pc: implement pc-dimm device abstraction

Each hotplug-able memory slot is a PCDIMMDevice.
A hot-add operation for a memory device:
- creates a new PCDIMMDevice and makes hotplug controller to map it into
  guest address space

Hotplug operations are done through normal device_add commands.
For migration case, all hotplugged memory devices on source should be
specified on target's command line using '-device' option with
properties set to the same values as on source.

To simplify review, patch introduces only PCDIMMDevice QOM skeleton that
will be extended by following patches to implement actual memory hotplug
and related functions.

Signed-off-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

default-configs/i386-softmmu.mak

@@ -44,3 +44,4 @@ CONFIG_APIC=y
 CONFIG_IOAPIC=y
 CONFIG_ICC_BUS=y
 CONFIG_PVPANIC=y
+CONFIG_MEM_HOTPLUG=y

default-configs/x86_64-softmmu.mak

@@ -44,3 +44,4 @@ CONFIG_APIC=y
 CONFIG_IOAPIC=y
 CONFIG_ICC_BUS=y
 CONFIG_PVPANIC=y
+CONFIG_MEM_HOTPLUG=y

hw/Makefile.objs

@@ -29,6 +29,7 @@ devices-dirs-$(CONFIG_SOFTMMU) += usb/
 devices-dirs-$(CONFIG_VIRTIO) += virtio/
 devices-dirs-$(CONFIG_SOFTMMU) += watchdog/
 devices-dirs-$(CONFIG_SOFTMMU) += xen/
+devices-dirs-$(CONFIG_MEM_HOTPLUG) += mem/
 devices-dirs-y += core/
 common-obj-y += $(devices-dirs-y)
 obj-y += $(devices-dirs-y)

hw/mem/Makefile.objs

@@ -0,0 +1 @@
+common-obj-$(CONFIG_MEM_HOTPLUG) += pc-dimm.o

hw/mem/pc-dimm.c

@@ -0,0 +1,99 @@
+/*
+ * Dimm device for Memory Hotplug
+ *
+ * Copyright ProfitBricks GmbH 2012
+ * Copyright (C) 2014 Red Hat Inc
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
+ */
+
+#include "hw/mem/pc-dimm.h"
+#include "qemu/config-file.h"
+#include "qapi/visitor.h"
+
+static Property pc_dimm_properties[] = {
+    DEFINE_PROP_UINT64(PC_DIMM_ADDR_PROP, PCDIMMDevice, addr, 0),
+    DEFINE_PROP_UINT32(PC_DIMM_NODE_PROP, PCDIMMDevice, node, 0),
+    DEFINE_PROP_INT32(PC_DIMM_SLOT_PROP, PCDIMMDevice, slot,
+                      PC_DIMM_UNASSIGNED_SLOT),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void pc_dimm_get_size(Object *obj, Visitor *v, void *opaque,
+                          const char *name, Error **errp)
+{
+    int64_t value;
+    MemoryRegion *mr;
+    PCDIMMDevice *dimm = PC_DIMM(obj);
+
+    mr = host_memory_backend_get_memory(dimm->hostmem, errp);
+    value = memory_region_size(mr);
+
+    visit_type_int(v, &value, name, errp);
+}
+
+static void pc_dimm_init(Object *obj)
+{
+    PCDIMMDevice *dimm = PC_DIMM(obj);
+
+    object_property_add(obj, PC_DIMM_SIZE_PROP, "int", pc_dimm_get_size,
+                        NULL, NULL, NULL, &error_abort);
+    object_property_add_link(obj, PC_DIMM_MEMDEV_PROP, TYPE_MEMORY_BACKEND,
+                             (Object **)&dimm->hostmem,
+                             qdev_prop_allow_set_link_before_realize,
+                             OBJ_PROP_LINK_UNREF_ON_RELEASE,
+                             &error_abort);
+}
+
+static void pc_dimm_realize(DeviceState *dev, Error **errp)
+{
+    PCDIMMDevice *dimm = PC_DIMM(dev);
+
+    if (!dimm->hostmem) {
+        error_setg(errp, "'" PC_DIMM_MEMDEV_PROP "' property is not set");
+        return;
+    }
+}
+
+static MemoryRegion *pc_dimm_get_memory_region(PCDIMMDevice *dimm)
+{
+    return host_memory_backend_get_memory(dimm->hostmem, &error_abort);
+}
+
+static void pc_dimm_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+    PCDIMMDeviceClass *ddc = PC_DIMM_CLASS(oc);
+
+    dc->realize = pc_dimm_realize;
+    dc->props = pc_dimm_properties;
+
+    ddc->get_memory_region = pc_dimm_get_memory_region;
+}
+
+static TypeInfo pc_dimm_info = {
+    .name          = TYPE_PC_DIMM,
+    .parent        = TYPE_DEVICE,
+    .instance_size = sizeof(PCDIMMDevice),
+    .instance_init = pc_dimm_init,
+    .class_init    = pc_dimm_class_init,
+    .class_size    = sizeof(PCDIMMDeviceClass),
+};
+
+static void pc_dimm_register_types(void)
+{
+    type_register_static(&pc_dimm_info);
+}
+
+type_init(pc_dimm_register_types)

