hw/block/nvme: support namespace detach

Given that now we have nvme-subsys device supported, we can manage
namespace allocated, but not attached: detached.  This patch introduced
a parameter for nvme-ns device named 'detached'.  This parameter
indicates whether the given namespace device is detached from
a entire NVMe subsystem('subsys' given case, shared namespace) or a
controller('bus' given case, private namespace).

- Allocated namespace

  1) Shared ns in the subsystem 'subsys0':

     -device nvme-ns,id=ns1,drive=blknvme0,nsid=1,subsys=subsys0,detached=true

  2) Private ns for the controller 'nvme0' of the subsystem 'subsys0':

     -device nvme-subsys,id=subsys0
     -device nvme,serial=foo,id=nvme0,subsys=subsys0
     -device nvme-ns,id=ns1,drive=blknvme0,nsid=1,bus=nvme0,detached=true

  3) (Invalid case) Controller 'nvme0' has no subsystem to manage ns:

     -device nvme,serial=foo,id=nvme0
     -device nvme-ns,id=ns1,drive=blknvme0,nsid=1,bus=nvme0,detached=true

Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>

hw/block/nvme-ns.c

@@ -399,6 +399,7 @@ static Property nvme_ns_props[] = {
     DEFINE_BLOCK_PROPERTIES(NvmeNamespace, blkconf),
     DEFINE_PROP_LINK("subsys", NvmeNamespace, subsys, TYPE_NVME_SUBSYS,
                      NvmeSubsystem *),
+    DEFINE_PROP_BOOL("detached", NvmeNamespace, params.detached, false),
     DEFINE_PROP_UINT32("nsid", NvmeNamespace, params.nsid, 0),
     DEFINE_PROP_UUID("uuid", NvmeNamespace, params.uuid),
     DEFINE_PROP_UINT16("mssrl", NvmeNamespace, params.mssrl, 128),

hw/block/nvme-ns.h

@@ -26,6 +26,7 @@ typedef struct NvmeZone {
 } NvmeZone;
 
 typedef struct NvmeNamespaceParams {
+    bool     detached;
     uint32_t nsid;
     QemuUUID uuid;
 

hw/block/nvme-subsys.h

@@ -23,6 +23,7 @@ typedef struct NvmeSubsystem {
     uint8_t     subnqn[256];
 
     NvmeCtrl    *ctrls[NVME_SUBSYS_MAX_CTRLS];
+    /* Allocated namespaces for this subsystem */
     NvmeNamespace *namespaces[NVME_SUBSYS_MAX_NAMESPACES];
 
     struct {

hw/block/nvme.c

@@ -27,7 +27,7 @@
  *              subsys=<subsys_id>
  *      -device nvme-ns,drive=<drive_id>,bus=<bus_name>,nsid=<nsid>,\
  *              zoned=<true|false[optional]>, \
- *              subsys=<subsys_id>
+ *              subsys=<subsys_id>,detached=<true|false[optional]>
  *
  * 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
@@ -91,6 +91,13 @@
  *   subsystem. Otherwise, `bus` must be given to attach this namespace to a
  *   specific controller as a non-shared namespace.
  *
+ * - `detached`
+ *   This parameter is only valid together with the `subsys` parameter. If left
+ *   at the default value (`false/off`), the namespace will be attached to all
+ *   controllers in the NVMe subsystem at boot-up. If set to `true/on`, the
+ *   namespace will be be available in the subsystem not not attached to any
+ *   controllers.
+ *
  * Setting `zoned` to true selects Zoned Command Set at the namespace.
  * In this case, the following namespace properties are available to configure
  * zoned operation:
@@ -4655,6 +4662,20 @@ static void nvme_init_state(NvmeCtrl *n)
     n->aer_reqs = g_new0(NvmeRequest *, n->params.aerl + 1);
 }
 
+static int nvme_attach_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
+{
+    if (nvme_ns_is_attached(n, ns)) {
+        error_setg(errp,
+                   "namespace %d is already attached to controller %d",
+                   nvme_nsid(ns), n->cntlid);
+        return -1;
+    }
+
+    nvme_ns_attach(n, ns);
+
+    return 0;
+}
+
 int nvme_register_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
 {
     uint32_t nsid = nvme_nsid(ns);
@@ -4686,7 +4707,23 @@ int nvme_register_namespace(NvmeCtrl *n, NvmeNamespace *ns, Error **errp)
 
     trace_pci_nvme_register_namespace(nsid);
 
-    n->namespaces[nsid - 1] = ns;
+    /*
+     * If subsys is not given, namespae is always attached to the controller
+     * because there's no subsystem to manage namespace allocation.
+     */
+    if (!n->subsys) {
+        if (ns->params.detached) {
+            error_setg(errp,
+                       "detached needs nvme-subsys specified nvme or nvme-ns");
+            return -1;
+        }
+
+        return nvme_attach_namespace(n, ns, errp);
+    } else {
+        if (!ns->params.detached) {
+            return nvme_attach_namespace(n, ns, errp);
+        }
+    }
 
     n->dmrsl = MIN_NON_ZERO(n->dmrsl,
                             BDRV_REQUEST_MAX_BYTES / nvme_l2b(ns, 1));

hw/block/nvme.h

@@ -189,6 +189,10 @@ typedef struct NvmeCtrl {
     NvmeSubsystem   *subsys;
 
     NvmeNamespace   namespace;
+    /*
+     * Attached namespaces to this controller.  If subsys is not given, all
+     * namespaces in this list will always be attached.
+     */
     NvmeNamespace   *namespaces[NVME_MAX_NAMESPACES];
     NvmeSQueue      **sq;
     NvmeCQueue      **cq;
@@ -207,6 +211,24 @@ static inline NvmeNamespace *nvme_ns(NvmeCtrl *n, uint32_t nsid)
     return n->namespaces[nsid - 1];
 }
 
+static inline bool nvme_ns_is_attached(NvmeCtrl *n, NvmeNamespace *ns)
+{
+    int nsid;
+
+    for (nsid = 1; nsid <= n->num_namespaces; nsid++) {
+        if (nvme_ns(n, nsid) == ns) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+static inline void nvme_ns_attach(NvmeCtrl *n, NvmeNamespace *ns)
+{
+    n->namespaces[nvme_nsid(ns) - 1] = ns;
+}
+
 static inline NvmeCQueue *nvme_cq(NvmeRequest *req)
 {
     NvmeSQueue *sq = req->sq;