RE: [issue report] pm8001 issues (was driver crashes with IOMMU enabled)

[<Ajish.Koshy@microchip.com>]

Hi John,

> >> Once the task is dispatched to HW at ****, it is completed async, i.e.
> >> it may be completed and freed at any point, even before the dispatch
> >> function returns. So it is illegal to touch the task at this point
> >> and the task state must be updated before final dispatch to the HW.
> >> If you enable KASAN you will prob see it yell like I saw.
> >>
> > I too have similar thought here. After dispatch to HW, no point to
> > touch the task state. But since the code is in IO path, may need further
> testing.
> >
> 
> Hi,
> 
> Have you made any progress on the hang which I see on my arm64 system?

Not planned for ARM server.

> 
> I think that you said that you can also see it on an arm64 system - would that
> be with a similar card to mine? I think mine is 8008/9

That was similar card i.e. 8076.

> 
> I have tested some older kernels and v4.11 seems much better.
> 
> Thanks,
> John

Just to get more clarification, in the same thread 
following issues were mentioned. Right now
I am on x86 server. Don't have 8008/8009 controller
with me here. 
Issues:
1. Driver crashes when IOMMU is enabled. Patch already
submitted.
   - Issue was seen on x86 server too.
2. Observed triggering of scsi error handler on
   ARM server.
   - Issue not observed on x86 server
3. maxcpus=1 on commandline crashes during bootup. 
   Issue with 8008/8009 controller. Patch created.
   - Issue impacts x86 too based on the code.
4. "I have found another issue. There is a potential
   use-after-free in pm8001_task_exec():", where we
   modify task state post task dispatch to hardware
   - Generic code. Impact on all platform x86 and ARM.
   
Let us know if any other issue missed out to
mention here or issues that impacts x86 too.

Thanks,
Ajish