PCI Express Capability RMW accessors don't properly protect against concurrent access. Link Control Register is written by a number of things in the kernel in a RMW fashion without any concurrency control. This could in the unlucky case lead to losing one of the updates. One of the most obvious path which can race with most of the other LNKCTL RMW operations seems to be ASPM policy sysfs write which triggers LNKCTL update. Similarly, Root Control Register can be concurrently accessed by AER and PME. Make pcie_capability_clear_and_set_word() (and other RMW accessors that call it) to use a per device spinlock to protect the RMW operations to the Capability Registers that require locking. Convert open-coded LNKCTL RMW operations to use pcie_capability_clear_and_set_word() to benefit from the locking. There's also a related series which improves ASPM service driver and device driver coordination by removing out-of-band ASPM state management from device drivers (which will remove some of the code fragments changed by this series but it has higher regression potential which is why it seems prudent to do these changes in two steps): https://lore.kernel.org/linux-pci/20230602114751.19671-1-ilpo.jarvinen@xxxxxxxxxxxxxxx/T/#t v3: - Split link retraining change off from ASPM patch & reorder it earlier - Adjust changelog to take into account the move of link retraining code into PCI core and no longer refer to ASPM (currently in pci/enumeration branch) - based on top of pci/main v2: - Keep the RMW ops caller API the same - Make pcie_capability_clear_and_set_word() a wrapper that uses locked/unlocked variant based on the capability reg - Extracted LNKCTL2 changes out from this series to keep this purely a series which fixes something (LNKCTL2 RMW lock is necessary only when PCIe BW control is introduced). - Added Fixes tags (it's a bit rathole but yeah, they're there now). - Renamed cap_lock to pcie_cap_lock - Changed ath1* to clear the ASPMC field before setting it Ilpo Järvinen (10): PCI: Add locking to RMW PCI Express Capability Register accessors PCI: Make link retraining use RMW accessors for changing LNKCTL PCI: pciehp: Use RMW accessors for changing LNKCTL PCI/ASPM: Use RMW accessors for changing LNKCTL drm/amdgpu: Use RMW accessors for changing LNKCTL drm/radeon: Use RMW accessors for changing LNKCTL net/mlx5: Use RMW accessors for changing LNKCTL wifi: ath11k: Use RMW accessors for changing LNKCTL wifi: ath12k: Use RMW accessors for changing LNKCTL wifi: ath10k: Use RMW accessors for changing LNKCTL drivers/gpu/drm/amd/amdgpu/cik.c | 36 +++++------------- drivers/gpu/drm/amd/amdgpu/si.c | 36 +++++------------- drivers/gpu/drm/radeon/cik.c | 36 +++++------------- drivers/gpu/drm/radeon/si.c | 37 +++++------------- .../ethernet/mellanox/mlx5/core/fw_reset.c | 9 +---- drivers/net/wireless/ath/ath10k/pci.c | 9 +++-- drivers/net/wireless/ath/ath11k/pci.c | 10 +++-- drivers/net/wireless/ath/ath12k/pci.c | 10 +++-- drivers/pci/access.c | 20 ++++++++-- drivers/pci/hotplug/pciehp_hpc.c | 12 ++---- drivers/pci/pcie/aspm.c | 38 ++++++++----------- drivers/pci/probe.c | 1 + include/linux/pci.h | 34 ++++++++++++++++- 13 files changed, 128 insertions(+), 160 deletions(-) -- 2.30.2
