1 | /* $Id: VBoxCpuReportMsrLinux.cpp 106061 2024-09-16 14:03:52Z vboxsync $ */
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2 | /** @file
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3 | * MsrLinux - Linux-specific MSR access.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2013-2024 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * SPDX-License-Identifier: GPL-3.0-only
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26 | */
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27 |
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28 |
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29 | /*********************************************************************************************************************************
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30 | * Header Files *
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31 | *********************************************************************************************************************************/
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32 | #include "VBoxCpuReport.h"
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33 |
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34 | #include <iprt/err.h>
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35 | #include <iprt/file.h>
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36 | #include <iprt/thread.h>
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37 |
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38 | #ifndef RT_OS_WINDOWS
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39 | # include <unistd.h>
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40 | #else /* RT_OS_WINDOWS: for test compiling this file on windows */
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41 | # include <io.h>
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42 | int pread(int, void *, size_t, off_t);
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43 | int pwrite(int, void const *, size_t, off_t);
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44 | #endif
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45 | #include <fcntl.h>
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46 | #include <errno.h>
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47 |
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48 |
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49 | /*********************************************************************************************************************************
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50 | * Defined Constants And Macros *
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51 | *********************************************************************************************************************************/
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52 | #define MSR_DEV_NAME "/dev/cpu/0/msr"
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53 |
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54 |
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55 | /*********************************************************************************************************************************
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56 | * Global Variables *
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57 | *********************************************************************************************************************************/
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58 | /** The /dev/xxx/msr file descriptor. */
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59 | static int g_fdMsr;
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60 |
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61 |
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62 | /**
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63 | * @interface_method_impl{VBCPUREPMSRACCESSORS,pfnMsrProberRead}
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64 | */
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65 | static DECLCALLBACK(int) linuxMsrProberRead(uint32_t uMsr, RTCPUID idCpu, uint64_t *puValue, bool *pfGp)
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66 | {
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67 | int rc = VINF_SUCCESS;
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68 |
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69 | if (idCpu != NIL_RTCPUID)
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70 | return VERR_INVALID_PARAMETER;
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71 |
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72 | if (g_fdMsr < 0)
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73 | return VERR_INVALID_STATE;
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74 |
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75 | *pfGp = true;
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76 | if (pread(g_fdMsr, puValue, sizeof(*puValue), uMsr) != sizeof(*puValue))
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77 | rc = VERR_READ_ERROR;
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78 | else
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79 | *pfGp = false;
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80 |
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81 | return RT_SUCCESS(rc) && !pfGp;
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82 | }
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83 |
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84 |
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85 | /**
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86 | * @interface_method_impl{VBCPUREPMSRACCESSORS,pfnMsrProberWrite}
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87 | */
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88 | static DECLCALLBACK(int) linuxMsrProberWrite(uint32_t uMsr, RTCPUID idCpu, uint64_t uValue, bool *pfGp)
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89 | {
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90 | int rc = VINF_SUCCESS;
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91 |
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92 | if (idCpu != NIL_RTCPUID)
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93 | return VERR_INVALID_PARAMETER;
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94 |
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95 | if (g_fdMsr < 0)
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96 | return VERR_INVALID_STATE;
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97 |
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98 | *pfGp = true;
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99 | if (pwrite(g_fdMsr, &uValue, sizeof(uValue), uMsr) != sizeof(uValue))
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100 | rc = VERR_WRITE_ERROR;
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101 | else
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102 | *pfGp = false;
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103 |
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104 | return RT_SUCCESS(rc) && !pfGp;
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105 | }
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106 |
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107 | /**
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108 | * @interface_method_impl{VBCPUREPMSRACCESSORS,pfnMsrProberModify}
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109 | */
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110 | static DECLCALLBACK(int) linuxMsrProberModify(uint32_t uMsr, RTCPUID idCpu, uint64_t fAndMask, uint64_t fOrMask,
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111 | PSUPMSRPROBERMODIFYRESULT pResult)
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112 | {
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113 | int rc = VINF_SUCCESS;
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114 | uint64_t uBefore, uWrite, uAfter;
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115 | int rcBefore, rcWrite, rcAfter, rcRestore;
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116 |
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117 | if (idCpu != NIL_RTCPUID)
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118 | return VERR_INVALID_PARAMETER;
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119 |
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120 | if (g_fdMsr < 0)
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121 | return VERR_INVALID_STATE;
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122 |
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123 | #if 0
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124 | vbCpuRepDebug("MSR %#x\n", uMsr);
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125 | RTThreadSleep(10);
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126 | #endif
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127 | rcBefore = pread(g_fdMsr, &uBefore, sizeof(uBefore), uMsr);
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128 | uWrite = (uBefore & fAndMask) | fOrMask;
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129 | rcWrite = pwrite(g_fdMsr, &uWrite, sizeof(uWrite), uMsr);
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130 | rcAfter = pread(g_fdMsr, &uAfter, sizeof(uAfter), uMsr);
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131 | rcRestore = pwrite(g_fdMsr, &uBefore, sizeof(uBefore), uMsr);
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132 |
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133 | #if 0
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134 | vbCpuRepDebug("MSR: %#x, %#llx -> %#llx -> %#llx (%d/%d/%d/%d)\n",
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135 | uMsr, uBefore, uWrite, uAfter,
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136 | rcBefore, rcWrite != sizeof(uWrite), rcAfter, rcRestore);
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137 | #endif
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138 | pResult->uBefore = uBefore;
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139 | pResult->uWritten = uWrite;
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140 | pResult->uAfter = uAfter;
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141 | pResult->fBeforeGp = rcBefore != sizeof(uBefore);
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142 | pResult->fModifyGp = rcWrite != sizeof(uWrite);
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143 | pResult->fAfterGp = rcAfter != sizeof(uAfter);
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144 | pResult->fRestoreGp = rcRestore != sizeof(uBefore);
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145 |
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146 | return rc;
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147 | }
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148 |
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149 |
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150 | /**
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151 | * @interface_method_impl{VBCPUREPMSRACCESSORS,pfnTerm}
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152 | */
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153 | static DECLCALLBACK(void) linuxMsrProberTerm(void)
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154 | {
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155 | if (g_fdMsr >= 0)
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156 | {
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157 | close(g_fdMsr);
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158 | g_fdMsr = -1;
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159 | }
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160 | }
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161 |
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162 | int VbCpuRepMsrProberInitPlatform(PVBCPUREPMSRACCESSORS pMsrAccessors)
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163 | {
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164 | RTFILE hFile;
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165 | int rc = RTFileOpen(&hFile, MSR_DEV_NAME, RTFILE_O_READWRITE | RTFILE_O_DENY_NONE | RTFILE_O_OPEN);
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166 | if (RT_SUCCESS(rc))
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167 | {
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168 | g_fdMsr = RTFileToNative(hFile);
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169 | Assert(g_fdMsr != -1);
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170 |
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171 | pMsrAccessors->fAtomic = false; /* Can't modify/restore MSRs without trip to R3. */
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172 | pMsrAccessors->pfnMsrProberRead = linuxMsrProberRead;
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173 | pMsrAccessors->pfnMsrProberWrite = linuxMsrProberWrite;
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174 | pMsrAccessors->pfnMsrProberModify = linuxMsrProberModify;
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175 | pMsrAccessors->pfnTerm = linuxMsrProberTerm;
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176 | return VINF_SUCCESS;
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177 | }
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178 | vbCpuRepDebug("warning: Failed to open " MSR_DEV_NAME ": %Rrc\n", rc);
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179 | return rc;
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180 | }
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