msr

Documentation

Overview

This file contains support functions for msr access for Linux.

Index

• Variables
• func Locked() error
• type CPUs
  • func AllCPUs() (CPUs, error)
  • func GlobCPUs(g string) (CPUs, []error)
  • func (c CPUs) String() string
• type MSR
  • func (m MSR) Read(c CPUs) ([]uint64, []error)
  • func (m MSR) String() string
  • func (m MSR) Test(c CPUs, clearMask uint64, setMask uint64) []error
  • func (m MSR) TestAndSet(c CPUs, clearMask uint64, setMask uint64) []error
  • func (m MSR) Write(c CPUs, data ...uint64) []error
• type MSRVal
  • func (m MSRVal) String() string

Variables

var Debug = func(string, ...interface{}) {}

Debug can be set for debug prints on MSR operaitons. It can be set to, e.g., log.Printf. It's default action is to do nothing.

var LockIntel = []MSRVal{
	{

		Addr: IntelIA32FeatureControl,
		Name: "IntelIA32FeatureControl",
		Set:  1 << 0,
	},
	{

		Addr: IntelPkgCstConfigControl,
		Name: "IntelPkgCstConfigControl",
		Set:  1 << 15,
	},
	{

		Addr: IntelFeatureConfig,
		Name: "IntelFeatureConfig",
		Set:  1 << 0,
	},
	{

		Addr: IntelDramPowerLimit,
		Name: "IntelDramPowerLimit",
		Set:  1 << 31,
	},
	{

		Addr: IntelConfigTDPControl,
		Name: "IntelConfigTDPControl",
		Set:  1 << 31,
	},
	{

		Addr: IntelIA32DebugInterface,
		Name: "IntelIA32DebugInterface",
		Set:  1 << 30,
	},
}

Functions

func Locked

func Locked() error

Locked verifies that for all MSRVal's for the CPU vendor, the MSRs are locked. TODO: this is another Intel-specific function at present.

Types

type CPUs

type CPUs []uint64

CPUs is a slice of the various cpus to read or write the MSR to.

func AllCPUs

func AllCPUs() (CPUs, error)

AllCPUs searches for actual present CPUs instead of relying on the glob. This is more accurate than what's presented in /dev/cpu/*/msr

func GlobCPUs

func GlobCPUs(g string) (CPUs, []error)

GlobCPUs allow the user to specify CPUs using a glob as one would in /dev/cpu

func (CPUs) String

func (c CPUs) String() string

String pretty prints the list of CPUs. For example: 1-2,4

type MSR

type MSR uint32

MSR defines an MSR address.

const (
	// This is Intel's name. It makes no sense: this register is present
	// in 64-bit CPUs.
	IntelIA32FeatureControl  MSR = 0x3A  // MSR_IA32_FEATURE_CONTROL
	IntelPkgCstConfigControl MSR = 0xE2  // MSR_PKG_CST_CONFIG_CONTROL
	IntelFeatureConfig       MSR = 0x13c // MSR_FEATURE_CONFIG
	IntelDramPowerLimit      MSR = 0x618 // MSR_DRAM_POWER_LIMIT
	IntelConfigTDPControl    MSR = 0x64B // MSR_CONFIG_TDP_CONTROL
	IntelIA32DebugInterface  MSR = 0xC80 // IA32_DEBUG_INTERFACE
)

func (MSR) Read

func (m MSR) Read(c CPUs) ([]uint64, []error)

Read reads an MSR from a set of CPUs.

func (MSR) String

func (m MSR) String() string

String implements String() for MSR.

func (MSR) Test

func (m MSR) Test(c CPUs, clearMask uint64, setMask uint64) []error

Test takes a mask of bits to clear and to set, and returns an error for those that do not match.

func (MSR) TestAndSet

func (m MSR) TestAndSet(c CPUs, clearMask uint64, setMask uint64) []error

TestAndSet takes a mask of bits to clear and to set, and applies them to the specified MSR in each of the CPUs. Note that TestAndSet does not write if the mask does not change the MSR.

func (MSR) Write

func (m MSR) Write(c CPUs, data ...uint64) []error

Write writes values to an MSR on a set of CPUs. The data must be passed as a scalar (single value) or a slice. If the data slice has more than one element, the length of the data slice and the CPU slice must be the same. If a single value is given, it will be written to all the CPUs. If multiple data values are given, each will be written to its corresponding CPU.

type MSRVal

type MSRVal struct {
	// Addr is the address of the MSR.
	Addr MSR
	// Name is a printable name.
	Name string
	// Clear are bits to clear in TestAndSet and Test.
	Clear uint64
	// Set are bits to set in TestAndSet and Test; or the value to write
	// if the MSR is writeonly.
	Set uint64
	// WriteOnly indicats an MSR is writeonly.
	WriteOnly bool
}

MSRVal defines an MSR Value to be used in TestAndSet, Test, and other operations.

func (MSRVal) String

func (m MSRVal) String() string

String implements String() for MSRVal