Re: [PATCH v4 2/2] PCI: Put PCIe bridges with downstream devices into D3 at hibernate

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] pci: config space corruption on hibernation abort due to missing D3 guard
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commit 99f9dafa720163cc3dfac6ce20da883f888fb896
Author: Mario Limonciello (AMD) <superm1@kernel.org>

PCI: Put PCIe bridges with downstream devices into D3 at hibernate

During S3 suspend, pci_pm_suspend_noirq() puts PCIe bridges with
downstream devices into a low-power state. This commit aligns the
hibernate poweroff_noirq flow to use pci_pm_suspend_noirq_common(),
ensuring bridges with active children are also put into D3.

> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
[ ... ]
> @@ -1280,8 +1283,9 @@ static int pci_pm_poweroff_noirq(struct device *dev)
>  			return error;
>  	}
>  
> -	if (!pci_dev->state_saved && !pci_has_subordinate(pci_dev))
> -		pci_prepare_to_sleep(pci_dev);
> +	skip_bus_pm = pci_pm_suspend_noirq_common(pci_dev);

[Severity: High]
Could this lead to configuration space corruption if a hibernation aborts?

If a driver's poweroff_noirq callback puts the device into a low-power
state (like D3) but fails to save its state, calling
pci_pm_suspend_noirq_common() here will unconditionally invoke
pci_save_state().

Because the device is already in D3, reading the configuration registers
in pci_save_state() will populate saved_config_space with 0xFFFFFFFF
garbage.

If the hibernation process subsequently aborts, the PM core executes
pci_pm_restore_noirq(), which will blindly write this 0xFFFFFFFF garbage
back to the device's configuration registers (BARs, command registers, etc).
This will likely cause a system crash upon subsequent memory-mapped I/O
access.

Does pci_pm_poweroff_noirq() need the same explicit D3 safety guard that
the S3 suspend_noirq path uses to prevent reading config space from a
powered-down device?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260916051034.180226-1-mario.limonciello@amd.com?part=2