[PATCH 9/9] VMware balloon: Enable notification via VMCI

Philip P. Moltmann
2015-04-14T17:30:46Z

Get notified immediately when a balloon target is set, instead of waiting for
up to one second.

The up-to 1 second gap could be long enough to cause swapping inside of the
VM that receives the VM.

Acked-by: Andy King <acking@vmware.com>
Signed-off-by: Xavier Deguillard <xdeguillard@vmware.com>
Tested-by: Siva Sankar Reddy B <sankars@vmware.com>
---
drivers/misc/Kconfig | 2 +-
drivers/misc/vmw_balloon.c | 105 +++++++++++++++++++++++++++++++++++++++++----
2 files changed, 97 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 006242c..1c075b7 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -404,7 +404,7 @@ config TI_DAC7512

config VMWARE_BALLOON
tristate "VMware Balloon Driver"
- depends on X86 && HYPERVISOR_GUEST
+ depends on VMWARE_VMCI && X86 && HYPERVISOR_GUEST
help
This is VMware physical memory management driver which acts
like a "balloon" that can be inflated to reclaim physical pages
diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 861d9f3..53d951d 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -1,7 +1,7 @@
/*
* VMware Balloon driver.
*
- * Copyright (C) 2000-2013, VMware, Inc. All Rights Reserved.
+ * 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
@@ -42,11 +42,13 @@
#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("1.4.1.0-k");
+MODULE_VERSION("1.5.0.0-k");
MODULE_ALIAS("dmi:*:svnVMware*:*");
MODULE_ALIAS("vmware_vmmemctl");
MODULE_LICENSE("GPL");
@@ -100,14 +102,16 @@ 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_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_BATCHED_2M_CMDS \
+ | VMW_BALLOON_SIGNALLED_WAKEUP_CMD)

#define VMW_BALLOON_2M_SHIFT (9)
#define VMW_BALLOON_NUM_PAGE_SIZES (2)
@@ -122,7 +126,9 @@ enum vmwballoon_capabilities {
* VMW_BALLOON_BATCHED_CMDS:
* BATCHED_LOCK and BATCHED_UNLOCK commands.
* VMW BALLOON_BATCHED_2M_CMDS:
- * BATCHED_2M_LOCK and BATCHED_2M_UNLOCK commands.
+ * 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
@@ -133,6 +139,7 @@ enum vmwballoon_capabilities {
#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 */
@@ -213,6 +220,7 @@ static void vmballoon_batch_set_pa(struct vmballoon_batch_page *batch, int idx,
#ifdef CONFIG_DEBUG_FS
struct vmballoon_stats {
unsigned int timer;
+ unsigned int doorbell;

/* allocation statistics */
unsigned int alloc[VMW_BALLOON_NUM_PAGE_SIZES];
@@ -234,6 +242,8 @@ struct vmballoon_stats {
unsigned int start_fail;
unsigned int guest_type;
unsigned int guest_type_fail;
+ unsigned int doorbell_set;
+ unsigned int doorbell_unset;
};

#define STATS_INC(stat) (stat)++
@@ -298,6 +308,8 @@ struct vmballoon {
struct sysinfo sysinfo;

struct delayed_work dwork;
+
+ struct vmci_handle vmci_doorbell;
};

static struct vmballoon balloon;
@@ -992,12 +1004,75 @@ static bool vmballoon_init_batching(struct vmballoon *b)
}

/*
+ * Receive notification and resize balloon
+ */
+static void vmballoon_doorbell(void *client_data)
+{
+ struct vmballoon *b = client_data;
+
+ STATS_INC(b->stats.doorbell);
+
+ mod_delayed_work(system_freezable_wq, &b->dwork, 0);
+}
+
+/*
+ * Clean up vmci doorbell
+ */
+static void vmballoon_vmci_cleanup(struct vmballoon *b)
+{
+ int error;
+
+ VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET, VMCI_INVALID_ID,
+ VMCI_INVALID_ID, error);
+ STATS_INC(b->stats.doorbell_unset);
+
+ if (!vmci_handle_is_invalid(b->vmci_doorbell)) {
+ vmci_doorbell_destroy(b->vmci_doorbell);
+ b->vmci_doorbell = VMCI_INVALID_HANDLE;
+ }
+}
+
+/*
+ * Initialize vmci doorbell, to get notified as soon as balloon changes
+ */
+static int vmballoon_vmci_init(struct vmballoon *b)
+{
+ int error = 0;
+
+ if ((b->capabilities & VMW_BALLOON_SIGNALLED_WAKEUP_CMD) != 0) {
+ error = vmci_doorbell_create(&b->vmci_doorbell,
+ VMCI_FLAG_DELAYED_CB,
+ VMCI_PRIVILEGE_FLAG_RESTRICTED,
+ vmballoon_doorbell, b);
+
+ if (error == VMCI_SUCCESS) {
+ VMWARE_BALLOON_CMD(VMCI_DOORBELL_SET,
+ b->vmci_doorbell.context,
+ b->vmci_doorbell.resource, error);
+ STATS_INC(b->stats.doorbell_set);
+ }
+ }
+
+ if (error != 0) {
+ vmballoon_vmci_cleanup(b);
+
+ return -EIO;
+ }
+
+ return 0;
+}
+
+/*
* 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)
{
+ int error;
+
+ vmballoon_vmci_cleanup(b);
+
/* free all pages, skipping monitor unlock */
vmballoon_pop(b);

@@ -1023,6 +1098,11 @@ static void vmballoon_reset(struct vmballoon *b)
}

b->reset_required = false;
+
+ error = vmballoon_vmci_init(b);
+ if (error)
+ pr_err("failed to initialize vmci doorbell\n");
+
if (!vmballoon_send_guest_id(b))
pr_err("failed to send guest ID to the host\n");
}
@@ -1096,6 +1176,7 @@ static int vmballoon_debug_show(struct seq_file *f, void *offset)
seq_printf(f,
"\n"
"timer: %8u\n"
+ "doorbell: %8u\n"
"start: %8u (%4u failed)\n"
"guestType: %8u (%4u failed)\n"
"2m-lock: %8u (%4u failed)\n"
@@ -1111,8 +1192,11 @@ static int vmballoon_debug_show(struct seq_file *f, void *offset)
"err2mAlloc: %8u\n"
"errAlloc: %8u\n"
"err2mFree: %8u\n"
- "errFree: %8u\n",
+ "errFree: %8u\n"
+ "doorbellSet: %8u\n"
+ "doorbellUnset: %8u\n",
stats->timer,
+ stats->doorbell,
stats->start, stats->start_fail,
stats->guest_type, stats->guest_type_fail,
stats->lock[true], stats->lock_fail[true],
@@ -1126,7 +1210,8 @@ static int vmballoon_debug_show(struct seq_file *f, void *offset)
stats->free[true],
stats->free[false],
stats->refused_alloc[true], stats->refused_alloc[false],
- stats->refused_free[true], stats->refused_free[false]);
+ stats->refused_free[true], stats->refused_free[false],
+ stats->doorbell_set, stats->doorbell_unset);

return 0;
}
@@ -1203,6 +1288,7 @@ static int __init vmballoon_init(void)
if (error)
return error;

+ balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
balloon.batch_page = NULL;
balloon.page = NULL;
balloon.reset_required = true;
@@ -1215,6 +1301,7 @@ module_init(vmballoon_init);

static void __exit vmballoon_exit(void)
{
+ vmballoon_vmci_cleanup(&balloon);
cancel_delayed_work_sync(&balloon.dwork);

vmballoon_debugfs_exit(&balloon);
--
1.9.3