include/hw/mem/pc-dimm.h

@@ -0,0 +1,73 @@
+/*
+ * PC DIMM device
+ *
+ * Copyright ProfitBricks GmbH 2012
+ * Copyright (C) 2013-2014 Red Hat Inc
+ *
+ * Authors:
+ *  Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
+ *  Igor Mammedov <imammedo@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_PC_DIMM_H
+#define QEMU_PC_DIMM_H
+
+#include "exec/memory.h"
+#include "sysemu/hostmem.h"
+#include "hw/qdev.h"
+
+#define DEFAULT_PC_DIMMSIZE (1024*1024*1024)
+
+#define TYPE_PC_DIMM "pc-dimm"
+#define PC_DIMM(obj) \
+    OBJECT_CHECK(PCDIMMDevice, (obj), TYPE_PC_DIMM)
+#define PC_DIMM_CLASS(oc) \
+    OBJECT_CLASS_CHECK(PCDIMMDeviceClass, (oc), TYPE_PC_DIMM)
+#define PC_DIMM_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(PCDIMMDeviceClass, (obj), TYPE_PC_DIMM)
+
+#define PC_DIMM_ADDR_PROP "addr"
+#define PC_DIMM_SLOT_PROP "slot"
+#define PC_DIMM_NODE_PROP "node"
+#define PC_DIMM_SIZE_PROP "size"
+#define PC_DIMM_MEMDEV_PROP "memdev"
+
+#define PC_DIMM_UNASSIGNED_SLOT -1
+
+/**
+ * PCDIMMDevice:
+ * @addr: starting guest physical address, where @PCDIMMDevice is mapped.
+ *         Default value: 0, means that address is auto-allocated.
+ * @node: numa node to which @PCDIMMDevice is attached.
+ * @slot: slot number into which @PCDIMMDevice is plugged in.
+ *        Default value: -1, means that slot is auto-allocated.
+ * @hostmem: host memory backend providing memory for @PCDIMMDevice
+ */
+typedef struct PCDIMMDevice {
+    /* private */
+    DeviceState parent_obj;
+
+    /* public */
+    uint64_t addr;
+    uint32_t node;
+    int32_t slot;
+    HostMemoryBackend *hostmem;
+} PCDIMMDevice;
+
+/**
+ * PCDIMMDeviceClass:
+ * @get_memory_region: returns #MemoryRegion associated with @dimm
+ */
+typedef struct PCDIMMDeviceClass {
+    /* private */
+    DeviceClass parent_class;
+
+    /* public */
+    MemoryRegion *(*get_memory_region)(PCDIMMDevice *dimm);
+} PCDIMMDeviceClass;
+
+#endif