[RFC PATCH 3/5] hw/block/nvme: add multi-controller param for mpath

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

Added mpath.ctrl parameter to set multi-controller bit[1] in CMIC field
in Identify Controller data structure.  It will indicate that a NVM
subsystem can have two or more controllers in the subsystem.

To set up multi-controller in a NVM subsystem, user needs to give same
serial parameter to the controllers (-device), but different cntlid
parameter to each controllers (-device).

Example:

  -device nvme,ctrlid=0,serial=foo,...
  -device nvme,ctrlid=1,serial=foo,...

The example above prepares two different controllers in a NVM subsystem
with the same serial which leads to same subsystem NQN.

Signed-off-by: Minwoo Im <minwoo.im.dev@gmail.com>
---
 hw/block/nvme.c | 10 ++++++++++
 hw/block/nvme.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 132e61c0ee7b..50b349cf9ea3 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -57,6 +57,11 @@
  *   This value will be reported through Identify Controller data structure
  *   with a field named CNTLID[79:78].
  *
+ * - `mpath.ctrl`
+ *   Multi-path I/O with multi-controller (default: false). A NVM subsystem
+ *   can hold two or more controllers.  This will be reflected to Identify
+ *   Controller data structure CMIC[76] field.
+ *
  * - `zoned.append_size_limit`
  *   The maximum I/O size in bytes that is allowed in Zone Append command.
  *   The default is 128KiB. Since internally this this value is maintained as
@@ -4284,6 +4289,10 @@ static void nvme_init_ctrl(NvmeCtrl *n, PCIDevice *pci_dev)
     n->bar.intmc = n->bar.intms = 0;
 
     id->cntlid = n->params.cntlid;
+
+    if (n->params.mpath_ctrl) {
+        id->cmic |= NVME_CMIC_MULTI_CTRL;
+    }
 }
 
 static void nvme_realize(PCIDevice *pci_dev, Error **errp)
@@ -4364,6 +4373,7 @@ static Property nvme_props[] = {
     DEFINE_PROP_UINT32("aer_max_queued", NvmeCtrl, params.aer_max_queued, 64),
     DEFINE_PROP_UINT8("mdts", NvmeCtrl, params.mdts, 7),
     DEFINE_PROP_BOOL("use-intel-id", NvmeCtrl, params.use_intel_id, false),
+    DEFINE_PROP_BOOL("mpath.ctrl", NvmeCtrl, params.mpath_ctrl, false),
     DEFINE_PROP_SIZE32("zoned.append_size_limit", NvmeCtrl, params.zasl_bs,
                        NVME_DEFAULT_MAX_ZA_SIZE),
     DEFINE_PROP_END_OF_LIST(),
diff --git a/hw/block/nvme.h b/hw/block/nvme.h
index 6aa9e89ac5a8..73c9c2cff247 100644
--- a/hw/block/nvme.h
+++ b/hw/block/nvme.h
@@ -21,6 +21,7 @@ typedef struct NvmeParams {
     uint8_t  mdts;
     bool     use_intel_id;
     uint32_t zasl_bs;
+    bool     mpath_ctrl;
 } NvmeParams;
 
 typedef struct NvmeAsyncEvent {
-- 
2.17.1