Extend the virtio balloon device to support a new feature, this
new feature can help to get guest's free pages information, which
can be used for live migration optimzation.
Signed-off-by: Liang Li <liang.z.li@xxxxxxxxx>
---
balloon.c | 30 ++++++++-
hw/virtio/virtio-balloon.c | 81 ++++++++++++++++++++++++-
include/hw/virtio/virtio-balloon.h | 17 +++++-
include/standard-headers/linux/virtio_balloon.h | 1 +
include/sysemu/balloon.h | 10 ++-
5 files changed, 134 insertions(+), 5 deletions(-)
diff --git a/balloon.c b/balloon.c
index f2ef50c..a37717e 100644
--- a/balloon.c
+++ b/balloon.c
@@ -36,6 +36,7 @@
static QEMUBalloonEvent *balloon_event_fn;
static QEMUBalloonStatus *balloon_stat_fn;
+static QEMUBalloonFreePages *balloon_free_pages_fn;
static void *balloon_opaque;
static bool balloon_inhibited;
@@ -65,9 +66,12 @@ static bool have_balloon(Error **errp)
}
int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
- QEMUBalloonStatus *stat_func, void *opaque)
+ QEMUBalloonStatus *stat_func,
+ QEMUBalloonFreePages *free_pages_func,
+ void *opaque)
{
- if (balloon_event_fn || balloon_stat_fn || balloon_opaque) {
+ if (balloon_event_fn || balloon_stat_fn || balloon_free_pages_fn
+ || balloon_opaque) {
/* We're already registered one balloon handler. How many can
* a guest really have?
*/
@@ -75,6 +79,7 @@ int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
}
balloon_event_fn = event_func;
balloon_stat_fn = stat_func;
+ balloon_free_pages_fn = free_pages_func;
balloon_opaque = opaque;
return 0;
}
@@ -86,6 +91,7 @@ void qemu_remove_balloon_handler(void *opaque)
}
balloon_event_fn = NULL;
balloon_stat_fn = NULL;
+ balloon_free_pages_fn = NULL;
balloon_opaque = NULL;
}
@@ -116,3 +122,23 @@ void qmp_balloon(int64_t target, Error **errp)
trace_balloon_event(balloon_opaque, target);
balloon_event_fn(balloon_opaque, target);
}
+
+bool balloon_free_pages_support(void)
+{
+ return balloon_free_pages_fn ? true : false;
+}
+
+int balloon_get_free_pages(unsigned long *free_pages_bitmap,
+ unsigned long *free_pages_count)
+{
+ if (!balloon_free_pages_fn) {
+ return -1;
+ }
+
+ if (!free_pages_bitmap || !free_pages_count) {
+ return -1;
+ }
+
+ return balloon_free_pages_fn(balloon_opaque,
+ free_pages_bitmap, free_pages_count);
+ }
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index e9c30e9..a5b9d08 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -76,6 +76,12 @@ static bool balloon_stats_supported(const VirtIOBalloon *s)
return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_STATS_VQ);
}
+static bool balloon_free_pages_supported(const VirtIOBalloon *s)
+{
+ VirtIODevice *vdev = VIRTIO_DEVICE(s);
+ return virtio_vdev_has_feature(vdev, VIRTIO_BALLOON_F_GET_FREE_PAGES);
+}
+
static bool balloon_stats_enabled(const VirtIOBalloon *s)
{
return s->stats_poll_interval > 0;
@@ -293,6 +299,37 @@ out:
}
}
+static void virtio_balloon_get_free_pages(VirtIODevice *vdev, VirtQueue *vq)
+{
+ VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
+ VirtQueueElement *elem;
+ size_t offset = 0;
+ uint64_t bitmap_bytes = 0, free_pages_count = 0;
+
+ elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
+ if (!elem) {
+ return;
+ }
+ s->free_pages_vq_elem = elem;
+
+ if (!elem->out_num) {
+ return;
+ }
+
+ iov_to_buf(elem->out_sg, elem->out_num, offset,
+ &free_pages_count, sizeof(uint64_t));
+
+ offset += sizeof(uint64_t);
+ iov_to_buf(elem->out_sg, elem->out_num, offset,
+ &bitmap_bytes, sizeof(uint64_t));
+
+ offset += sizeof(uint64_t);
+ iov_to_buf(elem->out_sg, elem->out_num, offset,
+ s->free_pages_bitmap, bitmap_bytes);
+ s->req_status = DONE;
+ s->free_pages_count = free_pages_count;
+}
+
static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
{
VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
@@ -362,6 +399,7 @@ static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
f |= dev->host_features;
virtio_add_feature(&f, VIRTIO_BALLOON_F_STATS_VQ);
+ virtio_add_feature(&f, VIRTIO_BALLOON_F_GET_FREE_PAGES);
return f;
}
@@ -372,6 +410,45 @@ static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
VIRTIO_BALLOON_PFN_SHIFT);
}
+static int virtio_balloon_free_pages(void *opaque,
+ unsigned long *free_pages_bitmap,
+ unsigned long *free_pages_count)
+{
+ VirtIOBalloon *s = opaque;
+ VirtIODevice *vdev = VIRTIO_DEVICE(s);
