Re: [PATCH v6 2/3] drivers/vfio: EEH support for VFIO PCI device

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Fri, May 23, 2014 at 08:55:15AM +0200, Alexander Graf wrote:
>> Am 23.05.2014 um 06:37 schrieb Gavin Shan <gwshan@linux.vnet.ibm.com>:
>>> On Thu, May 22, 2014 at 09:10:53PM -0600, Alex Williamson wrote:
>>>> On Thu, 2014-05-22 at 18:23 +1000, Gavin Shan wrote:
>>>> The patch adds new IOCTL commands for VFIO PCI device to support
>>>> EEH functionality for PCI devices, which have been passed through
>>>> from host to somebody else via VFIO.

.../...

>>>> +
>>>> +/*
>>>> + * Reset is the major step to recover problematic PE. The following
>>>> + * command helps on that.
>>>> + */
>>>> +struct vfio_eeh_pe_reset {
>>>> +    __u32 argsz;
>>>> +    __u32 option;
>>>> +};
>>>> +
>>>> +#define VFIO_EEH_PE_RESET        _IO(VFIO_TYPE, VFIO_BASE + 24)
>>>> +
>>>> +/*
>>>> + * One of the steps for recovery after PE reset is to configure the
>>>> + * PCI bridges affected by the PE reset.
>>>> + */
>>>> +#define VFIO_EEH_PE_CONFIGURE        _IO(VFIO_TYPE, VFIO_BASE + 25)
>>> 
>>> What can the user do differently by making these separate ioctls?
>> 
>> hrm, I didn't understood as well. Alex.G could have the explaination.
>
>Alex raised the same concern as me: why separate reset and configure? When we want to recover a device, we need a reset call anyway, right?
>

Ok. With current ioctl commands, "reset+configure" is required to do
error recovery. Before the recovery, we also need call "configure"
in order to retrieve error log correctly.

Also, they corresponds to 2 separate RTAS services: "ibm,set-slot-reset"
and "ibm,configure-pe".

Thanks,
Gavin