[PATCH 6/9] kvm tools: Add virtio-balloon device

[Sasha Levin <levinsasha928@gmail.com>]

>From the virtio spec:

The virtio memory balloon device is a primitive device for managing guest
memory: the device asks for a certain amount of memory, and the guest supplies
it (or withdraws it, if the device has more than it asks for). This allows the
guest to adapt to changes in allowance of underlying physical memory.

To activate the virtio-balloon device run kvm tools with the '--balloon'
command line parameter.

Current implementation listens for two signals:

 - SIGKVMADDMEM: Adds 1M to the balloon driver (inflate). This will decrease
available memory within the guest.
 - SIGKVMDELMEM: Remove 1M from the balloon driver (deflate). This will
increase available memory within the guest.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 tools/kvm/Makefile                     |    1 +
 tools/kvm/include/kvm/kvm.h            |    3 +
 tools/kvm/include/kvm/virtio-balloon.h |    8 +
 tools/kvm/include/kvm/virtio-pci-dev.h |    1 +
 tools/kvm/kvm-run.c                    |    6 +
 tools/kvm/virtio/balloon.c             |  265 ++++++++++++++++++++++++++++++++
 6 files changed, 284 insertions(+), 0 deletions(-)
 create mode 100644 tools/kvm/include/kvm/virtio-balloon.h
 create mode 100644 tools/kvm/virtio/balloon.c

diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile
index d368c22..a1b2f4c 100644
--- a/tools/kvm/Makefile
+++ b/tools/kvm/Makefile
@@ -40,6 +40,7 @@ OBJS	+= virtio/console.o
 OBJS	+= virtio/core.o
 OBJS	+= virtio/net.o
 OBJS	+= virtio/rng.o
+OBJS    += virtio/balloon.o
 OBJS	+= disk/blk.o
 OBJS	+= disk/qcow.o
 OBJS	+= disk/raw.o
diff --git a/tools/kvm/include/kvm/kvm.h b/tools/kvm/include/kvm/kvm.h
index 5ad3236..1fdfcf7 100644
--- a/tools/kvm/include/kvm/kvm.h
+++ b/tools/kvm/include/kvm/kvm.h
@@ -6,6 +6,7 @@
 #include <stdbool.h>
 #include <linux/types.h>
 #include <time.h>
+#include <signal.h>
 
 #define KVM_NR_CPUS		(255)
 
@@ -17,6 +18,8 @@
 
 #define SIGKVMEXIT		(SIGRTMIN + 0)
 #define SIGKVMPAUSE		(SIGRTMIN + 1)
+#define SIGKVMADDMEM		(SIGRTMIN + 2)
+#define SIGKVMDELMEM		(SIGRTMIN + 3)
 
 struct kvm {
 	int			sys_fd;		/* For system ioctls(), i.e. /dev/kvm */
diff --git a/tools/kvm/include/kvm/virtio-balloon.h b/tools/kvm/include/kvm/virtio-balloon.h
new file mode 100644
index 0000000..eb49fd4
--- /dev/null
+++ b/tools/kvm/include/kvm/virtio-balloon.h
@@ -0,0 +1,8 @@
+#ifndef KVM__BLN_VIRTIO_H
+#define KVM__BLN_VIRTIO_H
+
+struct kvm;
+
+void virtio_bln__init(struct kvm *kvm);
+
+#endif /* KVM__BLN_VIRTIO_H */
diff --git a/tools/kvm/include/kvm/virtio-pci-dev.h b/tools/kvm/include/kvm/virtio-pci-dev.h
index ca373df..4eee831 100644
--- a/tools/kvm/include/kvm/virtio-pci-dev.h
+++ b/tools/kvm/include/kvm/virtio-pci-dev.h
@@ -12,6 +12,7 @@
 #define PCI_DEVICE_ID_VIRTIO_BLK		0x1001
 #define PCI_DEVICE_ID_VIRTIO_CONSOLE		0x1003
 #define PCI_DEVICE_ID_VIRTIO_RNG		0x1004
+#define PCI_DEVICE_ID_VIRTIO_BLN		0x1005
 #define PCI_DEVICE_ID_VIRTIO_P9			0x1009
 #define PCI_DEVICE_ID_VESA			0x2000
 
