[PATCH V6 1/6] hw/block/nvme: introduce nvme-subsys device

[Minwoo Im <minwoo.im.dev@gmail.com>]

To support multi-path in QEMU NVMe device model, We need to have NVMe
subsystem hierarchy to map controllers and namespaces to a NVMe
subsystem.

This patch introduced a simple nvme-subsys device model.  The subsystem
will be prepared with subsystem NQN with <subsys_id> provided in
nvme-subsys device:

  ex) -device nvme-subsys,id=subsys0: nqn.2019-08.org.qemu:subsys0

Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
---
 hw/block/meson.build   |  2 +-
 hw/block/nvme-subsys.c | 60 ++++++++++++++++++++++++++++++++++++++++++
 hw/block/nvme-subsys.h | 25 ++++++++++++++++++
 hw/block/nvme.c        |  3 +++
 4 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100644 hw/block/nvme-subsys.c
 create mode 100644 hw/block/nvme-subsys.h

diff --git a/hw/block/meson.build b/hw/block/meson.build
index 602ca6c8541d..83ea2d37978d 100644
--- a/hw/block/meson.build
+++ b/hw/block/meson.build
@@ -13,7 +13,7 @@ softmmu_ss.add(when: 'CONFIG_SSI_M25P80', if_true: files('m25p80.c'))
 softmmu_ss.add(when: 'CONFIG_SWIM', if_true: files('swim.c'))
 softmmu_ss.add(when: 'CONFIG_XEN', if_true: files('xen-block.c'))
 softmmu_ss.add(when: 'CONFIG_SH4', if_true: files('tc58128.c'))
-softmmu_ss.add(when: 'CONFIG_NVME_PCI', if_true: files('nvme.c', 'nvme-ns.c'))
+softmmu_ss.add(when: 'CONFIG_NVME_PCI', if_true: files('nvme.c', 'nvme-ns.c', 'nvme-subsys.c'))
 
 specific_ss.add(when: 'CONFIG_VIRTIO_BLK', if_true: files('virtio-blk.c'))
 specific_ss.add(when: 'CONFIG_VHOST_USER_BLK', if_true: files('vhost-user-blk.c'))
diff --git a/hw/block/nvme-subsys.c b/hw/block/nvme-subsys.c
new file mode 100644
index 000000000000..aa82911b951c
--- /dev/null
+++ b/hw/block/nvme-subsys.c
@@ -0,0 +1,60 @@
+/*
+ * QEMU NVM Express Subsystem: nvme-subsys
+ *
+ * Copyright (c) 2021 Minwoo Im <minwoo.im.dev@gmail.com>
+ *
+ * This code is licensed under the GNU GPL v2.  Refer COPYING.
+ */
+
+#include "qemu/units.h"
+#include "qemu/osdep.h"
+#include "qemu/uuid.h"
+#include "qemu/iov.h"
+#include "qemu/cutils.h"
+#include "qapi/error.h"
+#include "hw/qdev-properties.h"
+#include "hw/qdev-core.h"
+#include "hw/block/block.h"
+#include "block/aio.h"
+#include "block/accounting.h"
+#include "sysemu/sysemu.h"
+#include "hw/pci/pci.h"
+#include "nvme.h"
+#include "nvme-subsys.h"
+
+static void nvme_subsys_setup(NvmeSubsystem *subsys)
+{
+    snprintf((char *)subsys->subnqn, sizeof(subsys->subnqn),
+             "nqn.2019-08.org.qemu:%s", subsys->parent_obj.id);
+}
+
+static void nvme_subsys_realize(DeviceState *dev, Error **errp)
+{
+    NvmeSubsystem *subsys = NVME_SUBSYS(dev);
+
+    nvme_subsys_setup(subsys);
+}
+
+static void nvme_subsys_class_init(ObjectClass *oc, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(oc);
+
+    set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
+
+    dc->realize = nvme_subsys_realize;
+    dc->desc = "Virtual NVMe subsystem";
+}
+
+static const TypeInfo nvme_subsys_info = {
+    .name = TYPE_NVME_SUBSYS,
+    .parent = TYPE_DEVICE,
+    .class_init = nvme_subsys_class_init,
+    .instance_size = sizeof(NvmeSubsystem),
+};
+
+static void nvme_subsys_register_types(void)
+{
+    type_register_static(&nvme_subsys_info);
+}
+
+type_init(nvme_subsys_register_types)
diff --git a/hw/block/nvme-subsys.h b/hw/block/nvme-subsys.h
new file mode 100644
index 000000000000..40f06a4c7db0
--- /dev/null
+++ b/hw/block/nvme-subsys.h
@@ -0,0 +1,25 @@
+/*
+ * QEMU NVM Express Subsystem: nvme-subsys
+ *
+ * Copyright (c) 2021 Minwoo Im <minwoo.im.dev@gmail.com>
+ *
+ * This code is licensed under the GNU GPL v2.  Refer COPYING.
+ */
+
+#ifndef NVME_SUBSYS_H
+#define NVME_SUBSYS_H
+
+#define TYPE_NVME_SUBSYS "nvme-subsys"
+#define NVME_SUBSYS(obj) \
+    OBJECT_CHECK(NvmeSubsystem, (obj), TYPE_NVME_SUBSYS)
+
+#define NVME_SUBSYS_MAX_CTRLS   32
+
+typedef struct NvmeCtrl NvmeCtrl;
+typedef struct NvmeNamespace NvmeNamespace;
+typedef struct NvmeSubsystem {
+    DeviceState parent_obj;
+    uint8_t     subnqn[256];
+} NvmeSubsystem;
+
+#endif /* NVME_SUBSYS_H */
diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 21aec90637fa..aabccdf36f4b 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -25,6 +25,7 @@
  *              mdts=<N[optional]>,zoned.append_size_limit=<N[optional]> \
  *      -device nvme-ns,drive=<drive_id>,bus=<bus_name>,nsid=<nsid>,\
  *              zoned=<true|false[optional]>
+ *      -device nvme-subsys,id=<subsys_id>
  *
  * Note cmb_size_mb denotes size of CMB in MB. CMB is assumed to be at
  * offset 0 in BAR2 and supports only WDS, RDS and SQS for now. By default, the
@@ -38,6 +39,8 @@
  *
  * The PMR will use BAR 4/5 exclusively.
  *
+ * To place controller(s) and namespace(s) to a subsystem, then provide
+ * nvme-subsys device as above.
  *
  * nvme device parameters
  * ~~~~~~~~~~~~~~~~~~~~~~
-- 
2.17.1