In-field Scan: CPU online self-test support.

For more info, See: https://lwn.net/Articles/886510/

Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>

tests/ifs/ifs.c

@@ -0,0 +1,128 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ *
+ * Run 'In Field Scan' test provided by the Linux kernel on compatible hardware
+ *
+ * Requires `ifs.ko` to be loaded in the Linux kernel, as well as
+ * firmware test blob data in `/lib/firmware/...`. Supported since
+ * 5.17.0.
+ *
+ */
+
+#include <limits.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <pthread.h>
+
+#include <sandstone.h>
+
+static pthread_mutex_t scanmutex = PTHREAD_MUTEX_INITIALIZER;
+
+// static because we only every want to do this once per machine
+static bool initialized = false;
+
+#define BUFLEN 256 // kernel module prints at most a 64bit value
+
+static bool write_file(const char* filename, const char* value)
+{
+        size_t l = strlen(value);
+
+        int fd = open(filename, O_WRONLY);
+        if (fd == -1)
+                return false;
+        if (write(fd, value, l) != l) {
+                close(fd);
+                return false;
+        }
+        close(fd);
+        return true;
+}
+
+static int scan_init(struct test *test)
+{
+        // fracture may cause this function to be called several times.
+        if (initialized)
+                return 0;
+
+        initialized = true;
+
+        /* modprobe kernel driver, ignore errors entirely here */
+        IGNORE_RETVAL(system("/sbin/modprobe intel_ifs"));
+
+        /* first check if there is basic kernel support with the API we support */
+        if ((access("/sys/devices/system/cpu/ifs/run_test", W_OK) != 0) ||
+            (access("/sys/devices/system/cpu/cpu0/ifs/status", R_OK) != 0) != 0 ) {
+                log_info("not supported (missing kernel module, firmware, or invalid HW)");
+                return EXIT_SKIP;
+        }
+
+        if (!write_file("/sys/devices/system/cpu/ifs/run_test", "1\n")) {
+                log_info("run_test write failed");
+                return EXIT_SKIP;
+        }
+
+        return 0;
+}
+
+static int scan_run(struct test *test, int cpu)
+{
+        FILE *file;
+        char filename[PATH_MAX];
+        char result[BUFLEN];
+
+        pthread_mutex_lock(&scanmutex);
+
+        sprintf(filename, "/sys/devices/system/cpu/cpu%d/ifs/status", cpu_info[cpu].cpu_number);
+
+        for (;;) {
+                int r = 0;
+
+                file = fopen(filename, "r");
+                if (!file) {
+                        pthread_mutex_unlock(&scanmutex);
+                        log_info("status fopen(): %m");
+                        return EXIT_SKIP;
+                }
+                result[0] = 0;
+                if (!fgets(result, sizeof(result), file)) {
+                        int e = errno;
+                        pthread_mutex_unlock(&scanmutex);
+                        if (e == EBUSY) {
+                                if (r++ > 80) { // 2sec max
+                                        log_warning("timed out waiting for test to complete");
+                                        return EXIT_SKIP;
+                                }
+                                fclose(file);
+                                usleep(25000); // 25ms
+                                continue;
+                        }
+
+                        log_info("status fgets(): %m");
+                        return EXIT_SKIP;
+                }
+
+                fclose(file);
+                break;
+        }
+
+        pthread_mutex_unlock(&scanmutex);
+
+        if (strncmp(result, "fail", BUFLEN) == 0)
+                // core is defective, should be offlined by user
+                report_fail_msg("IFS: cpu failed self-test");
+
+        return 0;
+}
+
+DECLARE_TEST(ifs, "IFS hardware selftest")
+    .quality_level = TEST_QUALITY_BETA,
+    .test_init = scan_init,
+    .test_run = scan_run,
+    .desired_duration = -1,
+    .fracture_loop_count = -1,
+    .max_threads = 1,
+END_DECLARE_TEST

tests/meson.build

@@ -33,6 +33,12 @@ if target_machine.cpu_family() != 'x86_64'
 	tests_common_cpp_args += '-Wno-deprecated-copy'
 endif
 
+tests_base_set.add(
+	files(
+		'ifs/ifs.c',
+	)
+)
+
 eigen3_dep = dependency('eigen3', static : dep_static)
 tests_base_set.add(
 	when : eigen3_dep,
@@ -148,4 +154,4 @@ if host_machine.cpu_family() == 'x86_64'
 		tests_hsw_a,
 		tests_skx_a,
 	]
-endif
+endif