diff --git a/tools/kvm/kvm-run.c b/tools/kvm/kvm-run.c
index a4abf76..3b1d586 100644
--- a/tools/kvm/kvm-run.c
+++ b/tools/kvm/kvm-run.c
@@ -18,6 +18,7 @@
 #include <kvm/virtio-net.h>
 #include <kvm/virtio-console.h>
 #include <kvm/virtio-rng.h>
+#include <kvm/virtio-balloon.h>
 #include <kvm/disk-image.h>
 #include <kvm/util.h>
 #include <kvm/pci.h>
@@ -74,6 +75,7 @@ static bool single_step;
 static bool readonly_image[MAX_DISK_IMAGES];
 static bool vnc;
 static bool sdl;
+static bool balloon;
 extern bool ioport_debug;
 extern int  active_console;
 extern int  debug_iodelay;
@@ -145,6 +147,7 @@ static const struct option options[] = {
 	OPT_STRING('\0', "kvm-dev", &kvm_dev, "kvm-dev", "KVM device file"),
 	OPT_CALLBACK('\0', "virtio-9p", NULL, "dirname,tag_name",
 		     "Enable 9p over virtio", virtio_9p_rootdir_parser),
+	OPT_BOOLEAN('\0', "balloon", &balloon, "Enable virtio balloon"),
 	OPT_BOOLEAN('\0', "vnc", &vnc, "Enable VNC framebuffer"),
 	OPT_BOOLEAN('\0', "sdl", &sdl, "Enable SDL framebuffer"),
 
@@ -629,6 +632,9 @@ int kvm_cmd_run(int argc, const char **argv, const char *prefix)
 		while (virtio_rng--)
 			virtio_rng__init(kvm);
 
+	if (balloon)
+		virtio_bln__init(kvm);
+
 	if (!network)
 		network = DEFAULT_NETWORK;
 
