diff mbox

[v7,23/35] nvdimm: implement NVDIMM device abstract

Message ID 1446455617-129562-24-git-send-email-guangrong.xiao@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Xiao Guangrong Nov. 2, 2015, 9:13 a.m. UTC 
Introduce "nvdimm" device which is based on dimm device type

128K memory region which is the minimum namespace label size
required by NVDIMM Namespace Spec locates at the end of
backend memory device is reserved for label data

We can use "-m 1G,maxmem=100G,slots=10 -object memory-backend-file,
id=mem1,size=1G,mem-path=/dev/pmem0 -device nvdimm,memdev=mem1" to
create NVDIMM device for guest

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 default-configs/i386-softmmu.mak   |   1 +
 default-configs/x86_64-softmmu.mak |   1 +
 hw/acpi/memory_hotplug.c           |   6 ++
 hw/mem/Makefile.objs               |   1 +
 hw/mem/nvdimm.c                    | 116 +++++++++++++++++++++++++++++++++++++
 include/hw/mem/nvdimm.h            |  83 ++++++++++++++++++++++++++
 6 files changed, 208 insertions(+)
 create mode 100644 hw/mem/nvdimm.c
 create mode 100644 include/hw/mem/nvdimm.h

Comments

Vladimir Sementsov-Ogievskiy Nov. 13, 2015, 4:53 p.m. UTC | #1 
On 02.11.2015 12:13, Xiao Guangrong wrote:
> Introduce "nvdimm" device which is based on dimm device type
>
> 128K memory region which is the minimum namespace label size
> required by NVDIMM Namespace Spec locates at the end of
> backend memory device is reserved for label data
>
> We can use "-m 1G,maxmem=100G,slots=10 -object memory-backend-file,
> id=mem1,size=1G,mem-path=/dev/pmem0 -device nvdimm,memdev=mem1" to
> create NVDIMM device for guest
>
> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> ---
>   default-configs/i386-softmmu.mak   |   1 +
>   default-configs/x86_64-softmmu.mak |   1 +
>   hw/acpi/memory_hotplug.c           |   6 ++
>   hw/mem/Makefile.objs               |   1 +
>   hw/mem/nvdimm.c                    | 116 +++++++++++++++++++++++++++++++++++++
>   include/hw/mem/nvdimm.h            |  83 ++++++++++++++++++++++++++
>   6 files changed, 208 insertions(+)
>   create mode 100644 hw/mem/nvdimm.c
>   create mode 100644 include/hw/mem/nvdimm.h
>
> diff --git a/default-configs/i386-softmmu.mak b/default-configs/i386-softmmu.mak
> index 3ece8bb..4e84a1c 100644
> --- a/default-configs/i386-softmmu.mak
> +++ b/default-configs/i386-softmmu.mak
> @@ -47,6 +47,7 @@ CONFIG_APIC=y
>   CONFIG_IOAPIC=y
>   CONFIG_PVPANIC=y
>   CONFIG_MEM_HOTPLUG=y
> +CONFIG_NVDIMM=y
>   CONFIG_XIO3130=y
>   CONFIG_IOH3420=y
>   CONFIG_I82801B11=y
> diff --git a/default-configs/x86_64-softmmu.mak b/default-configs/x86_64-softmmu.mak
> index 92ea7c1..e877a86 100644
> --- a/default-configs/x86_64-softmmu.mak
> +++ b/default-configs/x86_64-softmmu.mak
> @@ -47,6 +47,7 @@ CONFIG_APIC=y
>   CONFIG_IOAPIC=y
>   CONFIG_PVPANIC=y
>   CONFIG_MEM_HOTPLUG=y
> +CONFIG_NVDIMM=y
>   CONFIG_XIO3130=y
>   CONFIG_IOH3420=y
>   CONFIG_I82801B11=y
> diff --git a/hw/acpi/memory_hotplug.c b/hw/acpi/memory_hotplug.c
> index 20d3093..bb5a29f 100644
> --- a/hw/acpi/memory_hotplug.c
> +++ b/hw/acpi/memory_hotplug.c
> @@ -1,6 +1,7 @@
>   #include "hw/acpi/memory_hotplug.h"
>   #include "hw/acpi/pc-hotplug.h"
>   #include "hw/mem/dimm.h"
> +#include "hw/mem/nvdimm.h"
>   #include "hw/boards.h"
>   #include "hw/qdev-core.h"
>   #include "trace.h"
> @@ -231,6 +232,11 @@ void acpi_memory_plug_cb(ACPIREGS *ar, qemu_irq irq, MemHotplugState *mem_st,
>   {
>       MemStatus *mdev;
>   
> +    /* Currently, NVDIMM hotplug has not been supported yet. */
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
> +        return;
> +    }
> +

