Message-Id: <D071OAFZ80O6.XEDXJ8AF4PK9@kernel.org>
Date: Sat, 30 Mar 2024 13:23:14 +0200
From: "Jarkko Sakkinen" <jarkko@...nel.org>
To: "Haitao Huang" <haitao.huang@...ux.intel.com>,
 <dave.hansen@...ux.intel.com>, <tj@...nel.org>, <mkoutny@...e.com>,
 <linux-kernel@...r.kernel.org>, <linux-sgx@...r.kernel.org>,
 <x86@...nel.org>, <cgroups@...r.kernel.org>, <tglx@...utronix.de>,
 <mingo@...hat.com>, <bp@...en8.de>, <hpa@...or.com>,
 <sohil.mehta@...el.com>, <tim.c.chen@...ux.intel.com>
Cc: <zhiquan1.li@...el.com>, <kristen@...ux.intel.com>, <seanjc@...gle.com>,
 <zhanb@...rosoft.com>, <anakrish@...rosoft.com>,
 <mikko.ylinen@...ux.intel.com>, <yangjie@...rosoft.com>,
 <chrisyan@...rosoft.com>
Subject: Re: [PATCH v9 15/15] selftests/sgx: Add scripts for EPC cgroup
 testing

On Thu Mar 28, 2024 at 2:57 AM EET, Haitao Huang wrote:
> On Wed, 27 Mar 2024 11:56:35 -0500, Jarkko Sakkinen <jarkko@...nel.org>  
> wrote:
>
> > On Wed Mar 27, 2024 at 2:55 PM EET, Jarkko Sakkinen wrote:
> >> On Mon, 2024-02-05 at 13:06 -0800, Haitao Huang wrote:
> >> > The scripts rely on cgroup-tools package from libcgroup [1].
> >> >
> >> > To run selftests for epc cgroup:
> >> >
> >> > sudo ./run_epc_cg_selftests.sh
> >> >
> >> > To watch misc cgroup 'current' changes during testing, run this in a
> >> > separate terminal:
> >> >
> >> > ./watch_misc_for_tests.sh current
> >> >
> >> > With different cgroups, the script starts one or multiple concurrent
> >> > SGX
> >> > selftests, each to run one unclobbered_vdso_oversubscribed test.> Each
> >> > of such test tries to load an enclave of EPC size equal to the EPC
> >> > capacity available on the platform. The script checks results against
> >> > the expectation set for each cgroup and reports success or failure.
> >> >
> >> > The script creates 3 different cgroups at the beginning with
> >> > following
> >> > expectations:
> >> >
> >> > 1) SMALL - intentionally small enough to fail the test loading an
> >> > enclave of size equal to the capacity.
> >> > 2) LARGE - large enough to run up to 4 concurrent tests but fail some
> >> > if
> >> > more than 4 concurrent tests are run. The script starts 4 expecting
> >> > at
> >> > least one test to pass, and then starts 5 expecting at least one test
> >> > to fail.
> >> > 3) LARGER - limit is the same as the capacity, large enough to run
> >> > lots of
> >> > concurrent tests. The script starts 8 of them and expects all pass.
> >> > Then it reruns the same test with one process randomly killed and
> >> > usage checked to be zero after all process exit.
> >> >
> >> > The script also includes a test with low mem_cg limit and LARGE
> >> > sgx_epc
> >> > limit to verify that the RAM used for per-cgroup reclamation is
> >> > charged
> >> > to a proper mem_cg.
> >> >
> >> > [1] https://github.com/libcgroup/libcgroup/blob/main/README
> >> >
> >> > Signed-off-by: Haitao Huang <haitao.huang@...ux.intel.com>
> >> > ---
> >> > V7:
> >> > - Added memcontrol test.
> >> >
> >> > V5:
> >> > - Added script with automatic results checking, remove the
> >> > interactive
> >> > script.
> >> > - The script can run independent from the series below.
> >> > ---
