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/*

 * Virtio Balloon Device

 *

 * Copyright IBM, Corp. 2008

 * Copyright (C) 2011 Red Hat, Inc.

 * Copyright (C) 2011 Amit Shah <amit.shah@redhat.com>

 *

 * Authors:

 *  Anthony Liguori   <aliguori@us.ibm.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2.  See

 * the COPYING file in the top-level directory.

 *

 */

#include "iov.h"

#include "qemu-common.h"

#include "virtio.h"

#include "pc.h"

#include "cpu.h"

#include "balloon.h"

#include "virtio-balloon.h"

#include "kvm.h"

#include "exec-memory.h"

#if defined(__linux__)

#include <sys/mman.h>

#endif

typedef struct VirtIOBalloon

{

    VirtIODevice vdev;

    VirtQueue *ivq, *dvq, *svq;

    uint32_t num_pages;

    uint32_t actual;

    uint64_t stats[VIRTIO_BALLOON_S_NR];

    VirtQueueElement stats_vq_elem;

    size_t stats_vq_offset;

    DeviceState *qdev;

} VirtIOBalloon;

static VirtIOBalloon *to_virtio_balloon(VirtIODevice *vdev)

{

    return (VirtIOBalloon *)vdev;

}

static void balloon_page(void *addr, int deflate)

{

#if defined(__linux__)

    if (!kvm_enabled() || kvm_has_sync_mmu())

        qemu_madvise(addr, TARGET_PAGE_SIZE,

                deflate ? QEMU_MADV_WILLNEED : QEMU_MADV_DONTNEED);

#endif

}

/*

 * reset_stats - Mark all items in the stats array as unset

 *

 * This function needs to be called at device intialization and before

 * before updating to a set of newly-generated stats.  This will ensure that no

 * stale values stick around in case the guest reports a subset of the supported

 * statistics.

 */

static inline void reset_stats(VirtIOBalloon *dev)

{

    int i;

    for (i = 0; i < VIRTIO_BALLOON_S_NR; dev->stats[i++] = -1);

}

static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)

{

    VirtIOBalloon *s = to_virtio_balloon(vdev);

    VirtQueueElement elem;

    MemoryRegionSection section;

    while (virtqueue_pop(vq, &elem)) {

        size_t offset = 0;

        uint32_t pfn;

        while (iov_to_buf(elem.out_sg, elem.out_num, &pfn, offset, 4) == 4) {

            ram_addr_t pa;

            ram_addr_t addr;

            pa = (ram_addr_t)ldl_p(&pfn) << VIRTIO_BALLOON_PFN_SHIFT;

            offset += 4;

            /* FIXME: remove get_system_memory(), but how? */

            section = memory_region_find(get_system_memory(), pa, 1);

            if (!section.size || !memory_region_is_ram(section.mr))

                continue;

            /* Using memory_region_get_ram_ptr is bending the rules a bit, but

               should be OK because we only want a single page.  */

            addr = section.offset_within_region;

            balloon_page(memory_region_get_ram_ptr(section.mr) + addr,

                         !!(vq == s->dvq));

        }

        virtqueue_push(vq, &elem, offset);

        virtio_notify(vdev, vq);

    }

}

static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq)

{

    VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);

    VirtQueueElement *elem = &s->stats_vq_elem;

    VirtIOBalloonStat stat;

    size_t offset = 0;

    if (!virtqueue_pop(vq, elem)) {

        return;

    }

    /* Initialize the stats to get rid of any stale values.  This is only

     * needed to handle the case where a guest supports fewer stats than it

     * used to (ie. it has booted into an old kernel).

