Clarification regarding "nvme discover" and setting IOSQES/IOCQES

[Sagi Grimberg]

> Hi Sagi,
> 
> Yes. The Discovery Controller currently allows it. The problem, however, 
> is that the DC seems to be expecting these values to be non-zero.
> 
> I tried setting IOCQES=0 and IOSQES=0, which the DC allows (i.e. Prop 
> Set return status=0). However, when I follow this by a "Property Get - 
> Controller Status", the Status now shows "Controller Fatal Status (CFS)" 
> (see Base specs - Figure 79).

Yes, the oversight extends to the target that expects it (shared code
with I/O controllers).

Does this fix your issue?
--
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 546a10407385..a7578c601727 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2443,6 +2443,11 @@ int nvme_disable_ctrl(struct nvme_ctrl *ctrl)
  }
  EXPORT_SYMBOL_GPL(nvme_disable_ctrl);

+static inline bool nvme_discovery_ctrl(struct nvme_ctrl *ctrl)
+{
+       return ctrl->opts && ctrl->opts->discovery_nqn;
+}
+
  int nvme_enable_ctrl(struct nvme_ctrl *ctrl)
  {
         unsigned dev_page_min;
@@ -2468,7 +2473,8 @@ int nvme_enable_ctrl(struct nvme_ctrl *ctrl)
                 ctrl->ctrl_config = NVME_CC_CSS_NVM;
         ctrl->ctrl_config |= (NVME_CTRL_PAGE_SHIFT - 12) << 
NVME_CC_MPS_SHIFT;
         ctrl->ctrl_config |= NVME_CC_AMS_RR | NVME_CC_SHN_NONE;
-       ctrl->ctrl_config |= NVME_CC_IOSQES | NVME_CC_IOCQES;
+       if (!nvme_discovery_ctrl(ctrl))
+               ctrl->ctrl_config |= NVME_CC_IOSQES | NVME_CC_IOCQES;
         ctrl->ctrl_config |= NVME_CC_ENABLE;

         ret = ctrl->ops->reg_write32(ctrl, NVME_REG_CC, ctrl->ctrl_config);
@@ -2888,11 +2894,6 @@ static const struct attribute_group 
*nvme_subsys_attrs_groups[] = {
         NULL,
  };

-static inline bool nvme_discovery_ctrl(struct nvme_ctrl *ctrl)
-{
-       return ctrl->opts && ctrl->opts->discovery_nqn;
-}
-
  static bool nvme_validate_cntlid(struct nvme_subsystem *subsys,
                 struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
  {
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 8ce4d59cc9e7..baa26a65d83d 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1107,9 +1107,14 @@ static void nvmet_start_ctrl(struct nvmet_ctrl *ctrl)
  {
         lockdep_assert_held(&ctrl->lock);

-       if (nvmet_cc_iosqes(ctrl->cc) != NVME_NVM_IOSQES ||
-           nvmet_cc_iocqes(ctrl->cc) != NVME_NVM_IOCQES ||
-           nvmet_cc_mps(ctrl->cc) != 0 ||
+       if (!ctrl->subsys->type == NVME_NQN_DISC &&
+           (nvmet_cc_iosqes(ctrl->cc) != NVME_NVM_IOSQES ||
+            nvmet_cc_iocqes(ctrl->cc) != NVME_NVM_IOCQES)) {
+               ctrl->csts = NVME_CSTS_CFS;
+               return;
+       }
+
+       if (nvmet_cc_mps(ctrl->cc) != 0 ||
             nvmet_cc_ams(ctrl->cc) != 0 ||
             nvmet_cc_css(ctrl->cc) != 0) {
                 ctrl->csts = NVME_CSTS_CFS;
--