Re: [PATCH v2 1/2] PCI: dwc: Allow drivers to skip MEM outbound iATU setup

[sashiko-bot@kernel.org]

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

Pre-existing issues:
- [High] Callers of dw_pcie_setup_rc() ignore its return value, missing potential errors.
--

commit b48f3b5259744f25f4f7ea094bd8ed4860783aa6
Author: Xincheng Zhang <zhangxincheng@ultrarisc.com>

PCI: dwc: Allow drivers to skip MEM outbound iATU setup

This commit adds a flag to bypass outbound iATU programming for
identity-mapped MEM ranges on DWC controllers. It introduces a check
that returns -EINVAL if a skipped MEM range is not identity-mapped.

> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -918,6 +918,20 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
>  		atu.parent_bus_addr = entry->res->start - pci->parent_bus_offset;
>  		atu.pci_addr = entry->res->start - entry->offset;
>  
> +		if (pp->bypass_ob_mem_iatu) {
> +			/*
> +			 * The no-match pass-through path preserves the correct
> +			 * PCI address only for identity-mapped MEM ranges.
> +			 */
> +			if (atu.parent_bus_addr != atu.pci_addr) {
> +				dev_err(pci->dev,
> +					"Cannot bypass outbound iATU for non-identity MEM range %pr\n",
> +					entry->res);
> +				return -EINVAL;

[Severity: High]
This isn't a bug introduced by this patch, but adding this new failure path
highlights that callers of dw_pcie_setup_rc() (which calls
dw_pcie_iatu_setup()) ignore its return value.

For example, in drivers/pci/controller/dwc/pcie-designware-host.c during
system resume:

dw_pcie_resume_noirq() {
    ...
    dw_pcie_setup_rc(&pci->pp);
    ...
}

The core suspend/resume framework ignores the setup return value here.
The same pattern exists in driver-specific functions like
exynos_pcie_resume_noirq(), tegra_pcie_dw_resume_noirq(), and
tegra_pcie_dw_start_link().

If dw_pcie_setup_rc() fails because of an invalid ATU configuration
(like this new -EINVAL path) or an iATU enablement timeout, the controller
proceeds with link initialization without proper configuration. Missing
outbound memory windows or broken MSI can result in system crashes or silent
I/O failures when accessing PCI memory.

Could the callers of dw_pcie_setup_rc() be updated to check and handle
these failures appropriately?

> +			}
> +			continue;
> +		}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260905025635.211390-1-zhangxincheng@ultrarisc.com?part=1