> >> >  .../selftests/sgx/run_epc_cg_selftests.sh     | 246
> >> > ++++++++++++++++++
> >> >  .../selftests/sgx/watch_misc_for_tests.sh     |  13 +
> >> >  2 files changed, 259 insertions(+)
> >> >  create mode 100755
> >> > tools/testing/selftests/sgx/run_epc_cg_selftests.sh
> >> >  create mode 100755
> >> > tools/testing/selftests/sgx/watch_misc_for_tests.sh
> >> >
> >> > diff --git a/tools/testing/selftests/sgx/run_epc_cg_selftests.sh
> >> > b/tools/testing/selftests/sgx/run_epc_cg_selftests.sh
> >> > new file mode 100755
> >> > index 000000000000..e027bf39f005
> >> > --- /dev/null
> >> > +++ b/tools/testing/selftests/sgx/run_epc_cg_selftests.sh
> >> > @@ -0,0 +1,246 @@
> >> > +#!/bin/bash
> >>
> >> This is not portable and neither does hold in the wild.
> >>
> >> It does not even often hold as it is not uncommon to place bash
> >> to the path /usr/bin/bash. If I recall correctly, e.g. NixOS has
> >> a path that is neither of those two.
> >>
> >> Should be #!/usr/bin/env bash
> >>
> >> That is POSIX compatible form.
> >>
> >> Just got around trying to test this in NUC7 so looking into this in
> >> more detail.
> >>
> >> That said can you make the script work with just "#!/usr/bin/env sh"
> >> and make sure that it is busybox ash compatible?
> >>
> >> I don't see any necessity to make this bash only and it adds to the
> >> compilation time of the image. Otherwise lot of this could be tested
> >> just with qemu+bzImage+busybox(inside initramfs).
> >>
> >> Now you are adding fully glibc shenanigans for the sake of syntax
> >> sugar.
> >>
> >> > +# SPDX-License-Identifier: GPL-2.0
> >> > +# Copyright(c) 2023 Intel Corporation.
> >> > +
> >> > +TEST_ROOT_CG=selftest
> >> > +cgcreate -g misc:$TEST_ROOT_CG
> >>
> >> How do you know that cgcreate exists? It is used a lot in the script
> >> with no check for the existence. Please fix e.g. with "command -v
> >> cgreate".
> >>
> >> > +if [ $? -ne 0 ]; then
> >> > +    echo "# Please make sure cgroup-tools is installed, and misc
> >> > cgroup is mounted."
> >> > +    exit 1
> >> > +fi
> >>
> >> And please do not do it this way. Also, please remove the advice for
> >> "cgroups-tool". This is not meant to be debian only. Better would be
> >> to e.g. point out the URL of the upstream project.
> >>
> >> And yeah the whole message should be based on "command -v", not like
> >> this.
> >>
> >> > +TEST_CG_SUB1=$TEST_ROOT_CG/test1
> >> > +TEST_CG_SUB2=$TEST_ROOT_CG/test2
> >> > +# We will only set limit in test1 and run tests in test3
> >> > +TEST_CG_SUB3=$TEST_ROOT_CG/test1/test3
> >> > +TEST_CG_SUB4=$TEST_ROOT_CG/test4
> >> > +
> >> > +cgcreate -g misc:$TEST_CG_SUB1
> >>
> >>
> >>
> >> > +cgcreate -g misc:$TEST_CG_SUB2
> >> > +cgcreate -g misc:$TEST_CG_SUB3
> >> > +cgcreate -g misc:$TEST_CG_SUB4
> >> > +
> >> > +# Default to V2
> >> > +CG_MISC_ROOT=/sys/fs/cgroup
> >> > +CG_MEM_ROOT=/sys/fs/cgroup
> >> > +CG_V1=0
> >> > +if [ ! -d "/sys/fs/cgroup/misc" ]; then
> >> > +    echo "# cgroup V2 is in use."
> >> > +else
> >> > +    echo "# cgroup V1 is in use."
> >>
> >> Is "#" prefix a standard for kselftest? I don't know this, thus asking.
> >>
> >> > +    CG_MISC_ROOT=/sys/fs/cgroup/misc
> >> > +    CG_MEM_ROOT=/sys/fs/cgroup/memory
