github.com/intel/goresctrl@v0.5.0/pkg/utils/msr.go (about)

     1  /*
     2  Copyright 2021 Intel Corporation
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package utils
    18  
    19  import (
    20  	"encoding/binary"
    21  	"fmt"
    22  	"os"
    23  
    24  	goresctrlpath "github.com/intel/goresctrl/pkg/path"
    25  )
    26  
    27  func ReadMSR(cpu ID, msr int64) (uint64, error) {
    28  	path := goresctrlpath.Path("dev/cpu", fmt.Sprintf("%d", cpu), "msr")
    29  	file, err := os.Open(path)
    30  	if err != nil {
    31  		return 0, err
    32  	}
    33  
    34  	defer file.Close()
    35  
    36  	// Whence is the point of reference for offset
    37  	// 0 = Beginning of file
    38  	// 1 = Current position
    39  	// 2 = End of file
    40  	var whence int = 0
    41  	_, err = file.Seek(msr, whence)
    42  	if err != nil {
    43  		return 0, err
    44  	}
    45  
    46  	data := make([]byte, 8)
    47  
    48  	_, err = file.Read(data)
    49  	if err != nil {
    50  		return 0, err
    51  	}
    52  
    53  	return binary.LittleEndian.Uint64(data), nil
    54  }