[PATCH v3 3/8] perf test ibs: Skip privilege test on Zen6 and newer platforms

[Ravi Bangoria]

IBS on pre-Zen6 platforms lacked a hardware privilege filter, so the
kernel enabled swfilt=1. Zen6 and newer platforms provides privilege
filtering via the RIP[63] bit, making swfilt redundant. Skip the perf
unit test that assumes IBS has no hardware-assisted privilege filter
on Zen6 and newer platforms.

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 on Zen6:

  # sudo ./perf test -vv 77
   77: AMD IBS software filtering:
  --- start ---
  test child forked, pid 30813
  check availability of IBS swfilt
  run perf record with modifier and swfilt
  [FAIL] IBS PMU should not accept exclude_kernel
  ---- end(-1) ----
   77: AMD IBS software filtering                            : FAILED!

With the patch:

  # ./perf test -vv 77
   77: AMD IBS software filtering:
  --- start ---
  test child forked, pid 30903
  check availability of IBS swfilt
  run perf record with modifier and swfilt
  [ perf record: Woken up 2 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 4 times to write data ]
  [ perf record: Captured and wrote 0.051 MB - ]
  [ perf record: Woken up 4 times to write data ]
  [ perf record: Captured and wrote 0.063 MB - ]
  ---- end(0) ----
   77: AMD IBS software filtering                            : Ok

Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
---
 tools/perf/tests/shell/amd-ibs-swfilt.sh | 37 +++++++++++++++++++++---
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/tools/perf/tests/shell/amd-ibs-swfilt.sh b/tools/perf/tests/shell/amd-ibs-swfilt.sh
index e7f66df05c4b..e3738436773e 100755
--- a/tools/perf/tests/shell/amd-ibs-swfilt.sh
+++ b/tools/perf/tests/shell/amd-ibs-swfilt.sh
@@ -1,6 +1,33 @@
 #!/bin/bash
 # AMD IBS software filtering
 
+cpu_family() {
+    grep -m1 '^cpu family[[:space:]]*:' /proc/cpuinfo \
+        | awk -F: '{gsub(/^[ \t]+/, "", $2); print $2}'
+}
+
+cpu_model() {
+    grep -m1 '^model[[:space:]]*:' /proc/cpuinfo \
+        | awk -F: '{gsub(/^[ \t]+/, "", $2); print $2}'
+}
+
+# IBS PMUs does not advertize privilege filtering capability. Rely
+# on Family / Model check.
+hw_priv_filter_supported() {
+    family=$(cpu_family)
+    model=$(cpu_model)
+
+    if (( family > 0x1a )) ||
+       { (( family == 0x1a )) &&
+         { { (( model >= 0x50 && model <= 0x5f )) ||
+             (( model >= 0x80 && model <= 0xaf )) ||
+             (( model >= 0xc0 && model <= 0xcf )); }; }; }; then
+        return 0 # True
+    else
+        return 1 # False
+    fi
+}
+
 ParanoidAndNotRoot() {
   [ "$(id -u)" != 0 ] && [ "$(cat /proc/sys/kernel/perf_event_paranoid)" -gt $1 ]
 }
@@ -23,10 +50,12 @@ 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
+if ! hw_priv_filter_supported; then
+    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
 fi
 
 # setting it with swfilt should be fine
-- 
2.43.0