pc-dimm: add busy address check and address auto-allocation

- if 'addr' property is not specified on -device/device_add command,
treat the default value as request for assigning PCDIMMDevice to
the first free memory region.

- if 'addr' is provided with -device/device_add command, attempt to
use it or fail command if it's already occupied or falls inside
of an existing PCDIMMDevice memory region.

Note:
GCompareFunc(a, b) used by g_slist_insert_sorted() returns 'gint',
however it might be too small to fit difference between
2 addresses. So use 128bit to calculate the difference and normalize
result to -1/0/1 return values.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Andrey Korolyov <andrey@xdel.ru>

MST: commit log tweaks

hw/i386/pc.c

@@ -1558,6 +1558,15 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
         goto out;
     }
 
+    addr = pc_dimm_get_free_addr(pcms->hotplug_memory_base,
+                                 memory_region_size(&pcms->hotplug_memory),
+                                 !addr ? NULL : &addr,
+                                 memory_region_size(mr), &local_err);
+    if (local_err) {
+        goto out;
+    }
+    object_property_set_int(OBJECT(dev), addr, PC_DIMM_ADDR_PROP, &local_err);
+
     memory_region_add_subregion(&pcms->hotplug_memory,
                                 addr - pcms->hotplug_memory_base, mr);
     vmstate_register_ram(mr, dev);

hw/mem/pc-dimm.c

@@ -21,6 +21,88 @@
 #include "hw/mem/pc-dimm.h"
 #include "qemu/config-file.h"
 #include "qapi/visitor.h"
+#include "qemu/range.h"
+
+static gint pc_dimm_addr_sort(gconstpointer a, gconstpointer b)
+{
+    PCDIMMDevice *x = PC_DIMM(a);
+    PCDIMMDevice *y = PC_DIMM(b);
+    Int128 diff = int128_sub(int128_make64(x->addr), int128_make64(y->addr));
+
+    if (int128_lt(diff, int128_zero())) {
+        return -1;
+    } else if (int128_gt(diff, int128_zero())) {
+        return 1;
+    }
+    return 0;
+}
+
+static int pc_dimm_built_list(Object *obj, void *opaque)
+{
+    GSList **list = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_PC_DIMM)) {
+        DeviceState *dev = DEVICE(obj);
+        if (dev->realized) { /* only realized DIMMs matter */
+            *list = g_slist_insert_sorted(*list, dev, pc_dimm_addr_sort);
+        }
+    }
+
+    object_child_foreach(obj, pc_dimm_built_list, opaque);
+    return 0;
+}
+
+uint64_t pc_dimm_get_free_addr(uint64_t address_space_start,
+                               uint64_t address_space_size,
+                               uint64_t *hint, uint64_t size,
+                               Error **errp)
+{
+    GSList *list = NULL, *item;
+    uint64_t new_addr, ret = 0;
+    uint64_t address_space_end = address_space_start + address_space_size;
+
+    assert(address_space_end > address_space_size);
+    object_child_foreach(qdev_get_machine(), pc_dimm_built_list, &list);
+
+    if (hint) {
+        new_addr = *hint;
+    } else {
+        new_addr = address_space_start;
+    }
+
+    /* find address range that will fit new DIMM */
+    for (item = list; item; item = g_slist_next(item)) {
+        PCDIMMDevice *dimm = item->data;
+        uint64_t dimm_size = object_property_get_int(OBJECT(dimm),
+                                                     PC_DIMM_SIZE_PROP,
+                                                     errp);
+        if (errp && *errp) {
+            goto out;
+        }
+
+        if (ranges_overlap(dimm->addr, dimm_size, new_addr, size)) {
+            if (hint) {
+                DeviceState *d = DEVICE(dimm);
+                error_setg(errp, "address range conflicts with '%s'", d->id);
+                goto out;
+            }
+            new_addr = dimm->addr + dimm_size;
+        }
+    }
+    ret = new_addr;
+
+    if (new_addr < address_space_start) {
+        error_setg(errp, "can't add memory [0x%" PRIx64 ":0x%" PRIx64
+                   "] at 0x%" PRIx64, new_addr, size, address_space_start);
+    } else if ((new_addr + size) > address_space_end) {
+        error_setg(errp, "can't add memory [0x%" PRIx64 ":0x%" PRIx64
+                   "] beyond 0x%" PRIx64, new_addr, size, address_space_end);
+    }
+
+out:
+    g_slist_free(list);
+    return ret;
+}
 
 static Property pc_dimm_properties[] = {
     DEFINE_PROP_UINT64(PC_DIMM_ADDR_PROP, PCDIMMDevice, addr, 0),

include/hw/mem/pc-dimm.h

@@ -70,4 +70,8 @@ typedef struct PCDIMMDeviceClass {
     MemoryRegion *(*get_memory_region)(PCDIMMDevice *dimm);
 } PCDIMMDeviceClass;
 
+uint64_t pc_dimm_get_free_addr(uint64_t address_space_start,
+                               uint64_t address_space_size,
+                               uint64_t *hint, uint64_t size,
+                               Error **errp);
 #endif