perf test: Add AMD IBS sw filter test

[PATCH v2] perf test: Add AMD IBS sw filter test

Posted by Namhyung Kim 6 months, 4 weeks ago

The kernel v6.14 added 'swfilt' to support privilege filtering in
software so that IBS can be used by regular users.  Add a test case in
x86 to verify the behavior.

  $ sudo perf test -vv 'IBS software filter'
  113: AMD IBS software filtering:
  --- start ---
  test child forked, pid 178826
  check availability of IBS swfilt
  run perf record with modifier and swfilt
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.000 MB /dev/null ]
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.000 MB /dev/null ]
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.000 MB /dev/null ]
  [ perf record: Woken up 0 times to write data ]
  [ perf record: Captured and wrote 0.000 MB /dev/null ]
  check number of samples with swfilt
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.037 MB - ]
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.041 MB - ]
  ---- end(0) ----
  113: AMD IBS software filtering                                      : Ok

Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/tests/shell/amd-ibs-swfilt.sh | 67 ++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100755 tools/perf/tests/shell/amd-ibs-swfilt.sh

diff --git a/tools/perf/tests/shell/amd-ibs-swfilt.sh b/tools/perf/tests/shell/amd-ibs-swfilt.sh
new file mode 100755
index 0000000000000000..83937aa687ccd859
--- /dev/null
+++ b/tools/perf/tests/shell/amd-ibs-swfilt.sh
@@ -0,0 +1,67 @@
+#!/bin/sh
+# AMD IBS software filtering
+
+echo "check availability of IBS swfilt"
+
+# check if IBS PMU is available
+if [ ! -d /sys/bus/event_source/devices/ibs_op ]; then
+    echo "[SKIP] IBS PMU does not exist"
+    exit 2
+fi
+
+# check if IBS PMU has swfilt format
+if [ ! -f /sys/bus/event_source/devices/ibs_op/format/swfilt ]; then
+    echo "[SKIP] IBS PMU does not have swfilt"
+    exit 2
+fi
+
+echo "run perf record with modifier and swfilt"
+
+# setting any modifiers should fail
+perf record -B -e ibs_op//u -o /dev/null true 2> /dev/null
+if [ $? -eq 0 ]; then
+    echo "[FAIL] IBS PMU should not accept exclude_kernel"
+    exit 1
+fi
+
+# setting it with swfilt should be fine
+perf record -B -e ibs_op/swfilt/u -o /dev/null true
+if [ $? -ne 0 ]; then
+    echo "[FAIL] IBS op PMU cannot handle swfilt for exclude_kernel"
+    exit 1
+fi
+
+# setting it with swfilt=1 should be fine
+perf record -B -e ibs_op/swfilt=1/k -o /dev/null true
+if [ $? -ne 0 ]; then
+    echo "[FAIL] IBS op PMU cannot handle swfilt for exclude_user"
+    exit 1
+fi
+
+# check ibs_fetch PMU as well
+perf record -B -e ibs_fetch/swfilt/u -o /dev/null true
+if [ $? -ne 0 ]; then
+    echo "[FAIL] IBS fetch PMU cannot handle swfilt for exclude_kernel"
+    exit 1
+fi
+
+# check system wide recording
+perf record -aB --synth=no -e ibs_op/swfilt/k -o /dev/null true
+if [ $? -ne 0 ]; then
+    echo "[FAIL] IBS op PMU cannot handle swfilt in system-wide mode"
+    exit 1
+fi
+
+echo "check number of samples with swfilt"
+
+kernel_sample=$(perf record -e ibs_op/swfilt/u -o- true | perf script -i- -F misc | grep -c ^K)
+if [ ${kernel_sample} -ne 0 ]; then
+    echo "[FAIL] unexpected kernel samples: " ${kernel_sample}
+    exit 1
+fi
+
+user_sample=$(perf record -e ibs_fetch/swfilt/k -o- true | perf script -i- -F misc | grep -c ^U)
+if [ ${user_sample} -ne 0 ]; then
+    echo "[FAIL] unexpected user samples: " ${user_sample}
+    exit 1
+fi
-- 
2.49.0.1151.ga128411c76-goog

Re: [PATCH v2] perf test: Add AMD IBS sw filter test

Posted by Ravi Bangoria 6 months, 4 weeks ago

Hi Namhyung,

On 24-May-25 5:57 AM, Namhyung Kim wrote:
> The kernel v6.14 added 'swfilt' to support privilege filtering in
> software so that IBS can be used by regular users.  Add a test case in
> x86 to verify the behavior.
> 
>   $ sudo perf test -vv 'IBS software filter'
>   113: AMD IBS software filtering:
>   --- start ---
>   test child forked, pid 178826
>   check availability of IBS swfilt
>   run perf record with modifier and swfilt
>   [ perf record: Woken up 3 times to write data ]
>   [ perf record: Captured and wrote 0.000 MB /dev/null ]
>   [ perf record: Woken up 3 times to write data ]
>   [ perf record: Captured and wrote 0.000 MB /dev/null ]
>   [ perf record: Woken up 3 times to write data ]
>   [ perf record: Captured and wrote 0.000 MB /dev/null ]
>   [ perf record: Woken up 0 times to write data ]
>   [ perf record: Captured and wrote 0.000 MB /dev/null ]
>   check number of samples with swfilt
>   [ perf record: Woken up 3 times to write data ]
>   [ perf record: Captured and wrote 0.037 MB - ]
>   [ perf record: Woken up 3 times to write data ]
>   [ perf record: Captured and wrote 0.041 MB - ]
>   ---- end(0) ----
>   113: AMD IBS software filtering                                      : Ok
> 
> Cc: Ravi Bangoria <ravi.bangoria@amd.com>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>

A minor nit below ...

