[v2] hw/nvme: CMIC.MCTRS should be set automatically for multi-controller subsystems or by parameter

Commit Message

Alan Adamson April 10, 2025, 10:02 p.m. UTC

If there are multiple controllers in a subsystem, CMIC.MCTRS should be set to on
for all controllers. For single controller subsystems, CMIC.MCTRS will be off by
default. A new subsystem specific parameter will allow setting CMIC.MCTRS for
single controller subsystems.

New NVMe Subsystem QEMU Parameter (See NVMe Specification for details):
    <subsystem>,cmic-mctrs=BOOLEAN (default: off)

Signed-off-by: Alan Adamson <[e-mail]>
---
 hw/nvme/ctrl.c   | 15 ++++++++++++++-
 hw/nvme/nvme.h   |  2 ++
 hw/nvme/subsys.c |  1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

Patch

diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
index d6b77d4fbc9d..ce0d98b39991 100644
--- a/hw/nvme/ctrl.c
+++ b/hw/nvme/ctrl.c
@@ -8880,7 +8880,20 @@  static void nvme_init_ctrl(NvmeCtrl *n, PCIDevice *pci_dev)
     id->psd[0].enlat = cpu_to_le32(0x10);
     id->psd[0].exlat = cpu_to_le32(0x4);
 
-    id->cmic |= NVME_CMIC_MULTI_CTRL;
+    n->subsys->total_ctrls++;
+
+    /* Check if there are more than 2 controllers or cmic.mctrs is enabled */
+    if (n->subsys->params.cmic_mctrs || (n->subsys->total_ctrls > 2)) {
+        id->cmic |= NVME_CMIC_MULTI_CTRL;
+    } else if (n->subsys->total_ctrls == 2) {
+        /*
+         * When the 2nd controller on this subsys is inited, CMIC.MCTRS
+         * needs to be set. Also need to go back and set CMIC.MCTRS
+         * on the first controller.
+         */
+        id->cmic |= NVME_CMIC_MULTI_CTRL;
+        n->subsys->ctrls[0]->id_ctrl.cmic |= NVME_CMIC_MULTI_CTRL;
+    }
     ctratt |= NVME_CTRATT_ENDGRPS;
 
     id->endgidmax = cpu_to_le16(0x1);
diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
index b5c9378ea4e5..061e7046550b 100644
--- a/hw/nvme/nvme.h
+++ b/hw/nvme/nvme.h
@@ -116,7 +116,9 @@  typedef struct NvmeSubsystem {
             uint16_t nruh;
             uint32_t nrg;
         } fdp;
+        bool         cmic_mctrs;
     } params;
+    uint8_t          total_ctrls;
 } NvmeSubsystem;
 
 int nvme_subsys_register_ctrl(NvmeCtrl *n, Error **errp);
diff --git a/hw/nvme/subsys.c b/hw/nvme/subsys.c
index b617ac3892a3..9c90f12b6351 100644
--- a/hw/nvme/subsys.c
+++ b/hw/nvme/subsys.c
@@ -216,6 +216,7 @@  static const Property nvme_subsystem_props[] = {
                      NVME_DEFAULT_RU_SIZE),
     DEFINE_PROP_UINT32("fdp.nrg", NvmeSubsystem, params.fdp.nrg, 1),
     DEFINE_PROP_UINT16("fdp.nruh", NvmeSubsystem, params.fdp.nruh, 0),
+    DEFINE_PROP_BOOL("cmic.mctrs", NvmeSubsystem, params.cmic_mctrs, false),
 };
 
 static void nvme_subsys_class_init(ObjectClass *oc, void *data)