PCI: endpoint/NTB: Harden vNTB resource management

From:		Koichiro Den <den-AT-valinux.co.jp>
To:		ntb-AT-lists.linux.dev, linux-pci-AT-vger.kernel.org, linux-kernel-AT-vger.kernel.org
Subject:		[PATCH 0/6] PCI: endpoint/NTB: Harden vNTB resource management
Date:		Thu, 23 Oct 2025 16:17:51 +0900
Message-ID:		<20251023071757.901181-1-den@valinux.co.jp>
Cc:		jdmason-AT-kudzu.us, dave.jiang-AT-intel.com, allenbh-AT-gmail.com, mani-AT-kernel.org, kwilczynski-AT-kernel.org, kishon-AT-kernel.org, bhelgaas-AT-google.com, jbrunet-AT-baylibre.com, Frank.Li-AT-nxp.com, lpieralisi-AT-kernel.org, yebin10-AT-huawei.com, geert+renesas-AT-glider.be, arnd-AT-arndb.de
Archive-link:		Article

The vNTB endpoint function (pci-epf-vntb) can be configured and reconfigured
through configfs (link/unlink functions, start/stop the controller, update
parameters). In practice, several pitfalls present: double-unmapping when two
windows share a BAR, wrong parameter order in .drop_link leading to wrong
object lookups, duplicate EPC teardown that leads to oopses, a work item
running after resources were torn down, and inability to re-link/restart
fundamentally because ntb_dev was embedded and the vPCI bus teardown was
incomplete.

This series addresses those issues and hardens resource management across NTB
EPF and PCI EP core:

- Avoid double iounmap when PEER_SPAD and CONFIG share the same BAR.
- Fix configfs .drop_link parameter order so the correct groups are used during
  unlink.
- Remove duplicate EPC resource teardown in both pci-epf-vntb and pci-epf-ntb,
  avoiding crashes on .allow_link failures and during .drop_link.
- Stop the delayed cmd_handler work before clearing BARs/doorbells.
- Manage ntb_dev as a devm-managed allocation and implement .remove() in the
  vNTB PCI driver. Switch to pci_scan_root_bus().

With these changes, the controller can now be stopped, a function unlinked,
configfs settings updated, and the controller re-linked and restarted
without rebooting the endpoint, as long as the underlying pci_epc_ops
.stop() is non-destructive and .start() restores normal operation.

Patches 1-5 carry Fixes tags and are candidates for stable. Patch 6 is a
behavioral improvement that completes lifetime management for relink/restart
scenarios.


Koichiro Den (6):
  NTB: epf: Avoid pci_iounmap() with offset when PEER_SPAD and CONFIG
    share BAR
  PCI: endpoint: Fix parameter order for .drop_link
  PCI: endpoint: pci-epf-vntb: Remove duplicate resource teardown
  PCI: endpoint: pci-epf-ntb: Remove duplicate resource teardown
  NTB: epf: vntb: Stop cmd_andler work in epf_ntb_epc_cleanup
  PCI: endpoint: pci-epf-vntb: Manage ntb_dev lifetime and fix vpci bus
    teardown

 drivers/ntb/hw/epf/ntb_hw_epf.c               |  3 +-
 drivers/pci/endpoint/functions/pci-epf-ntb.c  | 56 +-----------
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 86 ++++++++++++-------
 drivers/pci/endpoint/pci-ep-cfs.c             |  8 +-
 4 files changed, 62 insertions(+), 91 deletions(-)

-- 
2.48.1