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/* $Id: VBoxCpuReportMsrLinux.cpp $ */
/** @file
* MsrLinux - Linux-specific MSR access.
*/
/*
* Copyright (C) 2013-2022 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* SPDX-License-Identifier: GPL-3.0-only
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include "VBoxCpuReport.h"
#include <iprt/err.h>
#include <iprt/file.h>
#include <iprt/thread.h>
#ifndef RT_OS_WINDOWS
# include <unistd.h>
#else /* RT_OS_WINDOWS: for test compiling this file on windows */
# include <io.h>
int pread(int, void *, size_t, off_t);
int pwrite(int, void const *, size_t, off_t);
#endif
#include <fcntl.h>
#include <errno.h>
/*********************************************************************************************************************************
* Defined Constants And Macros *
*********************************************************************************************************************************/
#define MSR_DEV_NAME "/dev/cpu/0/msr"
/*********************************************************************************************************************************
* Global Variables *
*********************************************************************************************************************************/
/** The /dev/xxx/msr file descriptor. */
static int g_fdMsr;
/**
* @interface_method_impl{VBCPUREPMSRACCESSORS,pfnMsrProberRead}
*/
static DECLCALLBACK(int) linuxMsrProberRead(uint32_t uMsr, RTCPUID idCpu, uint64_t *puValue, bool *pfGp)
{
int rc = VINF_SUCCESS;
if (idCpu != NIL_RTCPUID)
return VERR_INVALID_PARAMETER;
if (g_fdMsr < 0)
return VERR_INVALID_STATE;
*pfGp = true;
if (pread(g_fdMsr, puValue, sizeof(*puValue), uMsr) != sizeof(*puValue))
rc = VERR_READ_ERROR;
else
*pfGp = false;
return RT_SUCCESS(rc) && !pfGp;
}
/**
* @interface_method_impl{VBCPUREPMSRACCESSORS,pfnMsrProberWrite}
*/
static DECLCALLBACK(int) linuxMsrProberWrite(uint32_t uMsr, RTCPUID idCpu, uint64_t uValue, bool *pfGp)
{
int rc = VINF_SUCCESS;
if (idCpu != NIL_RTCPUID)
return VERR_INVALID_PARAMETER;
if (g_fdMsr < 0)
return VERR_INVALID_STATE;
*pfGp = true;
if (pwrite(g_fdMsr, &uValue, sizeof(uValue), uMsr) != sizeof(uValue))
rc = VERR_WRITE_ERROR;
else
*pfGp = false;
return RT_SUCCESS(rc) && !pfGp;
}
/**
* @interface_method_impl{VBCPUREPMSRACCESSORS,pfnMsrProberModify}
*/
static DECLCALLBACK(int) linuxMsrProberModify(uint32_t uMsr, RTCPUID idCpu, uint64_t fAndMask, uint64_t fOrMask,
PSUPMSRPROBERMODIFYRESULT pResult)
{
int rc = VINF_SUCCESS;
uint64_t uBefore, uWrite, uAfter;
int rcBefore, rcWrite, rcAfter, rcRestore;
if (idCpu != NIL_RTCPUID)
return VERR_INVALID_PARAMETER;
if (g_fdMsr < 0)
return VERR_INVALID_STATE;
#if 0
vbCpuRepDebug("MSR %#x\n", uMsr);
RTThreadSleep(10);
#endif
rcBefore = pread(g_fdMsr, &uBefore, sizeof(uBefore), uMsr);
uWrite = (uBefore & fAndMask) | fOrMask;
rcWrite = pwrite(g_fdMsr, &uWrite, sizeof(uWrite), uMsr);
rcAfter = pread(g_fdMsr, &uAfter, sizeof(uAfter), uMsr);
rcRestore = pwrite(g_fdMsr, &uBefore, sizeof(uBefore), uMsr);
#if 0
vbCpuRepDebug("MSR: %#x, %#llx -> %#llx -> %#llx (%d/%d/%d/%d)\n",
uMsr, uBefore, uWrite, uAfter,
rcBefore, rcWrite != sizeof(uWrite), rcAfter, rcRestore);
#endif
pResult->uBefore = uBefore;
pResult->uWritten = uWrite;
pResult->uAfter = uAfter;
pResult->fBeforeGp = rcBefore != sizeof(uBefore);
pResult->fModifyGp = rcWrite != sizeof(uWrite);
pResult->fAfterGp = rcAfter != sizeof(uAfter);
pResult->fRestoreGp = rcRestore != sizeof(uBefore);
return rc;
}
/**
* @interface_method_impl{VBCPUREPMSRACCESSORS,pfnTerm}
*/
static DECLCALLBACK(void) linuxMsrProberTerm(void)
{
if (g_fdMsr >= 0)
{
close(g_fdMsr);
g_fdMsr = -1;
}
}
int VbCpuRepMsrProberInitPlatform(PVBCPUREPMSRACCESSORS pMsrAccessors)
{
RTFILE hFile;
int rc = RTFileOpen(&hFile, MSR_DEV_NAME, RTFILE_O_READWRITE | RTFILE_O_DENY_NONE | RTFILE_O_OPEN);
if (RT_SUCCESS(rc))
{
g_fdMsr = RTFileToNative(hFile);
Assert(g_fdMsr != -1);
pMsrAccessors->fAtomic = false; /* Can't modify/restore MSRs without trip to R3. */
pMsrAccessors->pfnMsrProberRead = linuxMsrProberRead;
pMsrAccessors->pfnMsrProberWrite = linuxMsrProberWrite;
pMsrAccessors->pfnMsrProberModify = linuxMsrProberModify;
pMsrAccessors->pfnTerm = linuxMsrProberTerm;
return VINF_SUCCESS;
}
vbCpuRepDebug("warning: Failed to open " MSR_DEV_NAME ": %Rrc\n", rc);
return rc;
}
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