Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into staging

* remotes/qmp-unstable/queue/qmp:
  docs: add memory-hotplug.txt
  qemu-options.hx: improve -m description
  virtio-balloon: Add some trace events
  virtio-balloon: Fix balloon not working correctly when hotplug memory
  pc-dimm: add a function to calculate VM's current RAM size

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 41 insertions, 6 deletions

diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index f27a087061..de81b9ceab 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -100,6 +100,32 @@ int qmp_pc_dimm_device_list(Object *obj, void *opaque)
     return 0;
 }
 
+ram_addr_t get_current_ram_size(void)
+{
+    MemoryDeviceInfoList *info_list = NULL;
+    MemoryDeviceInfoList **prev = &info_list;
+    MemoryDeviceInfoList *info;
+    ram_addr_t size = ram_size;
+
+    qmp_pc_dimm_device_list(qdev_get_machine(), &prev);
+    for (info = info_list; info; info = info->next) {
+        MemoryDeviceInfo *value = info->value;
+
+        if (value) {
+            switch (value->kind) {
+            case MEMORY_DEVICE_INFO_KIND_DIMM:
+                size += value->dimm->size;
+                break;
+            default:
+                break;
+            }
+        }
+    }
+    qapi_free_MemoryDeviceInfoList(info_list);
+
+    return size;
+}
+
 static int pc_dimm_slot2bitmap(Object *obj, void *opaque)
 {
     unsigned long *bitmap = opaque;
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 7bfbb75ad3..8a48d2a178 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -25,6 +25,7 @@
 #include "exec/address-spaces.h"
 #include "qapi/visitor.h"
 #include "qapi-event.h"
+#include "trace.h"
 
 #if defined(__linux__)
 #include <sys/mman.h>
@@ -222,6 +223,8 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
             if (!int128_nz(section.size) || !memory_region_is_ram(section.mr))
                 continue;
 
+            trace_virtio_balloon_handle_output(memory_region_name(section.mr),
+                                               pa);
             /* 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;
@@ -285,6 +288,7 @@ static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data)
     config.num_pages = cpu_to_le32(dev->num_pages);
     config.actual = cpu_to_le32(dev->actual);
 
+    trace_virtio_balloon_get_config(config.num_pages, config.actual);
     memcpy(config_data, &config, sizeof(struct virtio_balloon_config));
 }
 
@@ -294,13 +298,16 @@ static void virtio_balloon_set_config(VirtIODevice *vdev,
     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
     struct virtio_balloon_config config;
     uint32_t oldactual = dev->actual;
+    ram_addr_t vm_ram_size = get_current_ram_size();
+
     memcpy(&config, config_data, sizeof(struct virtio_balloon_config));
     dev->actual = le32_to_cpu(config.actual);
     if (dev->actual != oldactual) {
-        qapi_event_send_balloon_change(ram_size -
+        qapi_event_send_balloon_change(vm_ram_size -
                         ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT),
                         &error_abort);
     }
+    trace_virtio_balloon_set_config(dev->actual, oldactual);
 }
 
 static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
@@ -312,22 +319,24 @@ static uint32_t virtio_balloon_get_features(VirtIODevice *vdev, uint32_t f)
 static void virtio_balloon_stat(void *opaque, BalloonInfo *info)
 {
     VirtIOBalloon *dev = opaque;
-    info->actual = ram_size - ((uint64_t) dev->actual <<
-                               VIRTIO_BALLOON_PFN_SHIFT);
+    info->actual = get_current_ram_size() - ((uint64_t) dev->actual <<
+                                             VIRTIO_BALLOON_PFN_SHIFT);
 }
 
 static void virtio_balloon_to_target(void *opaque, ram_addr_t target)
 {
     VirtIOBalloon *dev = VIRTIO_BALLOON(opaque);
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    ram_addr_t vm_ram_size = get_current_ram_size();
 
-    if (target > ram_size) {
-        target = ram_size;
+    if (target > vm_ram_size) {
+        target = vm_ram_size;
     }
     if (target) {
-        dev->num_pages = (ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
+        dev->num_pages = (vm_ram_size - target) >> VIRTIO_BALLOON_PFN_SHIFT;
         virtio_notify_config(vdev);
     }
+    trace_virtio_balloon_to_target(target, dev->num_pages);
 }
 
 static void virtio_balloon_save(QEMUFile *f, void *opaque)