From b76e95b51a53dafb2a9675d07bc1e08fa1ff1dc8 Mon Sep 17 00:00:00 2001
From: Jin Kyu Song <jin.kyu.song@intel.com>
Date: Wed, 8 May 2013 12:03:55 -0700
Subject: [PATCH] Add '-a' option for writing values to an MSR on all cpus

Signed-off-by: Jin Kyu Song <jin.kyu.song@intel.com>
---
 wrmsr.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 51 insertions(+), 7 deletions(-)

diff --git a/wrmsr.c b/wrmsr.c
index ab87921..8a601b9 100644
--- a/wrmsr.c
+++ b/wrmsr.c
@@ -25,17 +25,20 @@
 #include <getopt.h>
 #include <inttypes.h>
 #include <sys/types.h>
+#include <dirent.h>
+#include <ctype.h>
 
 #include "version.h"
 
 static const struct option long_options[] = {
 	{"help",	0, 0, 'h'},
 	{"version",	0, 0, 'V'},
+	{"all",		0, 0, 'a'},
 	{"processor",	1, 0, 'p'},
 	{"cpu",		1, 0, 'p'},
 	{0, 0, 0, 0}
 };
-static const char short_options[] = "hVp:";
+static const char short_options[] = "hVap:";
 
 const char *program;
 
@@ -44,20 +47,43 @@ void usage(void)
 	fprintf(stderr, "Usage: %s [options] regno value...\n"
 		"  --help         -h  Print this help\n"
 		"  --version      -V  Print current version\n"
+		"  --all          -a  all processors\n"
 		"  --processor #  -p  Select processor number (default 0)\n",
 		program);
 }
 
+void wrmsr_on_cpu(uint32_t reg, int cpu, int valcnt, char *regvals[]);
+
+/* filter out ".", "..", "microcode" in /dev/cpu */
+int dir_filter(const struct dirent *dirp)
+{
+	if (isdigit(dirp->d_name[0]))
+		return 1;
+	else
+		return 0;
+}
+
+void wrmsr_on_all_cpus(uint32_t reg, int valcnt, char *regvals[])
+{
+	struct dirent **namelist;
+	int dir_entries;
+
+	dir_entries = scandir("/dev/cpu", &namelist, dir_filter, 0);
+	while (dir_entries--) {
+		wrmsr_on_cpu(reg, atoi(namelist[dir_entries]->d_name),
+				valcnt, regvals);
+		free(namelist[dir_entries]);
+	}
+	free(namelist);
+}
+
 int main(int argc, char *argv[])
 {
 	uint32_t reg;
-	uint64_t data;
-	int fd;
 	int c;
 	int cpu = 0;
 	unsigned long arg;
 	char *endarg;
-	char msr_file_name[64];
 
 	program = argv[0];
 
@@ -71,6 +97,9 @@ int main(int argc, char *argv[])
 			fprintf(stderr, "%s: version %s\n", program,
 				VERSION_STRING);
 			exit(0);
+		case 'a':
+			cpu = -1;
+			break;
 		case 'p':
 			arg = strtoul(optarg, &endarg, 0);
 			if (*endarg || arg > 255) {
@@ -93,6 +122,21 @@ int main(int argc, char *argv[])
 
 	reg = strtoul(argv[optind++], NULL, 0);
 
+	if (cpu == -1) {
+		wrmsr_on_all_cpus(reg, argc - optind, &argv[optind]);
+	} else {
+		wrmsr_on_cpu(reg, cpu, argc - optind, &argv[optind]);
+	}
+
+	exit(0);
+}
+
+void wrmsr_on_cpu(uint32_t reg, int cpu, int valcnt, char *regvals[])
+{
+	uint64_t data;
+	int fd;
+	char msr_file_name[64];
+
 	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
 	fd = open(msr_file_name, O_WRONLY);
 	if (fd < 0) {
@@ -109,8 +153,8 @@ int main(int argc, char *argv[])
 		}
 	}
 
-	while (optind < argc) {
-		data = strtoull(argv[optind++], NULL, 0);
+	while (valcnt--) {
+		data = strtoull(*regvals++, NULL, 0);
 		if (pwrite(fd, &data, sizeof data, reg) != sizeof data) {
 			if (errno == EIO) {
 				fprintf(stderr,
@@ -127,5 +171,5 @@ int main(int argc, char *argv[])
 
 	close(fd);
 
-	exit(0);
+	return;
 }