hmm, should not check for DIMM_GET_CLASS(dev)->hotpluggable be used here 
instead for more common case covering?

>       mdev = acpi_memory_slot_status(mem_st, dev, errp);
>       if (!mdev) {
>           return;
> diff --git a/hw/mem/Makefile.objs b/hw/mem/Makefile.objs
> index cebb4b1..12d9b72 100644
> --- a/hw/mem/Makefile.objs
> +++ b/hw/mem/Makefile.objs
> @@ -1,2 +1,3 @@
>   common-obj-$(CONFIG_DIMM) += dimm.o
>   common-obj-$(CONFIG_MEM_HOTPLUG) += pc-dimm.o
> +common-obj-$(CONFIG_NVDIMM) += nvdimm.o
> diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
> new file mode 100644
> index 0000000..c310887
> --- /dev/null
> +++ b/hw/mem/nvdimm.c
> @@ -0,0 +1,116 @@
> +/*
> + * Non-Volatile Dual In-line Memory Module Virtualization Implementation
> + *
> + * Copyright(C) 2015 Intel Corporation.
> + *
> + * Author:
> + *  Xiao Guangrong <guangrong.xiao@linux.intel.com>
> + *
> + * Currently, it only supports PMEM Virtualization.
> + *
> + * 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 "qapi/visitor.h"
> +#include "hw/mem/nvdimm.h"
> +
> +static MemoryRegion *nvdimm_get_memory_region(DIMMDevice *dimm)
> +{
> +    NVDIMMDevice *nvdimm = NVDIMM(dimm);
> +
> +    /* plug a NVDIMM device which is not properly realized? */
> +    assert(memory_region_size(&nvdimm->nvdimm_mr));
> +
> +    return &nvdimm->nvdimm_mr;
> +}
> +
> +static void nvdimm_realize(DIMMDevice *dimm, Error **errp)
> +{
> +    MemoryRegion *mr;
> +    NVDIMMDevice *nvdimm = NVDIMM(dimm);
> +    uint64_t size;
> +
> +    nvdimm->label_size = MIN_NAMESPACE_LABEL_SIZE;
> +
> +    mr = host_memory_backend_get_memory(dimm->hostmem, errp);
> +    size = memory_region_size(mr);
> +
> +    if (size <= nvdimm->label_size) {
> +        char *path = object_get_canonical_path_component(OBJECT(dimm->hostmem));
> +        error_setg(errp, "the size of memdev %s (0x%" PRIx64 ") is too small"
> +                   " to contain nvdimm namespace label (0x%" PRIx64 ")", path,
> +                   memory_region_size(mr), nvdimm->label_size);
> +        return;
> +    }
> +
> +    memory_region_init_alias(&nvdimm->nvdimm_mr, OBJECT(dimm), "nvdimm-memory",
> +                             mr, 0, size - nvdimm->label_size);
> +    nvdimm->label_data = memory_region_get_ram_ptr(mr) +
> +                         memory_region_size(&nvdimm->nvdimm_mr);
> +}
> +
> +static void nvdimm_read_label_data(NVDIMMDevice *nvdimm, void *buf,
> +                                   uint64_t size, uint64_t offset)
> +{
> +    assert((nvdimm->label_size >= size + offset) && (offset + size > offset));
> +
> +    memcpy(buf, nvdimm->label_data + offset, size);
> +}
> +
> +static void nvdimm_write_label_data(NVDIMMDevice *nvdimm, const void *buf,
> +                                    uint64_t size, uint64_t offset)
> +{
> +    MemoryRegion *mr;
> +    DIMMDevice *dimm = DIMM(nvdimm);
> +    uint64_t backend_offset;
> +
> +    assert((nvdimm->label_size >= size + offset) && (offset + size > offset));
> +
> +    memcpy(nvdimm->label_data + offset, buf, size);
> +
> +    mr = host_memory_backend_get_memory(dimm->hostmem, &error_abort);
> +    backend_offset = memory_region_size(mr) - nvdimm->label_size + offset;
> +    memory_region_set_dirty(mr, backend_offset, size);
> +}
> +
> +static void nvdimm_class_init(ObjectClass *oc, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(oc);
> +    DIMMDeviceClass *ddc = DIMM_CLASS(oc);
> +    NVDIMMClass *nvc = NVDIMM_CLASS(oc);
> +
> +    /* nvdimm hotplug has not been supported yet. */
> +    dc->hotpluggable = false;
> +
> +    ddc->realize = nvdimm_realize;
