Re: [PATCH v9 3/5] PCI: host-common: Add link down handling for Root Ports

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] Silent device state corruption on link recovery when AER is disabled.
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--- Patch [3]: [PATCH v9 3/5] PCI: host-common: Add link down handling for Root Ports ---
commit f0b63bf7d7d526d3c654256d686360e1e2906b25
Author: Manivannan Sadhasivam <mani@kernel.org>

PCI: host-common: Add link down handling for Root Ports

This commit introduces a new API pci_host_handle_link_down() to recover PCI
links that go down. It uses pcie_do_recovery() for AER-enabled kernels to
handle fatal errors and coordinate downstream driver recovery. For kernels
without AER, it falls back to resetting the root port directly.

> diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
> index 2ce6f4b661334..363d3f970b10c 100644
> --- a/drivers/pci/controller/pci-host-common.c
> +++ b/drivers/pci/controller/pci-host-common.c

[ ... ]

> +static void pci_host_recover_root_port(struct pci_dev *port)
> +{
> +#if IS_ENABLED(CONFIG_PCIEAER)
> +	pcie_do_recovery(port, pci_channel_io_frozen, pci_host_reset_root_port);
> +#else
> +	pci_host_reset_root_port(port);

[Severity: High]
Without AER enabled, this falls back to calling pci_host_reset_root_port(),
which resets the downstream bus using pci_bus_error_reset().

Because pci_bus_error_reset() utilizes PCI_RESET_NO_RESTORE, does this wipe
the configuration space (BARs, MSI, Memory/Bus Master Enable) of all
downstream devices?

Since pcie_do_recovery() is bypassed in this branch, downstream drivers are
never notified via slot_reset callbacks to restore their configuration state.
Could those drivers remain active and continue attempting MMIO accesses to
unmapped or disabled memory regions, leading to Master Aborts, timeouts,
or kernel crashes?

> +#endif
> +}
> +
> +void pci_host_handle_link_down(struct pci_dev *port)
> +{
> +	pci_info(port, "Recovering Root Port due to Link Down\n");
> +	pci_host_recover_root_port(port);
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260729-pci-port-reset-v9-0-53570b92064d@oss.qualcomm.com?part=3