     */

    reset_stats(s);

    while (iov_to_buf(elem->out_sg, elem->out_num, &stat, offset, sizeof(stat))

           == sizeof(stat)) {

        uint16_t tag = tswap16(stat.tag);

        uint64_t val = tswap64(stat.val);

        offset += sizeof(stat);

        if (tag < VIRTIO_BALLOON_S_NR)

            s->stats[tag] = val;

    }

    s->stats_vq_offset = offset;

}

static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)

{

    VirtIOBalloon *dev = to_virtio_balloon(vdev);

    struct virtio_balloon_config config;

    config.num_pages = cpu_to_le32(dev->num_pages);

    config.actual = cpu_to_le32(dev->actual);

    memcpy(config_data, &config, 8);

}

static void virtio_balloon_set_config(VirtIODevice *vdev,

                                      const uint8_t *config_data)

{

    VirtIOBalloon *dev = to_virtio_balloon(vdev);

    struct virtio_balloon_config config;

    memcpy(&config, config_data, 8);

    dev->actual = le32_to_cpu(config.actual);

}

static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)

{

    f |= (1 << VIRTIO_BALLOON_F_STATS_VQ);

    return f;

}

static void virtio_balloon_stat(void *opaque, BalloonInfo *info)

{

    VirtIOBalloon *dev = opaque;

#if 0

    /* Disable guest-provided stats for now. For more details please check:

     * https://bugzilla.redhat.com/show_bug.cgi?id=623903

     *

     * If you do enable it (which is probably not going to happen as we

     * need a new command for it), remember that you also need to fill the

     * appropriate members of the BalloonInfo structure so that the stats

     * are returned to the client.

     */

    if (dev->vdev.guest_features & (1 << VIRTIO_BALLOON_F_STATS_VQ)) {

        virtqueue_push(dev->svq, &dev->stats_vq_elem, dev->stats_vq_offset);

        virtio_notify(&dev->vdev, dev->svq);

        return;

    }

#endif

    /* Stats are not supported.  Clear out any stale values that might

     * have been set by a more featureful guest kernel.

     */

    reset_stats(dev);

    info->actual = ram_size - ((uint64_t) dev->actual <<

                               VIRTIO_BALLOON_PFN_SHIFT);

}

static void virtio_balloon_to_target(void *opaque, ram_addr_t target)

{

    VirtIOBalloon *dev = opaque;

    if (target > ram_size) {

        target = ram_size;

    }

    if (target) {

        dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;

        virtio_notify_config(&dev->vdev);

    }

}

static void virtio_balloon_save(QEMUFile *f, void *opaque)

{

    VirtIOBalloon *s = opaque;

    virtio_save(&s->vdev, f);

    qemu_put_be32(f, s->num_pages);

    qemu_put_be32(f, s->actual);

}

static int virtio_balloon_load(QEMUFile *f, void *opaque, int version_id)

{

    VirtIOBalloon *s = opaque;

    if (version_id != 1)

        return -EINVAL;

    virtio_load(&s->vdev, f);

    s->num_pages = qemu_get_be32(f);

    s->actual = qemu_get_be32(f);

    return 0;

}

VirtIODevice *virtio_balloon_init(DeviceState *dev)

{

    VirtIOBalloon *s;

    int ret;

    s = (VirtIOBalloon *)virtio_common_init("virtio-balloon",

                                            VIRTIO_ID_BALLOON,

                                            8, sizeof(VirtIOBalloon));

    s->vdev.get_config = virtio_balloon_get_config;

    s->vdev.set_config = virtio_balloon_set_config;

    s->vdev.get_features = virtio_balloon_get_features;

    ret = qemu_add_balloon_handler(virtio_balloon_to_target,

                                   virtio_balloon_stat, s);

    if (ret < 0) {

        virtio_cleanup(&s->vdev);

        return NULL;

    }

    s->ivq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);

    s->dvq = virtio_add_queue(&s->vdev, 128, virtio_balloon_handle_output);

    s->svq = virtio_add_queue(&s->vdev, 128, virtio_balloon_receive_stats);

    reset_stats(s);

    s->qdev = dev;

    register_savevm(dev, "virtio-balloon", -1, 1,

                    virtio_balloon_save, virtio_balloon_load, s);

    return &s->vdev;

}

void virtio_balloon_exit(VirtIODevice *vdev)

{

    VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev);

    qemu_remove_balloon_handler(s);

    unregister_savevm(s->qdev, "virtio-balloon", s);

    virtio_cleanup(vdev);

}