> +    ddc->get_memory_region = nvdimm_get_memory_region;
> +
> +    nvc->read_label_data = nvdimm_read_label_data;
> +    nvc->write_label_data = nvdimm_write_label_data;
> +}
> +
> +static TypeInfo nvdimm_info = {
> +    .name          = TYPE_NVDIMM,
> +    .parent        = TYPE_DIMM,
> +    .instance_size = sizeof(NVDIMMDevice),
> +    .class_init    = nvdimm_class_init,
> +    .class_size    = sizeof(NVDIMMClass),
> +};
> +
> +static void nvdimm_register_types(void)
> +{
> +    type_register_static(&nvdimm_info);
> +}
> +
> +type_init(nvdimm_register_types)
> diff --git a/include/hw/mem/nvdimm.h b/include/hw/mem/nvdimm.h
> new file mode 100644
> index 0000000..cd90957
> --- /dev/null
> +++ b/include/hw/mem/nvdimm.h
> @@ -0,0 +1,83 @@
> +/*
> + * Non-Volatile Dual In-line Memory Module Virtualization Implementation
> + *
> + * Copyright(C) 2015 Intel Corporation.
> + *
> + * Author:
> + *  Xiao Guangrong <guangrong.xiao@linux.intel.com>
> + *
> + * NVDIMM specifications and some documents can be found at:
> + * NVDIMM ACPI device and NFIT are introduced in ACPI 6:
> + *      http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf
> + * NVDIMM Namespace specification:
> + *      http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf
> + * DSM Interface Example:
> + *      http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf
> + * Driver Writer's Guide:
> + *      http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdf
> + *
> + * 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_NVDIMM_H
> +#define QEMU_NVDIMM_H
> +
> +#include "hw/mem/dimm.h"
> +
> +/*
> + * The minimum label data size is required by NVDIMM Namespace
> + * specification, please refer to chapter 2 Namespaces:
> + *   "NVDIMMs following the NVDIMM Block Mode Specification use an area
> + *    at least 128KB in size, which holds around 1000 labels."
> + */
> +#define MIN_NAMESPACE_LABEL_SIZE      (128UL << 10)
> +
> +#define TYPE_NVDIMM      "nvdimm"
> +#define NVDIMM(obj)      OBJECT_CHECK(NVDIMMDevice, (obj), TYPE_NVDIMM)
> +#define NVDIMM_CLASS(oc) OBJECT_CLASS_CHECK(NVDIMMClass, (oc), TYPE_NVDIMM)
> +#define NVDIMM_GET_CLASS(obj) OBJECT_GET_CLASS(NVDIMMClass, (obj), \
> +                                               TYPE_NVDIMM)
> +
> +struct NVDIMMDevice {
> +    /* private */
> +    DIMMDevice parent_obj;
> +
> +    /* public */
> +
> +    /*
> +     * the size of label data in NVDIMM device which is presented to
> +     * guest via __DSM "Get Namespace Label Size" command.
> +     */
> +    uint64_t label_size;
> +
> +    /*
> +     * the address of label data which is read by __DSM "Get Namespace
> +     * Label Data" command and written by __DSM "Set Namespace Label
> +     * Data" command.
> +     */
> +    void *label_data;
> +
> +    /*
> +     * it's the PMEM region in NVDIMM device, which is presented to
> +     * guest via ACPI NFIT and _FIT method if NVDIMM hotplug is supported.
> +     */
> +    MemoryRegion nvdimm_mr;
> +};
> +typedef struct NVDIMMDevice NVDIMMDevice;
> +
> +struct NVDIMMClass {
> +    /* private */
> +    DIMMDeviceClass parent_class;
> +
> +    /* public */
> +    /* read @size bytes from NVDIMM label data at @offset into @buf. */
> +    void (*read_label_data)(NVDIMMDevice *nvdimm, void *buf,
> +                            uint64_t size, uint64_t offset);
> +    /* write @size bytes from @buf to NVDIMM label data at @offset. */
> +    void (*write_label_data)(NVDIMMDevice *nvdimm, const void *buf,
> +                             uint64_t size, uint64_t offset);
> +};
> +typedef struct NVDIMMClass NVDIMMClass;
> +
> +#endif
diff mbox

