linux-kernel - Re: [PATCH v1 2/2] iommu/tegra-smmu: Revert workaround that was needed for Nyan Big Chromebook

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Message-ID: <19834018-4ac7-a8fd-f7df-199128b04e4e@gmail.com>
Date:   Mon, 26 Apr 2021 10:39:25 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Guillaume Tucker <guillaume.tucker@...labora.com>,
        Nicolin Chen <nicoleotsuka@...il.com>,
        Joerg Roedel <joro@...tes.org>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Krishna Reddy <vdumpa@...dia.com>,
        Will Deacon <will@...nel.org>,
        iommu@...ts.linux-foundation.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 2/2] iommu/tegra-smmu: Revert workaround that was
 needed for Nyan Big Chromebook

26.04.2021 10:14, Thierry Reding пишет:
> On Sat, Apr 24, 2021 at 11:27:10PM +0300, Dmitry Osipenko wrote:
>> 23.04.2021 18:23, Dmitry Osipenko пишет:
>>> 23.04.2021 18:01, Guillaume Tucker пишет:
>>>> On 02/04/2021 15:40, Dmitry Osipenko wrote:
>>>>> 01.04.2021 11:55, Nicolin Chen пишет:
>>>>>> On Mon, Mar 29, 2021 at 02:32:56AM +0300, Dmitry Osipenko wrote:
>>>>>>> The previous commit fixes problem where display client was attaching too
>>>>>>> early to IOMMU during kernel boot in a multi-platform kernel configuration
>>>>>>> which enables CONFIG_ARM_DMA_USE_IOMMU=y. The workaround that helped to
>>>>>>> defer the IOMMU attachment for Nyan Big Chromebook isn't needed anymore,
>>>>>>> revert it.
>>>>>>
>>>>>> Sorry for the late reply. I have been busy with downstream tasks.
>>>>>>
>>>>>> I will give them a try by the end of the week. Yet, probably it'd
>>>>>> be better to include Guillaume also as he has the Nyan platform.
>>>>>>
>>>>>
>>>>> Indeed, thanks. Although, I'm pretty sure that it's the same issue which
>>>>> I reproduced on Nexus 7.
>>>>>
>>>>> Guillaume, could you please give a test to these patches on Nyan Big?
>>>>> There should be no EMEM errors in the kernel log with this patches.
>>>>>
>>>>> https://patchwork.ozlabs.org/project/linux-tegra/list/?series=236215
>>>>
>>>> So sorry for the very late reply.  I have tried the patches but
>>>> hit some issues on linux-next, it's not reaching a login prompt
>>>> with next-20210422.  So I then tried with next-20210419 which
>>>> does boot but shows the IOMMU error:
>>>>
>>>> <6>[    2.995341] tegra-dc 54200000.dc: Adding to iommu group 1
>>>> <4>[    3.001070] Failed to attached device 54200000.dc to IOMMU_mapping  
>>>>
>>>>   https://lava.collabora.co.uk/scheduler/job/3570052#L1120
>>>>
>>>> The branch I'm using with the patches applied can be found here:
>>>>
>>>>   https://gitlab.collabora.com/gtucker/linux/-/commits/next-20210419-nyan-big-drm-read/
>>>>
>>>> Hope this helps, let me know if you need anything else to be
>>>> tested.
>>>
>>>
>>> Hello Guillaume,
>>>
>>> The current linux-next doesn't boot on all ARM (AFAIK), the older
>>> next-20210413 works. The above message should be unrelated to the boot
>>> problem. It should be okay to ignore that message as it should be
>>> harmless in yours case.
>>>
>>
>> Although, the 20210419 should be good.
>>
>> Thierry, do you know what those SOR and Nouveau issues are about?
> 
> There's a use-after-free (though it's really a use-before-init) issue in
> linux-next at the moment, but a fix has been suggested. The fix for this
> along with an additional leak plug is here:
> 
> 	http://patchwork.ozlabs.org/project/linux-tegra/list/?series=240569

Nice, thank you. Maybe Guillaume could give it a test.

> I'm not aware of any Nouveau issues. What version and platform are those
> happening on? Are there any logs? I can't seem to find them in this
> thread.

This all is on Nyan Big using linux-next-20210419. There is a link to the full log above.

I see this Nouveau failure:

<6>[   19.323113] nouveau 57000000.gpu: Adding to iommu group 2
<6>[   19.323615] nouveau 57000000.gpu: NVIDIA GK20A (0ea000a1)
<6>[   19.323668] nouveau 57000000.gpu: imem: using IOMMU
<3>[   19.323795] nouveau 57000000.gpu: gr ctor failed: -2
<4>[   19.323983] nouveau: probe of 57000000.gpu failed with error -2