On Wed, 11 Jun 2025 17:28:28 -0500
Mario Limonciello <superm1@xxxxxxxxxx> wrote:
> From: Mario Limonciello <mario.limonciello@xxxxxxx>
>
> commit 4d4c10f763d7 ("PCI: Explicitly put devices into D0 when
> initializing") intended to put PCI devices into D0, but in doing so
> unintentionally changed runtime PM initialization not to occur on
> devices that don't support PCI PM. This caused a regression in vfio-pci
> due to an imbalance with it's use.
>
> Adjust the logic in pci_pm_init() so that even if PCI PM isn't supported
> runtime PM is still initialized.
>
> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Reported-by: Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx>
> Closes: https://lore.kernel.org/linux-pci/20250424043232.1848107-1-superm1@xxxxxxxxxx/T/#m7e8929d6421690dc8bd6dc639d86c2b4db27cbc4
> Reported-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx>
> Closes: https://lore.kernel.org/linux-pci/20250424043232.1848107-1-superm1@xxxxxxxxxx/T/#m40d277dcdb9be64a1609a82412d1aa906263e201
> Tested-by: Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx>
> Fixes: 4d4c10f763d7 ("PCI: Explicitly put devices into D0 when initializing")
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> drivers/pci/pci.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 3dd44d1ad829b..c495c3c692f5f 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -3221,15 +3221,17 @@ void pci_pm_init(struct pci_dev *dev)
>
> /* find PCI PM capability in list */
> pm = pci_find_capability(dev, PCI_CAP_ID_PM);
> - if (!pm)
> + if (!pm) {
> + goto poweron;
> return;
Unreachable return. Thanks,
Alex
> + }
> /* Check device's ability to generate PME# */
> pci_read_config_word(dev, pm + PCI_PM_PMC, &pmc);
>
> if ((pmc & PCI_PM_CAP_VER_MASK) > 3) {
> pci_err(dev, "unsupported PM cap regs version (%u)\n",
> pmc & PCI_PM_CAP_VER_MASK);
> - return;
> + goto poweron;
> }
>
> dev->pm_cap = pm;
> @@ -3274,6 +3276,7 @@ void pci_pm_init(struct pci_dev *dev)
> pci_read_config_word(dev, PCI_STATUS, &status);
> if (status & PCI_STATUS_IMM_READY)
> dev->imm_ready = 1;
> +poweron:
> pci_pm_power_up_and_verify_state(dev);
> pm_runtime_forbid(&dev->dev);
> pm_runtime_set_active(&dev->dev);