Patch

diff --git a/default-configs/i386-softmmu.mak b/default-configs/i386-softmmu.mak
index 3ece8bb..4e84a1c 100644
--- a/default-configs/i386-softmmu.mak
+++ b/default-configs/i386-softmmu.mak
@@ -47,6 +47,7 @@  CONFIG_APIC=y
 CONFIG_IOAPIC=y
 CONFIG_PVPANIC=y
 CONFIG_MEM_HOTPLUG=y
+CONFIG_NVDIMM=y
 CONFIG_XIO3130=y
 CONFIG_IOH3420=y
 CONFIG_I82801B11=y
diff --git a/default-configs/x86_64-softmmu.mak b/default-configs/x86_64-softmmu.mak
index 92ea7c1..e877a86 100644
--- a/default-configs/x86_64-softmmu.mak
+++ b/default-configs/x86_64-softmmu.mak
@@ -47,6 +47,7 @@  CONFIG_APIC=y
 CONFIG_IOAPIC=y
 CONFIG_PVPANIC=y
 CONFIG_MEM_HOTPLUG=y
+CONFIG_NVDIMM=y
 CONFIG_XIO3130=y
 CONFIG_IOH3420=y
 CONFIG_I82801B11=y
diff --git a/hw/acpi/memory_hotplug.c b/hw/acpi/memory_hotplug.c
index 20d3093..bb5a29f 100644
--- a/hw/acpi/memory_hotplug.c
+++ b/hw/acpi/memory_hotplug.c
@@ -1,6 +1,7 @@ 
 #include "hw/acpi/memory_hotplug.h"
 #include "hw/acpi/pc-hotplug.h"
 #include "hw/mem/dimm.h"
+#include "hw/mem/nvdimm.h"
 #include "hw/boards.h"
 #include "hw/qdev-core.h"
 #include "trace.h"
@@ -231,6 +232,11 @@  void acpi_memory_plug_cb(ACPIREGS *ar, qemu_irq irq, MemHotplugState *mem_st,
 {
     MemStatus *mdev;
 
