stats->start, stats->start_fail,
> + stats->guest_type, stats->guest_type_fail,
> + stats->lock, stats->lock_fail,
> + stats->unlock, stats->unlock_fail,
> + stats->target, stats->target_fail,
> + stats->alloc, stats->alloc_fail,
> + stats->sleep_alloc, stats->sleep_alloc_fail,
> + stats->free,
> + stats->refused_alloc, stats->refused_free);
> +
> + return 0;
> +}
> +
> +static int vmballoon_debug_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, vmballoon_debug_show, inode->i_private);
> +}
> +
> +static const struct file_operations vmballoon_debug_fops = {
> + .owner = THIS_MODULE,
> + .open = vmballoon_debug_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> +};
> +
> +static int __init vmballoon_debugfs_init(struct vmballoon *b)
> +{
> + int error;
> +
> + b->dbg_entry = debugfs_create_file("vmmemctl", S_IRUGO, NULL, b,
> + &vmballoon_debug_fops);
> + if (IS_ERR(b->dbg_entry)) {
> + error = PTR_ERR(b->dbg_entry);
> + pr_err("failed to create debugfs entry, error: %d\n", error);
> + return error;
> + }
> +
> + return 0;
> +}
> +
> +static void __exit vmballoon_debugfs_exit(struct vmballoon *b)
> +{
> + debugfs_remove(b->dbg_entry);
> +}
> +
> +#else
> +
> +static inline int vmballoon_debugfs_init(struct vmballoon *b)
> +{
> + return 0;
> +}
> +
> +static inline void vmballoon_debugfs_exit(void)
> +{
> +}
> +
> +#endif /* CONFIG_PROC_FS */
> +
> +static int __init vmballoon_init(void)
> +{
> + int error;
> +
> + /*
> + * Check if we are running on VMware's hypervisor and bail out
> + * if we are not.
> + */
> + if (!vmware_platform())
> + return -ENODEV;
> +
> + vmballoon_wq = create_freezeable_workqueue("vmmemctl");
> + if (!vmballoon_wq) {
> + pr_err("failed to create workqueue\n");
> + return -ENOMEM;
> + }
> +
> + /* initialize global state */
> + memset(&balloon, 0, sizeof(balloon));
> + INIT_LIST_HEAD(&balloon.pages);
> + INIT_LIST_HEAD(&balloon.refused_pages);
> +
> + /* initialize rates */
> + balloon.rate_alloc = VMW_BALLOON_RATE_ALLOC_MAX;
> + balloon.rate_free = VMW_BALLOON_RATE_FREE_MAX;
> +
> + INIT_DELAYED_WORK(&balloon.dwork, vmballoon_work);
> +
> + /*
> + * Start balloon.
> + */
> + if (!vmballoon_send_start(&balloon)) {
> + pr_err("failed to send start command to the host\n");
> + error = -EIO;
> + goto fail;
> + }
> +
> + if (!vmballoon_send_guest_id(&balloon)) {
> + pr_err("failed to send guest ID to the host\n");
> + error = -EIO;
> + goto fail;
> + }
> +
> + error = vmballoon_debugfs_init(&balloon);
> + if (error)
> + goto fail;
> +
> + queue_delayed_work(vmballoon_wq, &balloon.dwork, 0);
> +
> + return 0;
> +
> +fail:
> + destroy_workqueue(vmballoon_wq);
> + return error;
> +}
> +module_init(vmballoon_init);
> +
> +static void __exit vmballoon_exit(void)
> +{
> + cancel_delayed_work_sync(&balloon.dwork);
> + destroy_workqueue(vmballoon_wq);
> +
> + vmballoon_debugfs_exit(&balloon);
> +
> + /*
> + * Deallocate all reserved memory, and reset connection with monitor.
> + * Reset connection before deallocating memory to avoid potential for
> + * additional spurious resets from guest touching deallocated pages.
> + */
> + vmballoon_send_start(&balloon);
> + vmballoon_pop(&balloon);
> +}
> +module_exit(vmballoon_exit);
--
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