linux-kernel - Re: [PATCH] selftests: iommu: add config needed for iommufd_fail

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Message-ID: <b05610de-f102-46d2-abe2-4e9ecbcd42eb@collabora.com>
Date: Wed, 27 Mar 2024 23:17:58 +0500
From: Muhammad Usama Anjum <usama.anjum@...labora.com>
To: Joao Martins <joao.m.martins@...cle.com>, Jason Gunthorpe <jgg@...pe.ca>,
 Nicolin Chen <nicolinc@...dia.com>
Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>, kernel@...labora.com,
 iommu@...ts.linux.dev, linux-kselftest@...r.kernel.org,
 linux-kernel@...r.kernel.org, Kevin Tian <kevin.tian@...el.com>,
 Shuah Khan <shuah@...nel.org>
Subject: Re: [PATCH] selftests: iommu: add config needed for iommufd_fail_nth

On 3/27/24 11:09 PM, Joao Martins wrote:
> On 27/03/2024 17:49, Muhammad Usama Anjum wrote:
>> On 3/27/24 7:59 PM, Joao Martins wrote:
>>> On 27/03/2024 11:49, Jason Gunthorpe wrote:
>>>> On Wed, Mar 27, 2024 at 03:14:25PM +0500, Muhammad Usama Anjum wrote:
>>>>> On 3/26/24 8:03 PM, Jason Gunthorpe wrote:
>>>>>> On Tue, Mar 26, 2024 at 06:09:34PM +0500, Muhammad Usama Anjum wrote:
>>>>>>> Even after applying this config patch and following snippet (which doesn't
>>>>>>> terminate the program if mmap doesn't allocate exactly as the hint), I'm
>>>>>>> finding failed tests.
>>>>>>>
>>>>>>> @@ -1746,7 +1748,7 @@ FIXTURE_SETUP(iommufd_dirty_tracking)
>>>>>>>         assert((uintptr_t)self->buffer % HUGEPAGE_SIZE == 0);
>>>>>>>         vrc = mmap(self->buffer, variant->buffer_size, PROT_READ | PROT_WRITE,
>>>>>>>                    mmap_flags, -1, 0);
>>>>>>> -       assert(vrc == self->buffer);
>>>>>>> +       assert(vrc == self->buffer);// ???
>>>>>>>
>>>>>>> On x86:
>>>>>>> # Totals: pass:176 fail:4 xfail:0 xpass:0 skip:0 error:0
>>>>>>> On ARM64:
>>>>>>> # Totals: pass:166 fail:14 xfail:0 xpass:0 skip:0 error:0
>>>>>>>
>>>>>>> The log files are attached.
>>>>>>
>>>>>> You probably don't have enough transparent huge pages available to the process
>>>>>>
>>>>>>       echo 1024 > /proc/sys/vm/nr_hugepages
>>>>> After making huge pages available, the iommufd test always passed on x86.
>>>>> But there are still failures on arm64. I'm looking into the failures.
>>>>
>>>> Oh that is really strange. Joao? Nicolin?
>>>>
>>> Definitely strange, I'll have a look.
>>>
>>> So it set the expected number of dirty bits as that assert doesn't fail, but it
>>> is failing when we check that even bits are set but not odd ones. Like it's
>>> hasn't set those bits.
>>>
>>> For mock tests there should be no difference between x86 and ARM assuming the
>>> typical 4K page-size. Maybe this is 64k base pages in ARM? That's the only thing
>>> that I can think of that affected mock domain.
>> The config is attached. The defaults are being used i.e., 4k page.
> 
> Looks like CONFIG_IOMMUFD_DRIVER is not defined :(
I'll retest with this config and update the patch to include it in the
config fragment needed for this test. Once we add all required config
options in config fragment, the test should never fail. Somehow this gets
included in the x86, but not on ARM.

> 
> Thus no bits are being set.
> 

-- 
BR,
Muhammad Usama Anjum