Re: [PATCH] PCI/DPC: Honor "pcie_ports=native" when enabling DPC

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] This problem wasn't introduced by this patch, but pre-existed in the codebase. Various PCI and CXL subsystems incorrectly check `host->native_*` flags directly without honoring the `pcie_ports=native` or `pcie_ports_dpc_native` command-line overrides.
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commit bed1438fd8fcfc05e1122790665a4045a06281cf
Author: Guixin Liu <kanie@linux.alibaba.com>

PCI/DPC: Honor "pcie_ports=native" when enabling DPC
    
This commit fixes an issue where the "pcie_ports=native" command-line
override was ignored when deciding whether to create a DPC service
device. This ensures both command-line overrides continue to work when
firmware retains AER control.

Cc: stable@vger.kernel.org

> diff --git a/drivers/pci/pcie/portdrv.c b/drivers/pci/pcie/portdrv.c
> index a9cbfc1d2bc75..a05ee7980fb27 100644
> --- a/drivers/pci/pcie/portdrv.c
> +++ b/drivers/pci/pcie/portdrv.c
> @@ -264,7 +264,7 @@ static int get_port_device_capability(struct pci_dev *dev)
>  	 */
>  	if (pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DPC) &&
>  	    pci_aer_available() &&
> -	    (pcie_ports_dpc_native || host->native_aer))
> +	    (pcie_ports_native || pcie_ports_dpc_native || host->native_aer))
>  		services |= PCIE_PORT_SERVICE_DPC;

[Severity: High]
This isn't a bug introduced by this patch, but pre-existed in the codebase.
Since this patch correctly restores the pcie_ports_native override here,
should we also fix other subsystems that incorrectly check host->native_*
flags directly without honoring the command-line overrides?

For example, in drivers/cxl/core/ras.c:devm_cxl_dport_rch_ras_setup(),
the code drops the override, which can lead to broken error reporting for
uncorrectable errors:

	host_bridge = to_pci_host_bridge(dport->dport_dev);
	if (!host_bridge->native_aer)
		return;

	cxl_dport_map_rch_aer(dport);

Similarly, in drivers/pci/pci-acpi.c:pci_acpi_program_hpx_type2(), it
fails to account for the command line override which should prevent
programming when the OS forces AER:

	/*
	 * Only do the _HPX Type 2 programming if OS owns PCIe native
	 * hotplug but not AER.
	 */
	if (!host->native_pcie_hotplug || host->native_aer)
		return;

Also, in drivers/pci/pcie/dpc.c:pci_dpc_recovered(), this check bypasses
the synchronization wait if it fails to recognize OS-forced DPC
ownership:

	host = pci_find_host_bridge(pdev->bus);
	if (!host->native_dpc && !IS_ENABLED(CONFIG_PCIE_EDR))
		return false;

Because pci_dpc_recovered() prematurely returns false, the pciehp driver
will not ignore spurious Link Down/Up events during DPC. Does this cause
hotplug to incorrectly race with DPC recovery?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260901064554.2178688-1-kanie@linux.alibaba.com?part=1