Re: [PATCH v9 15/15] selftests/sgx: Add scripts for EPC cgroup testing

["Jarkko Sakkinen" <jarkko@kernel.org>]

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@linux.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?

BR, Jarkko