+    /* Currently, NVDIMM hotplug has not been supported yet. */
+    if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
+        return;
+    }
+
     mdev = acpi_memory_slot_status(mem_st, dev, errp);
     if (!mdev) {
         return;
diff --git a/hw/mem/Makefile.objs b/hw/mem/Makefile.objs
index cebb4b1..12d9b72 100644
--- a/hw/mem/Makefile.objs
+++ b/hw/mem/Makefile.objs
@@ -1,2 +1,3 @@ 
 common-obj-$(CONFIG_DIMM) += dimm.o
 common-obj-$(CONFIG_MEM_HOTPLUG) += pc-dimm.o
+common-obj-$(CONFIG_NVDIMM) += nvdimm.o
diff --git a/hw/mem/nvdimm.c b/hw/mem/nvdimm.c
new file mode 100644
index 0000000..c310887
--- /dev/null
+++ b/hw/mem/nvdimm.c
@@ -0,0 +1,116 @@ 
+/*
+ * Non-Volatile Dual In-line Memory Module Virtualization Implementation
+ *
+ * Copyright(C) 2015 Intel Corporation.
+ *
+ * Author:
+ *  Xiao Guangrong <guangrong.xiao@linux.intel.com>
+ *
+ * Currently, it only supports PMEM Virtualization.
+ *
+ * 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 "qapi/visitor.h"
+#include "hw/mem/nvdimm.h"
+
+static MemoryRegion *nvdimm_get_memory_region(DIMMDevice *dimm)
+{
+    NVDIMMDevice *nvdimm = NVDIMM(dimm);
+
+    /* plug a NVDIMM device which is not properly realized? */
+    assert(memory_region_size(&nvdimm->nvdimm_mr));
+
+    return &nvdimm->nvdimm_mr;
+}
+
+static void nvdimm_realize(DIMMDevice *dimm, Error **errp)
+{
+    MemoryRegion *mr;
+    NVDIMMDevice *nvdimm = NVDIMM(dimm);
+    uint64_t size;
+
+    nvdimm->label_size = MIN_NAMESPACE_LABEL_SIZE;
+
+    mr = host_memory_backend_get_memory(dimm->hostmem, errp);
+    size = memory_region_size(mr);
+
+    if (size <= nvdimm->label_size) {
+        char *path = object_get_canonical_path_component(OBJECT(dimm->hostmem));
+        error_setg(errp, "the size of memdev %s (0x%" PRIx64 ") is too small"
+                   " to contain nvdimm namespace label (0x%" PRIx64 ")", path,
+                   memory_region_size(mr), nvdimm->label_size);
+        return;
+    }
+
+    memory_region_init_alias(&nvdimm->nvdimm_mr, OBJECT(dimm), "nvdimm-memory",
+                             mr, 0, size - nvdimm->label_size);
+    nvdimm->label_data = memory_region_get_ram_ptr(mr) +
+                         memory_region_size(&nvdimm->nvdimm_mr);
+}
+
+static void nvdimm_read_label_data(NVDIMMDevice *nvdimm, void *buf,
+                                   uint64_t size, uint64_t offset)
+{
+    assert((nvdimm->label_size >= size + offset) && (offset + size > offset));
+
+    memcpy(buf, nvdimm->label_data + offset, size);
+}
+
+static void nvdimm_write_label_data(NVDIMMDevice *nvdimm, const void *buf,
+                                    uint64_t size, uint64_t offset)
+{
+    MemoryRegion *mr;
+    DIMMDevice *dimm = DIMM(nvdimm);
+    uint64_t backend_offset;
+
+    assert((nvdimm->label_size >= size + offset) && (offset + size > offset));
+
+    memcpy(nvdimm->label_data + offset, buf, size);
+
+    mr = host_memory_backend_get_memory(dimm->hostmem, &error_abort);
+    backend_offset = memory_region_size(mr) - nvdimm->label_size + offset;
+    memory_region_set_dirty(mr, backend_offset, size);
+}
+
+static void nvdimm_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+    DIMMDeviceClass *ddc = DIMM_CLASS(oc);
+    NVDIMMClass *nvc = NVDIMM_CLASS(oc);
+
+    /* nvdimm hotplug has not been supported yet. */
+    dc->hotpluggable = false;
+
+    ddc->realize = nvdimm_realize;
