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

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Date: Wed, 27 Mar 2024 15:20:50 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Joao Martins <joao.m.martins@...cle.com>
Cc: Muhammad Usama Anjum <usama.anjum@...labora.com>,
	Nicolin Chen <nicolinc@...dia.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 Wed, Mar 27, 2024 at 06:09:37PM +0000, 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 :(
> 
> Thus no bits are being set.

Oh! 

--- a/drivers/iommu/iommufd/Kconfig
+++ b/drivers/iommu/iommufd/Kconfig
@@ -37,6 +37,7 @@ config IOMMUFD_TEST
        depends on DEBUG_KERNEL
        depends on FAULT_INJECTION
        depends on RUNTIME_TESTING_MENU
+       select IOMMUFD_DRIVER
        default n
        help
          This is dangerous, do not enable unless running


???

Jason