Re: [PATCH v2] PCI: Explicitly put devices into D0 when initializing - Bug report

[Mario Limonciello <superm1@kernel.org>]

On 6/11/2025 5:52 AM, Cabiddu, Giovanni wrote:
> Hi Mario, Bjorn and Alex,
> 
> On Wed, Apr 23, 2025 at 11:31:32PM -0500, Mario Limonciello wrote:
>> From: Mario Limonciello <mario.limonciello@amd.com>
>>
>> AMD BIOS team has root caused an issue that NVME storage failed to come
>> back from suspend to a lack of a call to _REG when NVME device was probed.
>>
>> commit 112a7f9c8edbf ("PCI/ACPI: Call _REG when transitioning D-states")
>> added support for calling _REG when transitioning D-states, but this only
>> works if the device actually "transitions" D-states.
>>
>> commit 967577b062417 ("PCI/PM: Keep runtime PM enabled for unbound PCI
>> devices") added support for runtime PM on PCI devices, but never actually
>> 'explicitly' sets the device to D0.
>>
>> To make sure that devices are in D0 and that platform methods such as
>> _REG are called, explicitly set all devices into D0 during initialization.
>>
>> Fixes: 967577b062417 ("PCI/PM: Keep runtime PM enabled for unbound PCI devices")
>> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
>> ---
> Through a bisect, we identified that this patch, in v6.16-rc1,
> introduces a regression on vfio-pci across all Intel QuickAssist (QAT)
> devices. Specifically, the ioctl VFIO_GROUP_GET_DEVICE_FD call fails
> with -EACCES.
> 
> Upon further investigation, the -EACCES appears to originate from the
> rpm_resume() function, which is called by pm_runtime_resume_and_get()
> within vfio_pci_core_enable(). Here is the exact call trace:
> 
>      drivers/base/power/runtime.c: rpm_resume()
>      drivers/base/power/runtime.c: __pm_runtime_resume()
>      include/linux/pm_runtime.h: pm_runtime_resume_and_get()
>      drivers/vfio/pci/vfio_pci_core.c: vfio_pci_core_enable()
>      drivers/vfio/pci/vfio_pci.c: vfio_pci_open_device()
>      drivers/vfio/vfio_main.c: device->ops->open_device()
>      drivers/vfio/vfio_main.c: vfio_df_device_first_open()
>      drivers/vfio/vfio_main.c: vfio_df_open()
>      drivers/vfio/group.c: vfio_df_group_open()
>      drivers/vfio/group.c: vfio_device_open_file()
>      drivers/vfio/group.c: vfio_group_ioctl_get_device_fd()
>      drivers/vfio/group.c: vfio_group_fops_unl_ioctl(..., VFIO_GROUP_GET_DEVICE_FD, ...)
> 
> Is this a known issue that affects other devices? Is there any ongoing
> discussion or fix in progress?
> 
> Thanks,
> 

This is the first I've heard about an issue with that patch.

Does setting the VFIO parameter disable_idle_d3 help?

If so; this feels like an imbalance of runtime PM calls in the VFIO 
stack that this patch exposed.

Alex, any ideas?