+    ddc->get_memory_region = nvdimm_get_memory_region;
+
+    nvc->read_label_data = nvdimm_read_label_data;
+    nvc->write_label_data = nvdimm_write_label_data;
+}
+
+static TypeInfo nvdimm_info = {
+    .name          = TYPE_NVDIMM,
+    .parent        = TYPE_DIMM,
+    .instance_size = sizeof(NVDIMMDevice),
+    .class_init    = nvdimm_class_init,
+    .class_size    = sizeof(NVDIMMClass),
+};
+
+static void nvdimm_register_types(void)
+{
+    type_register_static(&nvdimm_info);
+}
+
+type_init(nvdimm_register_types)
diff --git a/include/hw/mem/nvdimm.h b/include/hw/mem/nvdimm.h
new file mode 100644
index 0000000..cd90957
--- /dev/null
+++ b/include/hw/mem/nvdimm.h
@@ -0,0 +1,83 @@ 
+/*
+ * Non-Volatile Dual In-line Memory Module Virtualization Implementation
+ *
+ * Copyright(C) 2015 Intel Corporation.
+ *
+ * Author:
+ *  Xiao Guangrong <guangrong.xiao@linux.intel.com>
+ *
+ * NVDIMM specifications and some documents can be found at:
+ * NVDIMM ACPI device and NFIT are introduced in ACPI 6:
+ *      http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf
+ * NVDIMM Namespace specification:
+ *      http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf
+ * DSM Interface Example:
+ *      http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf
+ * Driver Writer's Guide:
+ *      http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdf
+ *
+ * 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_NVDIMM_H
+#define QEMU_NVDIMM_H
+
+#include "hw/mem/dimm.h"
+
+/*
+ * The minimum label data size is required by NVDIMM Namespace
+ * specification, please refer to chapter 2 Namespaces:
+ *   "NVDIMMs following the NVDIMM Block Mode Specification use an area
+ *    at least 128KB in size, which holds around 1000 labels."
+ */
+#define MIN_NAMESPACE_LABEL_SIZE      (128UL << 10)
+
+#define TYPE_NVDIMM      "nvdimm"
+#define NVDIMM(obj)      OBJECT_CHECK(NVDIMMDevice, (obj), TYPE_NVDIMM)
+#define NVDIMM_CLASS(oc) OBJECT_CLASS_CHECK(NVDIMMClass, (oc), TYPE_NVDIMM)
+#define NVDIMM_GET_CLASS(obj) OBJECT_GET_CLASS(NVDIMMClass, (obj), \
+                                               TYPE_NVDIMM)
+
+struct NVDIMMDevice {
+    /* private */
+    DIMMDevice parent_obj;
+
+    /* public */
+
+    /*
+     * the size of label data in NVDIMM device which is presented to
+     * guest via __DSM "Get Namespace Label Size" command.
+     */
+    uint64_t label_size;
+
+    /*
+     * the address of label data which is read by __DSM "Get Namespace
+     * Label Data" command and written by __DSM "Set Namespace Label
+     * Data" command.
+     */
+    void *label_data;
+
+    /*
+     * it's the PMEM region in NVDIMM device, which is presented to
+     * guest via ACPI NFIT and _FIT method if NVDIMM hotplug is supported.
+     */
+    MemoryRegion nvdimm_mr;
+};
+typedef struct NVDIMMDevice NVDIMMDevice;
+
+struct NVDIMMClass {
+    /* private */
+    DIMMDeviceClass parent_class;
+
+    /* public */
+    /* read @size bytes from NVDIMM label data at @offset into @buf. */
+    void (*read_label_data)(NVDIMMDevice *nvdimm, void *buf,
+                            uint64_t size, uint64_t offset);
+    /* write @size bytes from @buf to NVDIMM label data at @offset. */
+    void (*write_label_data)(NVDIMMDevice *nvdimm, const void *buf,
+                             uint64_t size, uint64_t offset);
+};
+typedef struct NVDIMMClass NVDIMMClass;
+
+#endif