[Bug 2166737] Re: Fix ASPM quirks execution timing by caching link states and adding pcie_aspm_remove_cap

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2166737 Title: Fix ASPM quirks execution timing by caching link states and adding pcie_aspm_remove_cap Status in linux package in Ubuntu: New Status in linux source package in Noble: In Progress Bug description: [Impact] In Launchpad bug #2132119, commit cc727f2d9a93 ("PCI/ASPM: Avoid L0s for Realtek RTS525A") was cherry-picked to 6.8 kernel to stop an AER Correctable Replay Timer Timeout storm on HP systems with Realtek RTS525A (10ec:525a). However, that fix registered quirk_disable_aspm_l0s as a DECLARE_PCI_FIXUP_HEADER quirk, while in the 6.8 kernel quirk_disable_aspm_l0s() still used the old pci_disable_link_state(), designed for DECLARE_PCI_FIXUP_FINAL. Because pci_disable_link_state() depends on link state structures that are not yet initialized during the early HEADER fixup phase, the quirk cannot function as intended. To make the RTS525A fix and other ASPM quirks work before ASPM initialization, the kernel needs the upstream infrastructure that caches advertised link states and uses pcie_aspm_remove_cap() during the HEADER fixup phase. Without these prerequisites, systems with the RTS525A card reader still hit the AER storm and freeze during shutdown or reboot: pcieport 0000:00:1c.0: AER: Correctable error message received from 0000:58:00.0 rtsx_pci 0000:58:00.0: PCIe Bus Error: severity=Correctable, type=Data Link Layer, (Transmitter ID) rtsx_pci 0000:58:00.0: device [10ec:525a] error status/mask=00001000/00006000 rtsx_pci 0000:58:00.0: [12] Timeout [Fix] Backport the 3 upstream prerequisite commits from v6.18: 1. 4495bffd86ba0 ("PCI/ASPM: Cache L0s/L1 Supported so advertised link states can be overridden") Cache the L0s Supported and L1 Supported bits early in device enumeration so HEADER quirks can override them before pcie_aspm_cap_init() runs. 2. 575b98e39d817 ("PCI/ASPM: Add pcie_aspm_remove_cap() to override advertised link states") Introduce pcie_aspm_remove_cap() to allow quirks to clear advertised ASPM L0s or L1 capabilities. 3. 30579eebba6ae ("PCI/ASPM: Convert quirks to override advertised link states") Convert existing ASPM quirks (including quirk_disable_aspm_l0s) to call pcie_aspm_remove_cap() and run as HEADER quirks so ASPM is never enabled on defective hardware. [Test Plan] On affected HP hardware with Realtek RTS525A (10ec:525a): 1. Check dmesg for AER storm: $ sudo dmesg | grep -i "AER\|rtsx_pci" Without patches: The kernel AER handler gets flooded with Replay Timer Timeout errors from 10ec:525a. With patches: No AER timeout messages appear for the device. 2. Verify reboot and shutdown: $ sudo reboot $ sudo poweroff Without patches: System freezes at shutdown/reboot screen; power LED stays on. With patches: Shutdown and reboot complete cleanly. [Where problems could occur] Could affect PCIe device enumeration and ASPM power saving states across all PCIe devices. These commits change the ASPM capability initialization flow and convert existing quirks for Intel NICs and ASMedia bridges from FINAL quirks to HEADER quirks. If pcie_aspm_remove_cap() or link state caching has a flaw, supported ASPM states on PCIe devices could be incorrectly cleared or retained. If ASPM is accidentally disabled on non-target devices, system idle power consumption on battery would increase. If disabled states fail to clear, affected devices could experience bus errors or link dropouts. [Other Info] Follow-up to LP: #2132119. All 3 prerequisite commits are upstream in v6.18. This SRU targets noble (linux 6.8). To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2166737/+subscriptions