From f2502a1201e95171265dfd707d3869e5f30ad01e Mon Sep 17 00:00:00 2001
From: Kanoj Sarcar <kanoj@google.com>
Date: Fri, 11 Mar 2016 14:50:59 -0800
Subject: [PATCH] Fix -a option for rdmsr/wrmsr. Current Linux creates /dev/cpu
 files for non existant CPU's that trips up the "all" handling on the first
 encountered error.

---
 rdmsr.c | 9 ++++++++-
 wrmsr.c | 4 ++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/rdmsr.c b/rdmsr.c
index d3e3c22..d1acca5 100644
--- a/rdmsr.c
+++ b/rdmsr.c
@@ -50,6 +50,7 @@ static const struct option long_options[] = {
 	{0, 0, 0, 0}
 };
 static const char short_options[] = "hVxXdoruc0ap:f:";
+static int doing_for_all = 0;
 
 /* Number of decimal digits for a certain number of bits */
 /* (int) ceil(log(2^n)/log(10)) */
@@ -196,6 +197,7 @@ int main(int argc, char *argv[])
 	reg = strtoul(argv[optind], NULL, 0);
 
 	if (cpu == -1) {
+		doing_for_all = 1;
 		rdmsr_on_all_cpus(reg);
 	}
 	else
@@ -216,6 +218,8 @@ void rdmsr_on_cpu(uint32_t reg, int cpu)
 	fd = open(msr_file_name, O_RDONLY);
 	if (fd < 0) {
 		if (errno == ENXIO) {
+			if (doing_for_all)
+				return;
 			fprintf(stderr, "rdmsr: No CPU %d\n", cpu);
 			exit(2);
 		} else if (errno == EIO) {
@@ -350,7 +354,10 @@ void rdmsr_on_cpu(uint32_t reg, int cpu)
 	if (width < 1)
 		width = 1;
 
-	if (pat)
+	if (pat) {
+		if (doing_for_all)
+			printf("CPU %d: ", cpu);
 		printf(pat, width, data);
+	}
 	return;
 }
diff --git a/wrmsr.c b/wrmsr.c
index 8a601b9..af16a8d 100644
--- a/wrmsr.c
+++ b/wrmsr.c
@@ -39,6 +39,7 @@ static const struct option long_options[] = {
 	{0, 0, 0, 0}
 };
 static const char short_options[] = "hVap:";
+static int doing_for_all = 0;
 
 const char *program;
 
@@ -123,6 +124,7 @@ int main(int argc, char *argv[])
 	reg = strtoul(argv[optind++], NULL, 0);
 
 	if (cpu == -1) {
+		doing_for_all = 1;
 		wrmsr_on_all_cpus(reg, argc - optind, &argv[optind]);
 	} else {
 		wrmsr_on_cpu(reg, cpu, argc - optind, &argv[optind]);
@@ -141,6 +143,8 @@ void wrmsr_on_cpu(uint32_t reg, int cpu, int valcnt, char *regvals[])
 	fd = open(msr_file_name, O_WRONLY);
 	if (fd < 0) {
 		if (errno == ENXIO) {
+			if (doing_for_all)
+				return;
 			fprintf(stderr, "wrmsr: No CPU %d\n", cpu);
 			exit(2);
 		} else if (errno == EIO) {