[Qemu-devel] [QEMU 4/7] balloon: get free page info from guest

[Liang Li <liang.z.li@intel.com>]

Add a new feature to get the free page information from guest,
the free page information is saved in a bitmap. Please note that
'free page' only means these pages are free before the request,
some of the pages will become no free during the process of
sending the free page bitmap to QEMU.

Signed-off-by: Liang Li <liang.z.li@intel.com>
---
 balloon.c                          | 24 +++++++++++-
 hw/virtio/virtio-balloon.c         | 75 +++++++++++++++++++++++++++++++++++++-
 include/hw/virtio/virtio-balloon.h |  4 ++
 include/sysemu/balloon.h           |  8 ++++
 4 files changed, 108 insertions(+), 3 deletions(-)

diff --git a/balloon.c b/balloon.c
index 3d96111..c74c472 100644
--- a/balloon.c
+++ b/balloon.c
@@ -37,6 +37,7 @@
 static QEMUBalloonEvent *balloon_event_fn;
 static QEMUBalloonStatus *balloon_stat_fn;
 static QEMUBalloonDropCache *balloon_drop_cache_fn;
+static QEMUBalloonGetFreePage *balloon_get_free_page_fn;
 static void *balloon_opaque;
 static bool balloon_inhibited;
 
@@ -68,10 +69,11 @@ static bool have_balloon(Error **errp)
 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
                              QEMUBalloonStatus *stat_func,
                              QEMUBalloonDropCache *drop_cache_func,
+                             QEMUBalloonGetFreePage *get_free_page_func,
                              void *opaque)
 {
     if (balloon_event_fn || balloon_stat_fn || balloon_drop_cache_fn
-        || balloon_opaque) {
+        || balloon_get_free_page_fn || balloon_opaque) {
         /* We're already registered one balloon handler.  How many can
          * a guest really have?
          */
@@ -80,6 +82,7 @@ int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
     balloon_event_fn = event_func;
     balloon_stat_fn = stat_func;
     balloon_drop_cache_fn = drop_cache_func;
+    balloon_get_free_page_fn = get_free_page_func;
     balloon_opaque = opaque;
     return 0;
 }
@@ -92,6 +95,7 @@ void qemu_remove_balloon_handler(void *opaque)
     balloon_event_fn = NULL;
     balloon_stat_fn = NULL;
     balloon_drop_cache_fn = NULL;
+    balloon_get_free_page_fn = NULL;
     balloon_opaque = NULL;
 }
 
@@ -141,3 +145,21 @@ void qmp_balloon_drop_cache(DropCacheType type, Error **errp)
 
     balloon_drop_cache_fn(balloon_opaque, type);
 }
+
+bool balloon_free_pages_support(void)
+{
+    return balloon_get_free_page_fn ? true : false;
+}
+
+BalloonReqStatus balloon_get_free_pages(unsigned long *bitmap, unsigned long len)
+{
+    if (!balloon_get_free_page_fn) {
+        return REQ_UNSUPPORT;
+    }
+
+    if (!bitmap) {
+        return REQ_INVALID_PARAM;
+    }
+
+    return balloon_get_free_page_fn(balloon_opaque, bitmap, len);
+}
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 4757ba5..30ba074 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -38,6 +38,7 @@
 
 enum balloon_req_id {
        BALLOON_DROP_CACHE,
+       BALLOON_GET_FREE_PAGES,
 };
 
 static void balloon_page(void *addr, int deflate)
@@ -435,7 +436,8 @@ static void virtio_balloon_handle_resp(VirtIODevice *vdev, VirtQueue *vq)
     VirtIOBalloon *s = VIRTIO_BALLOON(vdev);
     VirtQueueElement *elem;
     size_t offset = 0;
-    uint32_t tmp32, id = 0;
+    uint32_t tmp32, id = 0, page_shift;
+    uint64_t base_pfn, tmp64, bmap_len;
 
     elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
     if (!elem) {
@@ -457,6 +459,32 @@ static void virtio_balloon_handle_resp(VirtIODevice *vdev, VirtQueue *vq)
     case BALLOON_DROP_CACHE:
         s->req_status = REQ_DONE;
         break;
+    case BALLOON_GET_FREE_PAGES:
+        iov_to_buf(elem->out_sg, elem->out_num, offset,
+                   &tmp32, sizeof(uint32_t));
+        page_shift = virtio_ldl_p(vdev, &tmp32);
+        offset += sizeof(uint32_t);
+        s->page_shift = page_shift;
+
+        iov_to_buf(elem->out_sg, elem->out_num, offset,
+                   &tmp64, sizeof(uint64_t));
+        base_pfn = virtio_ldq_p(vdev, &tmp64);
+        offset += sizeof(uint64_t);
+        s->base_pfn = base_pfn;
+
+        iov_to_buf(elem->out_sg, elem->out_num, offset,
+                   &tmp64, sizeof(uint64_t));
+        bmap_len = virtio_ldq_p(vdev, &tmp64);
+        offset += sizeof(uint64_t);
+        if (s->bmap_len < bmap_len) {
+             s->req_status = REQ_INVALID_PARAM;
+             return;
+        }
+
+        iov_to_buf(elem->out_sg, elem->out_num, offset,
+                   s->free_page_bmap, bmap_len);
+        s->req_status = REQ_DONE;
+       break;
     default:
         break;
     }
@@ -574,6 +602,48 @@ static int virtio_balloon_drop_cache(void *opaque, unsigned long type)
     return REQ_DONE;
 }
 
+static BalloonReqStatus virtio_balloon_free_pages(void *opaque,
+                                                  unsigned long *bitmap,
+                                                  unsigned long bmap_len)
+{
+    VirtIOBalloon *s = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(s);
+    VirtQueueElement *elem = s->misc_vq_elem;
+    int len;
+
+    if (!balloon_misc_supported(s)) {
+        return REQ_UNSUPPORT;
+    }
+
+    if (s->req_status == REQ_INIT) {
+        s->free_page_bmap = bitmap;
+        if (elem == NULL || !elem->in_num) {
+            elem = virtqueue_pop(s->mvq, sizeof(VirtQueueElement));
+            if (!elem) {
+                return REQ_ERROR;
+            }
+            s->misc_vq_elem = elem;
+        }
+        s->misc_req.id = BALLOON_GET_FREE_PAGES;
+        s->misc_req.param = 0;
+        s->bmap_len = bmap_len;
+        len = iov_from_buf(elem->in_sg, elem->in_num, 0, &s->misc_req,
+                           sizeof(s->misc_req));
+        virtqueue_push(s->mvq, elem, len);
+        virtio_notify(vdev, s->mvq);
+        g_free(s->misc_vq_elem);
+        s->misc_vq_elem = NULL;
+        s->req_status = REQ_ON_GOING;
+        return REQ_ERROR;
+    } else if (s->req_status == REQ_ON_GOING) {
+        return REQ_ON_GOING;
+    } else if (s->req_status == REQ_DONE) {
+        s->req_status = REQ_INIT;
+    }
+
+    return REQ_DONE;
+}
+
 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
 {
     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
@@ -637,7 +707,8 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp)
 
     ret = qemu_add_balloon_handler(virtio_balloon_to_target,
                                    virtio_balloon_stat,
-                                   virtio_balloon_drop_cache, s);
+                                   virtio_balloon_drop_cache,
+                                   virtio_balloon_free_pages, s);
 
     if (ret < 0) {
         error_setg(errp, "Only one balloon device is supported");
diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h
index a21bb45..6382bcf 100644
--- a/include/hw/virtio/virtio-balloon.h
+++ b/include/hw/virtio/virtio-balloon.h
@@ -60,6 +60,10 @@ typedef struct VirtIOBalloon {
     uint32_t host_features;
     MiscReq misc_req;
     BalloonReqStatus req_status;
+    uint64_t *free_page_bmap;
+    uint64_t bmap_len;
+    uint64_t base_pfn;
+    uint32_t page_shift;
 } VirtIOBalloon;
 
 #endif
diff --git a/include/sysemu/balloon.h b/include/sysemu/balloon.h
index 0e85f2b..6c362e8 100644
--- a/include/sysemu/balloon.h
+++ b/include/sysemu/balloon.h
@@ -15,17 +15,25 @@
 #define _QEMU_BALLOON_H
 
 #include "qapi-types.h"
+#include "hw/virtio/virtio-balloon.h"
 
 typedef void (QEMUBalloonEvent)(void *opaque, ram_addr_t target);
 typedef void (QEMUBalloonStatus)(void *opaque, BalloonInfo *info);
 typedef int (QEMUBalloonDropCache)(void *opaque, unsigned long ctrl);
+typedef BalloonReqStatus (QEMUBalloonGetFreePage)(void *opaque,
+                                                  unsigned long *bitmap,
+                                                  unsigned long len);
 
 int qemu_add_balloon_handler(QEMUBalloonEvent *event_func,
                              QEMUBalloonStatus *stat_func,
                              QEMUBalloonDropCache *drop_cache_func,
+                             QEMUBalloonGetFreePage *get_free_page_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);
+BalloonReqStatus balloon_get_free_pages(unsigned long *bitmap,
+                                        unsigned long len);
 
 #endif
-- 
1.9.1