diff --git a/tools/kvm/virtio/balloon.c b/tools/kvm/virtio/balloon.c
new file mode 100644
index 0000000..ab9ccb7
--- /dev/null
+++ b/tools/kvm/virtio/balloon.c
@@ -0,0 +1,265 @@
+#include "kvm/virtio-balloon.h"
+
+#include "kvm/virtio-pci-dev.h"
+
+#include "kvm/disk-image.h"
+#include "kvm/virtio.h"
+#include "kvm/ioport.h"
+#include "kvm/util.h"
+#include "kvm/kvm.h"
+#include "kvm/pci.h"
+#include "kvm/threadpool.h"
+#include "kvm/irq.h"
+#include "kvm/ioeventfd.h"
+
+#include <linux/virtio_ring.h>
+#include <linux/virtio_balloon.h>
+
+#include <linux/list.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <pthread.h>
+
+#define NUM_VIRT_QUEUES		2
+#define VIRTIO_BLN_QUEUE_SIZE	128
+#define VIRTIO_BLN_INFLATE	0
+#define VIRTIO_BLN_DEFLATE	1
+
+struct bln_dev {
+	struct pci_device_header pci_hdr;
+	struct list_head	list;
+
+	u16			base_addr;
+	u8			status;
+	u8			isr;
+	u16			config_vector;
+	u32			host_features;
+
+	/* virtio queue */
+	u16			queue_selector;
+	struct virt_queue	vqs[NUM_VIRT_QUEUES];
+	void			*jobs[NUM_VIRT_QUEUES];
+
+	struct virtio_balloon_config config;
+};
+
+static struct bln_dev bdev;
+extern struct kvm *kvm;
+
+static bool virtio_bln_dev_in(void *data, unsigned long offset, int size, u32 count)
+{
+	u8 *config_space = (u8 *) &bdev.config;
+
+	if (size != 1 || count != 1)
+		return false;
+
+	ioport__write8(data, config_space[offset - VIRTIO_MSI_CONFIG_VECTOR]);
+
+	return true;
+}
+
+static bool virtio_bln_dev_out(void *data, unsigned long offset, int size, u32 count)
+{
+	u8 *config_space = (u8 *) &bdev.config;
+
+	if (size != 1 || count != 1)
+		return false;
+
+	config_space[offset - VIRTIO_MSI_CONFIG_VECTOR] = *(u8 *)data;
+
+	return true;
+}
+
+static bool virtio_bln_pci_io_in(struct ioport *ioport, struct kvm *kvm, u16 port, void *data, int size, u32 count)
+{
+	unsigned long offset;
+	bool ret = true;
+
+	offset = port - bdev.base_addr;
+
+	switch (offset) {
+	case VIRTIO_PCI_HOST_FEATURES:
+		ioport__write32(data, bdev.host_features);
+		break;
+	case VIRTIO_PCI_GUEST_FEATURES:
+	case VIRTIO_PCI_QUEUE_SEL:
+	case VIRTIO_PCI_QUEUE_NOTIFY:
+		ret		= false;
+		break;
+	case VIRTIO_PCI_QUEUE_PFN:
+		ioport__write32(data, bdev.vqs[bdev.queue_selector].pfn);
+		break;
+	case VIRTIO_PCI_QUEUE_NUM:
+		ioport__write16(data, VIRTIO_BLN_QUEUE_SIZE);
+		break;
+	case VIRTIO_PCI_STATUS:
+		ioport__write8(data, bdev.status);
+		break;
+	case VIRTIO_PCI_ISR:
+		ioport__write8(data, bdev.isr);
+		kvm__irq_line(kvm, bdev.pci_hdr.irq_line, VIRTIO_IRQ_LOW);
+		bdev.isr = VIRTIO_IRQ_LOW;
+		break;
+	default:
+		ret = virtio_bln_dev_in(data, offset, size, count);
+		break;
+	};
+
+	return ret;
+}
+
+static bool virtio_bln_do_io_request(struct kvm *kvm, struct bln_dev *bdev, struct virt_queue *queue)
+{
+	struct iovec iov[VIRTIO_BLN_QUEUE_SIZE];
+	unsigned int len = 0;
+	u16 out, in, head;
+	u32 *ptrs, i;
+
+	head		= virt_queue__get_iov(queue, iov, &out, &in, kvm);
+	ptrs		= iov[0].iov_base;
+	len		= iov[0].iov_len / sizeof(u32);
+
+	for (i = 0 ; i < len ; i++) {
+		void *guest_ptr;
+
+		guest_ptr = guest_flat_to_host(kvm, ptrs[i] << VIRTIO_BALLOON_PFN_SHIFT);
+		if (queue == &bdev->vqs[VIRTIO_BLN_INFLATE]) {
+			madvise(guest_ptr, 1 << VIRTIO_BALLOON_PFN_SHIFT, MADV_DONTNEED);
+			bdev->config.actual++;
+		} else {
+			bdev->config.actual--;
+		}
+	}
+
