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

From: <Ajish.Koshy@microchip.com>
To: <john.garry@huawei.com>, <jinpu.wang@ionos.com>,
	<Viswas.G@microchip.com>
Cc: <linux-scsi@vger.kernel.org>, <vishakhavc@google.com>,
	<ipylypiv@google.com>, <Ruksar.devadi@microchip.com>,
	<damien.lemoal@opensource.wdc.com>,
	<Vasanthalakshmi.Tharmarajan@microchip.com>
Subject: RE: [issue report] pm8001 issues (was driver crashes with IOMMU enabled)
Date: Thu, 13 Jan 2022 12:52:31 +0000	[thread overview]
Message-ID: <PH0PR11MB5112E3E9787F20EDEB58D481EC539@PH0PR11MB5112.namprd11.prod.outlook.com> (raw)
In-Reply-To: <75d042c1-cee5-ce91-e1cb-9e2b7bb1ce72@huawei.com>

Hi John,

> Hi Ajish,
> 
> >>
> >> 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
> 
> Your position on this is not clear on this one.
> 
>  From an earlier mail [0] I got the impression that you tested on an arm
> platform – did you?

Yes, with respect to my previous mail update, at that time got the chance to
load the driver on ARM server/enclosure connected in one of our tester's 
arm server after attaching the controller card.
There this error handling issue was observed.

The card/driver was never tested or validated on ARM server before,
was curious to see the behavior for the first time. Whereas driver
loads smoothly on x86 server.

Currently busy with some other issues, debugging on ARM server is not
planned for now.

> 
> I just don't know for certain that this is a card issue or an issue with the
> driver issue or both. I have a strong feeling that it is a driver issue. As I
> mentioned, v4.11 seems to work much better than v5.16 - on
> v4.11 I can mount the filesystem and copy files, which is not possible on a
> new kernel.
> 
> IIRC I did use this same card on an x86 platform some time and it worked ok,
> but I can't be certain. And it's really painful for me to swap the card to an x86
> machine to test.
> 
> > 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.
> 
> Your list looks ok. However I did also mention these logs which I saw on my
> arm machine:
> 
> [   12.160631] sas: target proto 0x0 at 500e004aaaaaaa1f:0x10 not handled
> [   12.167183] sas: ex 500e004aaaaaaa1f phy16 failed to discover
> 
> They are red flags, and may be related to 2, above.
> 
> Thanks,
> John
> 
> [0]
> https://lore.kernel.org/linux-
> scsi/PH0PR11MB51122D76F40E164C31AFEE54EC719@PH0PR11MB5112.nam
> prd11.prod.outlook.com/

Thanks,
Ajish