> >> > +    CG_V1=1
> >>
> >> Have you checked what is the indentation policy for bash scripts inside
> >> kernel tree. I don't know what it is. That's why I'm asking.
> >>
> >> > +fi
> >> > +
> >> > +CAPACITY=$(grep "sgx_epc" "$CG_MISC_ROOT/misc.capacity" | awk
> >> > '{print $2}')
> >> > +# This is below number of VA pages needed for enclave of capacity
> >> > size. So
> >> > +# should fail oversubscribed cases
> >> > +SMALL=$(( CAPACITY / 512 ))
> >> > +
> >> > +# At least load one enclave of capacity size successfully, maybe up
> >> > to 4.
> >> > +# But some may fail if we run more than 4 concurrent enclaves of
> >> > capacity size.
> >> > +LARGE=$(( SMALL * 4 ))
> >> > +
> >> > +# Load lots of enclaves
> >> > +LARGER=$CAPACITY
> >> > +echo "# Setting up limits."
> >> > +echo "sgx_epc $SMALL" > $CG_MISC_ROOT/$TEST_CG_SUB1/misc.max
> >> > +echo "sgx_epc $LARGE" >  $CG_MISC_ROOT/$TEST_CG_SUB2/misc.max
> >> > +echo "sgx_epc $LARGER" > $CG_MISC_ROOT/$TEST_CG_SUB4/misc.max
> >> > +
> >> > +timestamp=$(date +%Y%m%d_%H%M%S)
> >> > +
> >> > +test_cmd="./test_sgx -t unclobbered_vdso_oversubscribed"
> >> > +
> >> > +wait_check_process_status() {
> >> > +    local pid=$1
> >> > +    local check_for_success=$2  # If 1, check for success;
> >> > +                                # If 0, check for failure
> >> > +    wait "$pid"
> >> > +    local status=$?
> >> > +
> >> > +    if [[ $check_for_success -eq 1 && $status -eq 0 ]]; then
> >> > +        echo "# Process $pid succeeded."
> >> > +        return 0
> >> > +    elif [[ $check_for_success -eq 0 && $status -ne 0 ]]; then
> >> > +        echo "# Process $pid returned failure."
> >> > +        return 0
> >> > +    fi
> >> > +    return 1
> >> > +}
> >> > +
> >> > +wai
> >> > wait_and_detect_for_any() {
> >>
> >> what is "any"?
> >>
> >> Maybe for some key functions could have short documentation what they
> >> are and for what test uses them. I cannot possibly remember all of this
> >> just by hints such as "this waits for Any" ;-)
> >>
> >> I don't think there is actual kernel guideline to engineer the script
> >> to work with just ash but at least for me that would inevitably
> >> increase my motivation to test this patch set more rather than less.
> >
> > I also wonder is cgroup-tools dependency absolutely required or could
> > you just have a function that would interact with sysfs?
>
> I should have checked email before hit the send button for v10 :-).
>
> It'd be more complicated and less readable to do all the stuff without the  
> cgroup-tools, esp cgexec. I checked dependency, cgroup-tools only depends  
> on libc so I hope this would not cause too much inconvenience.

As per cgroup-tools, please prove this. It makes the job for more
complicated *for you* and you are making the job more  complicated
to every possible person in the planet running any kernel QA.

I weight the latter more than the former. And it is exactly the
reason why we did custom user space kselftest in the first place.
Let's keep the tradition. All I can say is that kselftest is 
unfinished in its current form.

What is "esp cgexec"?


BR, Jarkko

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