[PATCH v3] perf evsel amd: Fix IBS error message

[Ravi Bangoria]

AMD IBS can do per-process profiling[1] and is no longer restricted to
per-cpu or systemwide only. Remove stale error message. Also, checking
just exclude_kernel is not sufficient since IBS does not support any
privilege filters. So include all exclude_* checks. And finally, move
these checks under tools/perf/arch/x86/ from generic code.

Before:
  $ sudo ./perf record -e ibs_op//k -C 0
  Error:
  AMD IBS may only be available in system-wide/per-cpu mode.  Try
  using -a, or -C and workload affinity

After:
  $ sudo ./perf record -e ibs_op//k -C 0
  Error:
  AMD IBS doesn't support privilege filtering. Try again without
  the privilege modifiers (like 'k') at the end.

[1] https://git.kernel.org/torvalds/c/30093056f7b2

Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxx>
---
v2: https://lore.kernel.org/r/20230626103958.834-1-ravi.bangoria@xxxxxxx
v2->v3:
  - Make error message more perf tool user friendly.

 tools/perf/arch/x86/util/evsel.c | 20 ++++++++++++++++++++
 tools/perf/util/evsel.c          | 30 +++++++++---------------------
 tools/perf/util/evsel.h          |  1 +
 3 files changed, 30 insertions(+), 21 deletions(-)

diff --git a/tools/perf/arch/x86/util/evsel.c b/tools/perf/arch/x86/util/evsel.c
index 512c2d885d24..af454fd07887 100644
--- a/tools/perf/arch/x86/util/evsel.c
+++ b/tools/perf/arch/x86/util/evsel.c
@@ -102,3 +102,23 @@ void arch__post_evsel_config(struct evsel *evsel, struct perf_event_attr *attr)
 		}
 	}
 }
+
+int arch_evsel__open_strerror(struct evsel *evsel, char *msg, size_t size)
+{
+	if (!x86__is_amd_cpu())
+		return 0;
+
+	if (!evsel->core.attr.precise_ip &&
+	    !(evsel->pmu_name && !strncmp(evsel->pmu_name, "ibs", 3)))
+		return 0;
+
+	/* More verbose IBS errors. */
+	if (evsel->core.attr.exclude_kernel || evsel->core.attr.exclude_user ||
+	    evsel->core.attr.exclude_hv || evsel->core.attr.exclude_idle ||
+	    evsel->core.attr.exclude_host || evsel->core.attr.exclude_guest) {
+		return scnprintf(msg, size, "AMD IBS doesn't support privilege filtering. Try "
+				 "again without the privilege modifiers (like 'k') at the end.");
+	}
+
+	return 0;
+}
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index f607b5bddc76..762e2b2634a5 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2924,25 +2924,19 @@ static bool find_process(const char *name)
 	return ret ? false : true;
 }
 
-static bool is_amd(const char *arch, const char *cpuid)
+int __weak arch_evsel__open_strerror(struct evsel *evsel __maybe_unused,
+				     char *msg __maybe_unused,
+				     size_t size __maybe_unused)
 {
-	return arch && !strcmp("x86", arch) && cpuid && strstarts(cpuid, "AuthenticAMD");
-}
-
-static bool is_amd_ibs(struct evsel *evsel)
-{
-	return evsel->core.attr.precise_ip
-	    || (evsel->pmu_name && !strncmp(evsel->pmu_name, "ibs", 3));
+	return 0;
 }
 
 int evsel__open_strerror(struct evsel *evsel, struct target *target,
 			 int err, char *msg, size_t size)
 {
-	struct perf_env *env = evsel__env(evsel);
-	const char *arch = perf_env__arch(env);
-	const char *cpuid = perf_env__cpuid(env);
 	char sbuf[STRERR_BUFSIZE];
 	int printed = 0, enforced = 0;
+	int ret;
 
 	switch (err) {
 	case EPERM:
@@ -3044,16 +3038,6 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
 			return scnprintf(msg, size,
 	"Invalid event (%s) in per-thread mode, enable system wide with '-a'.",
 					evsel__name(evsel));
-		if (is_amd(arch, cpuid)) {
-			if (is_amd_ibs(evsel)) {
-				if (evsel->core.attr.exclude_kernel)
-					return scnprintf(msg, size,
-	"AMD IBS can't exclude kernel events.  Try running at a higher privilege level.");
-				if (!evsel->core.system_wide)
-					return scnprintf(msg, size,
-	"AMD IBS may only be available in system-wide/per-cpu mode.  Try using -a, or -C and workload affinity");
-			}
-		}
 
 		break;
 	case ENODATA:
@@ -3063,6 +3047,10 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target,
 		break;
 	}
 
+	ret = arch_evsel__open_strerror(evsel, msg, size);
+	if (ret)
+		return ret;
+
 	return scnprintf(msg, size,
 	"The sys_perf_event_open() syscall returned with %d (%s) for event (%s).\n"
 	"/bin/dmesg | grep -i perf may provide additional information.\n",
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 9f06d6cd5379..848534ec74fa 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -311,6 +311,7 @@ void evsel__set_sample_id(struct evsel *evsel, bool use_sample_identifier);
 
 void arch_evsel__set_sample_weight(struct evsel *evsel);
 void arch__post_evsel_config(struct evsel *evsel, struct perf_event_attr *attr);
+int arch_evsel__open_strerror(struct evsel *evsel, char *msg, size_t size);
 
 int evsel__set_filter(struct evsel *evsel, const char *filter);
 int evsel__append_tp_filter(struct evsel *evsel, const char *filter);
-- 
2.41.0