linux-kernel - [PATCH 2/6] perf test ibs: Remove obsolete privilege test

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Message-ID: <20260119024328.897-3-ravi.bangoria@amd.com>
Date: Mon, 19 Jan 2026 02:43:23 +0000
From: Ravi Bangoria <ravi.bangoria@....com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>
CC: Ravi Bangoria <ravi.bangoria@....com>, Arnaldo Carvalho de Melo
	<acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, Ian Rogers
	<irogers@...gle.com>, Dapeng Mi <dapeng1.mi@...ux.intel.com>, James Clark
	<james.clark@...aro.org>, <x86@...nel.org>,
	<linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>, "Manali
 Shukla" <manali.shukla@....com>, Santosh Shukla <santosh.shukla@....com>,
	Ananth Narayan <ananth.narayan@....com>, Sandipan Das <sandipan.das@....com>
Subject: [PATCH 2/6] perf test ibs: Remove obsolete privilege test

Older IBS implementations lacked a hardware privilege filter, so the
kernel enabled swfilt=1. Newer AMD CPUs will provide privilege filtering
via the RIP[63] bit, making swfilt redundant. Remove the perf unit test
that assumes IBS has no hardware-assisted privilege filter.

swfilt is ignored by kernel on platforms that support RIP[63] bit filter
i.e. all amd-ibs-swfilt.sh tests will test hardware assisted privilege
filter.

Without the patch:

  # ./perf test -vv 75
  test child forked, pid 26029
  check availability of IBS swfilt
  run perf record with modifier and swfilt
  [FAIL] IBS PMU should not accept exclude_kernel
   75: AMD IBS software filtering                            : FAILED!

With the patch:

  # ./perf test -vv 75
  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 1 times to write data ]
  [ perf record: Captured and wrote 0.000 MB /dev/null ]
  check number of samples with swfilt
  [ perf record: Woken up 5 times to write data ]
  [ perf record: Captured and wrote 0.040 MB - ]
  [ perf record: Woken up 3 times to write data ]
  [ perf record: Captured and wrote 0.054 MB - ]
   75: AMD IBS software filtering                            : Ok

Signed-off-by: Ravi Bangoria <ravi.bangoria@....com>
---
 tools/perf/tests/shell/amd-ibs-swfilt.sh | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/tools/perf/tests/shell/amd-ibs-swfilt.sh b/tools/perf/tests/shell/amd-ibs-swfilt.sh
index e7f66df05c4b..92ef45bf3043 100755
--- a/tools/perf/tests/shell/amd-ibs-swfilt.sh
+++ b/tools/perf/tests/shell/amd-ibs-swfilt.sh
@@ -22,13 +22,6 @@ fi
 echo "run perf record with modifier and swfilt"
 err=0
 
-# 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
-- 
2.43.0