From 73884e62ce6f013a48769fadd3512b33b347bb77 Mon Sep 17 00:00:00 2001
From: Michal Berger <michalx.berger@intel.com>
Date: Tue, 29 Dec 2020 11:56:37 +0100
Subject: [PATCH] test/scheduler: Add simple tool for utilizing msr driver

This tool simply returns contents of EAX|ECX registers for a specific
MSR. Targeted use is to compare DPDK's governor results while working
under intel_pstate driver.

Change-Id: I40b3f3601d41e45ba65c96b99ebd1b6949b5af20
Signed-off-by: Michal Berger <michalx.berger@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/5737
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Maciej Szwed <maciej.szwed@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Karol Latecki <karol.latecki@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
---
 test/scheduler/rdmsr.pl | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100755 test/scheduler/rdmsr.pl

diff --git a/test/scheduler/rdmsr.pl b/test/scheduler/rdmsr.pl
new file mode 100755
index 000000000..b4628116a
--- /dev/null
+++ b/test/scheduler/rdmsr.pl
@@ -0,0 +1,34 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+use constant SEEK_CUR => 1;
+
+( @ARGV == 2 ) || exit(1);
+
+my $cpu_path = sprintf( "/dev/cpu/%u/msr", shift() );
+my $msr      = hex( shift() );
+my $reg_size = 8;
+my ( @msr, $msr_buf, $reg );
+
+unless ( -e $cpu_path ) {
+    printf STDERR "$cpu_path doesn't exist\n";
+    exit(1);
+}
+
+open( MSR, "<", $cpu_path );
+sysseek( MSR, $msr, SEEK_CUR );
+sysread( MSR, $msr_buf, $reg_size );
+@msr = unpack( "C*", $msr_buf );
+
+unless ( @msr == $reg_size ) {
+    printf STDERR "Failed to read $cpu_path\n";
+    exit(1);
+}
+
+for ( my $byte = @msr - 1 ; $byte >= 0 ; $byte-- ) {
+    $reg |= $msr[$byte] << ( $byte * 8 );
+}
+
+printf( "0x%x\n", $reg );