linux-kernel - Re: [PATCH v7 7/9] vfio-pci/zdev: Add a device feature for error information

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Message-ID: <af49850b-4c83-4847-a11f-deb864e4c691@linux.ibm.com>
Date: Tue, 20 Jan 2026 10:54:48 -0800
From: Farhan Ali <alifm@...ux.ibm.com>
To: Julian Ruess <julianr@...ux.ibm.com>, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Cc: helgaas@...nel.org, lukas@...ner.de, alex@...zbot.org, clg@...hat.com,
        stable@...r.kernel.org, schnelle@...ux.ibm.com, mjrosato@...ux.ibm.com
Subject: Re: [PATCH v7 7/9] vfio-pci/zdev: Add a device feature for error
 information


On 1/19/2026 8:24 AM, Julian Ruess wrote:
>> For zPCI devices, we have platform specific error information. The platform
>> firmware provides this error information to the operating system in an
>> architecture specific mechanism. To enable recovery from userspace for
>> these devices, we want to expose this error information to userspace. Add a
>> new device feature to expose this information.
>>
>> Signed-off-by: Farhan Ali<alifm@...ux.ibm.com>
>> ---
>>   drivers/vfio/pci/vfio_pci_core.c |  2 ++
>>   drivers/vfio/pci/vfio_pci_priv.h |  9 +++++++++
>>   drivers/vfio/pci/vfio_pci_zdev.c | 34 ++++++++++++++++++++++++++++++++
>>   include/uapi/linux/vfio.h        | 16 +++++++++++++++
>>   4 files changed, 61 insertions(+)
>>
>> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
>> index 3a11e6f450f7..f677705921e6 100644
>> --- a/drivers/vfio/pci/vfio_pci_core.c
>> +++ b/drivers/vfio/pci/vfio_pci_core.c
>> @@ -1526,6 +1526,8 @@ int vfio_pci_core_ioctl_feature(struct vfio_device *device, u32 flags,
>>   		return vfio_pci_core_feature_token(vdev, flags, arg, argsz);
>>   	case VFIO_DEVICE_FEATURE_DMA_BUF:
>>   		return vfio_pci_core_feature_dma_buf(vdev, flags, arg, argsz);
>> +	case VFIO_DEVICE_FEATURE_ZPCI_ERROR:
>> +		return vfio_pci_zdev_feature_err(device, flags, arg, argsz);
> Would it make sense to name this more generically, e.g.
> VFIO_DEVICE_FEATURE_ERROR_RECOVERY, in case other architectures also want to
> support something like this in the future?

The error recovery mechanism here and also the uapi structure exposed 
via this device feature is very specific to zPCI devices. Making this a 
generic device feature would mean having different uapi structure for 
zPCI devices vs PCI devices on other architectures. I am not sure that 
would be desirable and might be cleaner to have separate device feature 
and separate uapi constructs for zPCI vs other architectures.

Thanks

Farhan