zdev: Add udev rule helper tool

Add an internal tool intended to be used by udev rules to determine
zdev and hypervisor related system information in key=value format.

Supported keys are:

  ZDEV_NEST_LEVEL=n
    Virtualization nesting level of running system

  ZDEV_HYPERVISOR_<n>=LPAR|z/VM|KVM/Linux
    Type of hypervisor that provides virtualization at nesting level <n>

  ZDEV_IS_DPM=0|1
    Indicator if top-level LPAR is managed by Dynamic Partition Manager

  ZDEV_NO_AUTO=0|1
    Indicator if auto-configuration is requested

Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdev/src/Makefile

@@ -73,7 +73,7 @@ lszdev_objects += lcs.o lcs_auto.o
 # Generic CCW devtype
 lszdev_objects += generic_ccw.o
 
-all: chzdev lszdev
+all: chzdev lszdev zdev_id
 
 chzdev_usage.c: chzdev_usage.txt
 	$(SED) $< >$@ -e 's/\\/\\\\/g' -e 's/"/\\"/g' -e 's/^/"/g' \
@@ -95,16 +95,17 @@ libs = $(rootdir)/libutil/libutil.a
 chzdev: $(chzdev_objects) $(libs)
 lszdev: $(lszdev_objects) $(libs)
 
-install: chzdev
+install: chzdev zdev_id
 	$(INSTALL) -d -m 755 $(DESTDIR)$(BINDIR)
 	$(INSTALL) -c chzdev $(DESTDIR)$(BINDIR)
 	$(INSTALL) -c lszdev $(DESTDIR)$(BINDIR)
+	$(INSTALL) -c zdev_id $(DESTDIR)$(TOOLS_LIBDIR)
 ifeq ($(HAVE_DRACUT),1)
 	$(INSTALL) -m 755 zdev-root-update.dracut \
 		$(DESTDIR)$(TOOLS_LIBDIR)/zdev-root-update
 endif
 
 clean:
-	@rm -f *.o chzdev lszdev chzdev_usage.c lszdev_usage.c gmon.out *.gcda *.gcno
+	@rm -f *.o chzdev lszdev chzdev_usage.c lszdev_usage.c gmon.out *.gcda *.gcno zdev_id
 
 .PHONY: all install clean

zdev/src/zdev_id.c

@@ -0,0 +1,154 @@
+/*
+ * zdev_id - Determine system characteristics required by zdev udev rules
+ *
+ * Copyright IBM Corp. 2021
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define	SYSINFO		"/proc/sysinfo"
+#define	CMDLINE		"/proc/cmdline"
+#define	WHITESPACE	" \t\n"
+
+static void array_add(char ***array_p, int *num_p, const char *str)
+{
+	char **array = *array_p, *copy;
+	int num = *num_p + 1;
+
+	array = realloc(array, num * sizeof(char *));
+	copy = strdup(str);
+	if (!array || !copy)
+		err(1, "Could not allocate memory");
+	array[num - 1] = copy;
+	*array_p = array;
+	*num_p = num;
+}
+
+static void array_free(char **array, int num)
+{
+	int i;
+
+	for (i = 0; i < num; i++)
+		free(array[i]);
+	free(array);
+}
+
+static void process_sysinfo(const char *filename)
+{
+	char *line = NULL, *substr, **cps = NULL;
+	int is_dpm = 0, num_cps = 0, level, i;
+	FILE *fd;
+	size_t n;
+
+	fd = fopen(filename, "r");
+	if (!fd)
+		err(1, "Could not open sysinfo file '%s'", filename);
+
+	while (getline(&line, &n, fd) != -1) {
+		if (sscanf(line, "LPAR %m[^:]", &substr) == 1) {
+			if (strcmp(substr, "UUID") == 0) {
+				/* Heuristic: only DPM LPARs have UUIDs. */
+				is_dpm = 1;
+			} else if (strcmp(substr, "Number") == 0) {
+				array_add(&cps, &num_cps, "LPAR");
+			}
+			free(substr);
+		} else if (sscanf(line, "VM%*d Control Program: %ms ",
+				  &substr) == 1) {
+			array_add(&cps, &num_cps, substr);
+			free(substr);
+		}
+	}
+
+	free(line);
+	fclose(fd);
+
+	/*
+	 * ZDEV_NEST_LEVEL=n
+	 *
+	 * Virtualization nesting level of running system:
+	 *  1: LPAR
+	 *  2: first level VM
+	 *  3: second level VM
+	 */
+	printf("ZDEV_NEST_LEVEL=%d\n", num_cps);
+
+	/*
+	 * ZDEV_HYPERVISOR_<n>=LPAR|z/VM|KVM/Linux
+	 *
+	 * Type of hypervisor that provides virtualization at nesting level <n>.
+	 */
+	for (i = 0; i < num_cps; i++) {
+		/* Sysinfo lists VMs in reverse order .*/
+		level = (i == 0) ? i : (num_cps - i);
+		printf("ZDEV_HYPERVISOR_%d=\"%s\"\n", i, cps[level]);
+	}
+	array_free(cps, num_cps);
+
+	/*
+	 * ZDEV_IS_DPM=0|1
+	 *
+	 * Indicator if top-level LPAR is managed by Dynamic Partition
+	 * Manager (DPM):
+	 *  0: Classic mode
+	 *  1: DPM mode
+	 */
+	printf("ZDEV_IS_DPM=%d\n", is_dpm);
+}
+
+static void process_cmdline(const char *filename)
+{
+	char *line = NULL, *substr, *next = NULL, *value;
+	int no_auto = 0;
+	size_t n;
+	FILE *fd;
+
+	fd = fopen(filename, "r");
+	if (!fd)
+		err(1, "Could not open cmdline file '%s'", filename);
+
+	if (getline(&line, &n, fd) == -1)
+		goto out;
+
+	for (substr = strtok_r(line, WHITESPACE, &next); substr;
+	     substr = strtok_r(NULL, WHITESPACE, &next)) {
+		if (sscanf(substr, "rd.zdev=%ms ", &value) != 1)
+			continue;
+		if (strstr(value, "no-auto"))
+			no_auto = 1;
+
+		free(value);
+	}
+
+out:
+	free(line);
+	fclose(fd);
+
+	/*
+	 * ZDEV_NO_AUTO=0|1
+	 *
+	 * Indicator if auto-configuration is requested.
+	 *  0: Perform auto-configuration
+	 *  1: Skip auto-configuration
+	 */
+	printf("ZDEV_NO_AUTO=%d\n", no_auto);
+}
+
+int main(int argc, char *argv[])
+{
+	char *sysinfo, *cmdline;
+
+	sysinfo = argc < 2 ? SYSINFO : argv[1];
+	cmdline = argc < 3 ? CMDLINE : argv[2];
+
+	process_sysinfo(sysinfo);
+	process_cmdline(cmdline);
+
+	return 0;
+}