+	virt_queue__set_used_elem(queue, head, len);
+
+	return true;
+}
+
+static void virtio_bln_do_io(struct kvm *kvm, void *param)
+{
+	struct virt_queue *vq = param;
+
+	while (virt_queue__available(vq)) {
+		virtio_bln_do_io_request(kvm, &bdev, vq);
+		virt_queue__trigger_irq(vq, bdev.pci_hdr.irq_line, &bdev.isr, kvm);
+	}
+}
+
+static void ioevent_callback(struct kvm *kvm, void *param)
+{
+	thread_pool__do_job(param);
+}
+
+static bool virtio_bln_pci_io_out(struct ioport *ioport, struct kvm *kvm, u16 port, void *data, int size, u32 count)
+{
+	unsigned long offset;
+	bool ret = true;
+	struct ioevent ioevent;
+
+	offset = port - bdev.base_addr;
+
+	switch (offset) {
+	case VIRTIO_MSI_QUEUE_VECTOR:
+	case VIRTIO_PCI_GUEST_FEATURES:
+		break;
+	case VIRTIO_PCI_QUEUE_PFN: {
+		struct virt_queue *queue;
+		void *p;
+
+		queue			= &bdev.vqs[bdev.queue_selector];
+		queue->pfn		= ioport__read32(data);
+		p			= guest_pfn_to_host(kvm, queue->pfn);
+
+		vring_init(&queue->vring, VIRTIO_BLN_QUEUE_SIZE, p, VIRTIO_PCI_VRING_ALIGN);
+
+		bdev.jobs[bdev.queue_selector] = thread_pool__add_job(kvm, virtio_bln_do_io, queue);
+
+		ioevent = (struct ioevent) {
+			.io_addr		= bdev.base_addr + VIRTIO_PCI_QUEUE_NOTIFY,
+			.io_len			= sizeof(u16),
+			.fn			= ioevent_callback,
+			.fn_ptr			= bdev.jobs[bdev.queue_selector],
+			.datamatch		= bdev.queue_selector,
+			.fn_kvm			= kvm,
+			.fd			= eventfd(0, 0),
+		};
+
+		ioeventfd__add_event(&ioevent);
+
+		break;
+	}
+	case VIRTIO_PCI_QUEUE_SEL:
+		bdev.queue_selector	= ioport__read16(data);
+		break;
+	case VIRTIO_PCI_QUEUE_NOTIFY: {
+		u16 queue_index;
+		queue_index		= ioport__read16(data);
+		thread_pool__do_job(bdev.jobs[queue_index]);
+		break;
+	}
+	case VIRTIO_PCI_STATUS:
+		bdev.status		= ioport__read8(data);
+		break;
+	case VIRTIO_MSI_CONFIG_VECTOR:
+		bdev.config_vector	= VIRTIO_MSI_NO_VECTOR;
+		break;
+	default:
+		ret = virtio_bln_dev_out(data, offset, size, count);
+		break;
+	};
+
+	return ret;
+}
+
+static struct ioport_operations virtio_bln_io_ops = {
+	.io_in				= virtio_bln_pci_io_in,
+	.io_out				= virtio_bln_pci_io_out,
+};
+
+static void handle_sigmem(int sig)
+{
+	if (sig == SIGKVMADDMEM)
+		bdev.config.num_pages += 256;
+	else
+		bdev.config.num_pages -= 256;
+
+	/* Notify that the configuration space has changed */
+	bdev.isr = VIRTIO_PCI_ISR_CONFIG;
+	kvm__irq_line(kvm, bdev.pci_hdr.irq_line, 1);
+}
+
+void virtio_bln__init(struct kvm *kvm)
+{
+	u8 pin, line, dev;
+	u16 bdev_base_addr;
+
+	signal(SIGKVMADDMEM, handle_sigmem);
+	signal(SIGKVMDELMEM, handle_sigmem);
+
+	bdev_base_addr = ioport__register(IOPORT_EMPTY, &virtio_bln_io_ops, IOPORT_SIZE, &bdev);
+
+	bdev.pci_hdr = (struct pci_device_header) {
+		.vendor_id		= PCI_VENDOR_ID_REDHAT_QUMRANET,
+		.device_id		= PCI_DEVICE_ID_VIRTIO_BLN,
+		.header_type		= PCI_HEADER_TYPE_NORMAL,
+		.revision_id		= 0,
+		.class			= 0x010000,
+		.subsys_vendor_id	= PCI_SUBSYSTEM_VENDOR_ID_REDHAT_QUMRANET,
+		.subsys_id		= VIRTIO_ID_BALLOON,
+		.bar[0]			= bdev_base_addr | PCI_BASE_ADDRESS_SPACE_IO,
+	};
+
+	bdev.base_addr = bdev_base_addr;
+
+	if (irq__register_device(VIRTIO_ID_RNG, &dev, &pin, &line) < 0)
+		return;
+
+	bdev.pci_hdr.irq_pin	= pin;
+	bdev.pci_hdr.irq_line	= line;
+	bdev.host_features	= 0;
+	memset(&bdev.config, 0, sizeof(struct virtio_balloon_config));
+
+	pci__register(&bdev.pci_hdr, dev);
+}
-- 
1.7.6