> +echo "check number of samples with swfilt"
> +
> +kernel_sample=$(perf record -e ibs_op/swfilt/u -o- true | perf script -i- -F misc | grep -c ^K)

"true" barely runs in userspace. So, many a times this "perf record"
generates no samples :)

Thanks,
Ravi

Re: [PATCH v2] perf test: Add AMD IBS sw filter test

Posted by Arnaldo Carvalho de Melo 6 months, 3 weeks ago

On Sat, May 24, 2025 at 03:17:13PM +0530, Ravi Bangoria wrote:
> Hi Namhyung,
> 
> On 24-May-25 5:57 AM, Namhyung Kim wrote:
> > The kernel v6.14 added 'swfilt' to support privilege filtering in
> > software so that IBS can be used by regular users.  Add a test case in
> > x86 to verify the behavior.
> > 
> >   $ sudo perf test -vv 'IBS software filter'
> >   113: AMD IBS software filtering:
> >   --- start ---
> >   test child forked, pid 178826
> >   check availability of IBS swfilt
> >   run perf record with modifier and swfilt
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   [ perf record: Woken up 0 times to write data ]
> >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> >   check number of samples with swfilt
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.037 MB - ]
> >   [ perf record: Woken up 3 times to write data ]
> >   [ perf record: Captured and wrote 0.041 MB - ]
> >   ---- end(0) ----
> >   113: AMD IBS software filtering                                      : Ok
> > 
> > Cc: Ravi Bangoria <ravi.bangoria@amd.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> 
> Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
> 
> A minor nit below ...
> 
> > +echo "check number of samples with swfilt"
> > +
> > +kernel_sample=$(perf record -e ibs_op/swfilt/u -o- true | perf script -i- -F misc | grep -c ^K)
> 
> "true" barely runs in userspace. So, many a times this "perf record"
> generates no samples :)

Right, something else, maybe one of those workloads:

acme@number:~/git/perf-tools-next$ perf test --list-workloads
noploop
thloop
leafloop
sqrtloop
brstack
datasym
landlock
acme@number:~/git/perf-tools-next$

root@number:~# time perf record -e ibs_op/swfilt/u perf test -w sqrtloop
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.160 MB perf.data (3976 samples) ]

real	0m1.588s
user	0m1.407s
sys	0m0.161s
root@number:~# perf script | wc -l
3976
root@number:~#

But I'm applying the patch as is, we can replace the workload later.

- Arnaldo

Re: [PATCH v2] perf test: Add AMD IBS sw filter test

Posted by Namhyung Kim 6 months, 3 weeks ago

On Tue, May 27, 2025 at 05:51:21PM -0300, Arnaldo Carvalho de Melo wrote:
> On Sat, May 24, 2025 at 03:17:13PM +0530, Ravi Bangoria wrote:
> > Hi Namhyung,
> > 
> > On 24-May-25 5:57 AM, Namhyung Kim wrote:
> > > The kernel v6.14 added 'swfilt' to support privilege filtering in
> > > software so that IBS can be used by regular users.  Add a test case in
> > > x86 to verify the behavior.
> > > 
> > >   $ sudo perf test -vv 'IBS software filter'
> > >   113: AMD IBS software filtering:
> > >   --- start ---
> > >   test child forked, pid 178826
> > >   check availability of IBS swfilt
> > >   run perf record with modifier and swfilt
> > >   [ perf record: Woken up 3 times to write data ]
> > >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> > >   [ perf record: Woken up 3 times to write data ]
> > >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> > >   [ perf record: Woken up 3 times to write data ]
> > >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> > >   [ perf record: Woken up 0 times to write data ]
> > >   [ perf record: Captured and wrote 0.000 MB /dev/null ]
> > >   check number of samples with swfilt
> > >   [ perf record: Woken up 3 times to write data ]
> > >   [ perf record: Captured and wrote 0.037 MB - ]
> > >   [ perf record: Woken up 3 times to write data ]
> > >   [ perf record: Captured and wrote 0.041 MB - ]
> > >   ---- end(0) ----
> > >   113: AMD IBS software filtering                                      : Ok
> > > 
> > > Cc: Ravi Bangoria <ravi.bangoria@amd.com>
> > > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > 
> > Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
> > 
> > A minor nit below ...
> > 
> > > +echo "check number of samples with swfilt"
> > > +
> > > +kernel_sample=$(perf record -e ibs_op/swfilt/u -o- true | perf script -i- -F misc | grep -c ^K)
> > 
> > "true" barely runs in userspace. So, many a times this "perf record"
> > generates no samples :)
> 
> Right, something else, maybe one of those workloads:
> 
> acme@number:~/git/perf-tools-next$ perf test --list-workloads
> noploop
> thloop
> leafloop
> sqrtloop
> brstack
> datasym
> landlock
> acme@number:~/git/perf-tools-next$
> 
> root@number:~# time perf record -e ibs_op/swfilt/u perf test -w sqrtloop
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.160 MB perf.data (3976 samples) ]
> 
> real	0m1.588s
> user	0m1.407s
> sys	0m0.161s
> root@number:~# perf script | wc -l
> 3976
> root@number:~#
> 
> But I'm applying the patch as is, we can replace the workload later.

Thanks, I can add some workload to create both kernel and user traffic.
I think the current workloads run in user space mostly.

Thanks,
Namhyung