selftests/resctrl: Add vendor detection mechanism

RESCTRL feature is supported both on Intel and AMD now. Some features
are implemented differently. Add vendor detection mechanism. Use the vendor
check where there are differences.

Signed-off-by: Babu Moger <[e-mail]>
Co-developed-by: Fenghua Yu <[e-mail]>
Signed-off-by: Fenghua Yu <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/resctrl/resctrl.h

···
 int tests_run;
 
 char llc_occup_path[1024];
+bool is_amd;
 
 bool check_resctrlfs_support(void);
 int filter_dmesg(void);

tools/testing/selftests/resctrl/resctrl_tests.c

···
 #define BENCHMARK_ARGS		64
 #define BENCHMARK_ARG_SIZE	64
 
+bool is_amd;
+
+void detect_amd(void)
+{
+	FILE *inf = fopen("/proc/cpuinfo", "r");
+	char *res;
+
+	if (!inf)
+		return;
+
+	res = fgrep(inf, "vendor_id");
+
+	if (res) {
+		char *s = strchr(res, ':');
+
+		is_amd = s && !strcmp(s, ": AuthenticAMD\n");
+		free(res);
+	}
+	fclose(inf);
+}
+
 static void cmd_help(void)
 {
 	printf("usage: resctrl_tests [-h] [-b \"benchmark_cmd [options]\"] [-t test list] [-n no_of_bits]\n");
···
 	 */
 	if (geteuid() != 0)
 		printf("# WARNING: not running as root, tests may fail.\n");
+
+	/* Detect AMD vendor */
+	detect_amd();
 
 	if (has_ben) {
 		/* Extract benchmark command from command line. */