HBA adapter (HBA355i) registers as Storage Adapter (vmhba#) preventing PCI Passthrough for Nutanix on ESXi hosts

Products

• VMware vSphere ESXi
• VMware vSphere ESXi 8.0
• VMware Cloud Foundation

Issue/Introduction

After hardware maintenance or reseating an HBA355i controller on Nutanix HCI host, the ESXi hypervisor incorrectly identifies the device as a standard storage adapter ( vmhba# ) instead of a PCI Passthrough device. 
This prevents the controller VM (CVM) from claiming the HBA, leading to local storage mounting failures. 

Validation can be confirmed by the following:

• UI Error when enabling Passthrough on this device:
            " An error occurred during host configuration: Failed to apply the provided configuration..
      Failed to unbind devices: 0000:##:00.0. Configuration will be applied after reboot."

• CLI Error: 
            # esxcli hardware pci pcipassthru set -d 0000:##:00.0 -a -e=1
     Error: Unable to configure the PCI device: Failed to unbind device 0000:##:00.0

• VMkernel Logs:

  • WARNING: ScsiAdapter: 3567: Cannot unregister adapter vmhba# with paths claimed
    
    WARNING: Unregister of vmkAdapter vmhba# failed: Busy
    
    Device: 412: psa:driver->ops.detachDevice:0 ms

Environment

VMware ESXi 7.0.x
VMware ESXi 8.0.x
VMware ESXi 9.0.x
VMware ESXi (Running on Nutanix HCI)
Broadcom/LSI HBA355i Front

Cause

The native ESXi driver lsi_msgpt35 driver module is enabled and claims the HBA355i during the boot sequence.
Because the driver immediately establishes active paths to the enclosure/LUNs, the device enters a "Busy" state.
This prevents the kernel from dynamically unbinding the device to satisfy a PCI Passthrough request. 

Resolution

To allow the kernel to unbind the device, you must manually release the active paths and disable the driver module before enabling passthrough. 
Note: Host must be in maintenance mode before making these changes. Replace the # in vmhba# with the appropriate HBA device number.

1. Identify active paths: Run one of these commands below   to confirm the device is busy.

   • esxcfg-scsidevs -A  

   • esxcfg-mpath -b

   • esxcli storage core path list -A vmhba# 

2. Unclaim the device paths: Force the Pluggable Storage Architecture (PSA) to release the device:      # esxcli storage core claiming unclaim -t location -A vmhba#

3. Disable the driver module: Prevent the native driver from claiming the device on subsequent boots:  # esxcli system module set --enabled=false --module=lsi_msgpt35

4. Enable Passthrough:

   • In the vSphere Client, navigate to Host > Configure > Hardware > PCI Devices.

   • Locate the HBA355i and click Toggle Passthrough.

5. Persist and Reboot:

   • Run /sbin/auto-backup.sh to ensure configuration changes are saved to the boot bank.

   • Reboot the ESXi host.

6. Verification: After reboot, verify the module status: esxcli system module list | grep lsi_msgpt35   Ensure both 'Enabled' and 'Loaded' columns are false.

Additional Information

For Nutanix environments, the HBA must be in passthrough mode for the CVM to achieve direct I/O access to the physical drives.