+ VirtQueueElement *elem = s->free_pages_vq_elem;
+ int len;
+
+ if (!balloon_free_pages_supported(s)) {
+ return -1;
+ }
+
+ if (s->req_status == NOT_STARTED) {
+ s->free_pages_bitmap = free_pages_bitmap;
+ s->req_status = STARTED;
+ s->mem_layout.low_mem = pc_get_lowmem(PC_MACHINE(current_machine));
+ if (!elem->in_num) {
+ elem = virtqueue_pop(s->fvq, sizeof(VirtQueueElement));
+ if (!elem) {
+ return 0;
+ }
+ s->free_pages_vq_elem = elem;
+ }
+ len = iov_from_buf(elem->in_sg, elem->in_num, 0, &s->mem_layout,
+ sizeof(s->mem_layout));
+ virtqueue_push(s->fvq, elem, len);
+ virtio_notify(vdev, s->fvq);
+ return 0;
+ } else if (s->req_status == STARTED) {
+ return 0;
+ } else if (s->req_status == DONE) {
+ *free_pages_count = s->free_pages_count;
+ s->req_status = NOT_STARTED;
+ }
+
+ return 1;
+}
+
static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
{
VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
@@ -429,7 +506,8 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
sizeof(struct virtio_balloon_config));
ret = qemu_add_balloon_handler(virtio_balloon_to_target,
- virtio_balloon_stat, s);
+ virtio_balloon_stat,
+ virtio_balloon_free_pages, s);
if (ret < 0) {
error_setg(errp, "Only one balloon device is supported");
@@ -440,6 +518,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
s->ivq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
s->dvq = virtio_add_queue(vdev, 128, virtio_balloon_handle_output);
s->svq = virtio_add_queue(vdev, 128, virtio_balloon_receive_stats);
+ s->fvq = virtio_add_queue(vdev, 128, virtio_balloon_get_free_pages);
reset_stats(s);
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index 35f62ac..fc173e4 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -23,6 +23,16 @@
#define VIRTIO_BALLOON(obj) \
OBJECT_CHECK(VirtIOBalloon, (obj), TYPE_VIRTIO_BALLOON)
+typedef enum virtio_req_status {
+ NOT_STARTED,
+ STARTED,
+ DONE,
+} VIRTIO_REQ_STATUS;
+
+typedef struct MemLayout {
+ uint64_t low_mem;
+} MemLayout;
+
typedef struct virtio_balloon_stat VirtIOBalloonStat;
typedef struct virtio_balloon_stat_modern {
@@ -33,16 +43,21 @@ typedef struct virtio_balloon_stat_modern {
typedef struct VirtIOBalloon {
VirtIODevice parent_obj;
- VirtQueue *ivq, *dvq, *svq;
+ VirtQueue *ivq, *dvq, *svq, *fvq;
uint32_t num_pages;
uint32_t actual;
uint64_t stats[VIRTIO_BALLOON_S_NR];
VirtQueueElement *stats_vq_elem;
+ VirtQueueElement *free_pages_vq_elem;
size_t stats_vq_offset;
QEMUTimer *stats_timer;
int64_t stats_last_update;
int64_t stats_poll_interval;
uint32_t host_features;
+ uint64_t *free_pages_bitmap;
+ uint64_t free_pages_count;
+ MemLayout mem_layout;
+ VIRTIO_REQ_STATUS req_status;
} VirtIOBalloon;
#endif
diff --git a/include/standard-headers/linux/virtio_balloon.h b/include/standard-headers/linux/virtio_balloon.h
index 2e2a6dc..95b7d0c 100644
--- a/include/standard-headers/linux/virtio_balloon.h
+++ b/include/standard-headers/linux/virtio_balloon.h
@@ -34,6 +34,7 @@
#define VIRTIO_BALLOON_F_MUST_TELL_HOST 0 /* Tell before reclaiming pages */
#define VIRTIO_BALLOON_F_STATS_VQ 1 /* Memory Stats virtqueue */
#define VIRTIO_BALLOON_F_DEFLATE_ON_OOM 2 /* Deflate balloon on OOM */
+#define VIRTIO_BALLOON_F_GET_FREE_PAGES 3 /* Get the free pages bitmap */
/* Size of a PFN in the balloon interface. */
#define VIRTIO_BALLOON_PFN_SHIFT 12
diff --git a/include/sysemu/balloon.h b/include/sysemu/balloon.h
index 3f976b4..205b272 100644
--- a/include/sysemu/balloon.h
+++ b/include/sysemu/balloon.h
@@ -18,11 +18,19 @@
typedef void (QEMUBalloonEvent)(void *opaque, ram_addr_t target);
typedef void (QEMUBalloonStatus)(void *opaque, BalloonInfo *info);
+typedef int (QEMUBalloonFreePages)(void *opaque,
+ unsigned long *free_pages_bitmap,
+ unsigned long *free_pages_count);
int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
- QEMUBalloonStatus *stat_func, void *opaque);
+ QEMUBalloonStatus *stat_func,
+ QEMUBalloonFreePages *free_pages_func,
+ void *opaque);
void qemu_remove_balloon_handler(void *opaque);
bool qemu_balloon_is_inhibited(void);
void qemu_balloon_inhibit(bool state);
+bool balloon_free_pages_support(void);
+int balloon_get_free_pages(unsigned long *free_pages_bitmap,
+ unsigned long *free_pages_count);
#endif
--
1.8.3.1
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