Hi all,
> >
> > I have detected the following issue:
> > I use an x86 PC using kernel 3.2.34-rt51 and I want to run VirtualBox 4.2.4 using
> this PC as host.
>
> > However, the PC freezes completely when loading the vbox driver "vboxdrv".
> > Using the very same kernel without the RT_PREEMPT patch shows no issues.
> >
> > Using an older version of VirtualBox (V4.1.22) works fine as well.
> >
> > I know that this might be slightly off-topic. However there might be some
> RT_PREEMPT users that have detected the same issue and know a solution for this.
> >
> > I have attached my kernel .config file.
> >
> > Thanks for any feedback on this.
>
> Try enabling lock debugging. Likely there is an incompatibility in the
> vbox driver or even a bug, and that may reveal more details.
>
> Otherwise: KVM is the better choice on Linux hosts, and it works fine
> over -rt.
I am about to try this out in parallel. It looks promising...
In addition, I did a long debug session (using a parallel port LED adapter any many PC resets...) to identify the issue.
Lock debugging did not work as really everything was frozen or the PC.
However, I finally identified the critical lines of code.
The relevant source file is the attached file "spinlock-r0drv-linux.c" of the VirtualBox OSE V4.2.4.
The freeze happens in line 158 (spin_unlock_irqrestore()).
----------- BEGIN CODE FRAGMENT --------------------
RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
{
PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE_VARS();
AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC,
("pThis=%p u32Magic=%08x\n", pThis, pThis ? (int)pThis->u32Magic : 0));
RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE(pThis);
if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
{
unsigned long fIntSaved = pThis->fIntSaved;
pThis->fIntSaved = 0;
spin_unlock_irqrestore(&pThis->Spinlock, fIntSaved); // <--- Here is the freeze!
}
else
spin_unlock(&pThis->Spinlock);
RT_ASSERT_PREEMPT_CPUID();
}
RT_EXPORT_SYMBOL(RTSpinlockRelease);
----------- END CODE FRAGMENT --------------------
It has something to do with the spin locks used in VirtualBox.
Likely it does not consider the RT_PREEMPT use case here...
Is there a way to make the spin lock calls compatible to the RT_PREEMPT patch?
Any ideas for solving this issue are highly welcome!
Thanks a lot.
Best regards.
Mathias
/* $Id: spinlock-r0drv-linux.c $ */
/** @file
* IPRT - Spinlocks, Ring-0 Driver, Linux.
*/
/*
* Copyright (C) 2006-2010 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*/
/*******************************************************************************
* Header Files *
*******************************************************************************/
#include "the-linux-kernel.h"
#include "internal/iprt.h"
#include <iprt/spinlock.h>
#include <iprt/asm.h>
#if defined(RT_ARCH_AMD64) || defined(RT_ARCH_X86)
# include <iprt/asm-amd64-x86.h>
#endif
#include <iprt/assert.h>
#include <iprt/err.h>
#include <iprt/mem.h>
#include <iprt/mp.h>
#include <iprt/thread.h>
#include "internal/magics.h"
/*******************************************************************************
* Structures and Typedefs *
*******************************************************************************/
/**
* Wrapper for the spinlock_t structure.
*/
typedef struct RTSPINLOCKINTERNAL
{
/** Spinlock magic value (RTSPINLOCK_MAGIC). */
uint32_t volatile u32Magic;
/** The spinlock creation flags. */
uint32_t fFlags;
/** The saved interrupt flag. */
unsigned long volatile fIntSaved;
/** The linux spinlock structure. */
spinlock_t Spinlock;
#ifdef RT_MORE_STRICT
/** The idAssertCpu variable before acquring the lock for asserting after
* releasing the spinlock. */
RTCPUID volatile idAssertCpu;
/** The CPU that owns the lock. */
RTCPUID volatile idCpuOwner;
#endif
} RTSPINLOCKINTERNAL, *PRTSPINLOCKINTERNAL;
RTDECL(int) RTSpinlockCreate(PRTSPINLOCK pSpinlock, uint32_t fFlags, const char *pszName)
{
PRTSPINLOCKINTERNAL pThis;
AssertReturn(fFlags == RTSPINLOCK_FLAGS_INTERRUPT_SAFE || fFlags == RTSPINLOCK_FLAGS_INTERRUPT_UNSAFE, VERR_INVALID_PARAMETER);
/*
* Allocate.
*/
Assert(sizeof(RTSPINLOCKINTERNAL) > sizeof(void *));
pThis = (PRTSPINLOCKINTERNAL)RTMemAlloc(sizeof(*pThis));
if (!pThis)
return VERR_NO_MEMORY;
/*
* Initialize and return.
*/
pThis->u32Magic = RTSPINLOCK_MAGIC;
pThis->fFlags = fFlags;
pThis->fIntSaved = 0;
#ifdef RT_MORE_STRICT
pThis->idCpuOwner = NIL_RTCPUID;
pThis->idAssertCpu = NIL_RTCPUID;
#endif
spin_lock_init(&pThis->Spinlock);
*pSpinlock = pThis;
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTSpinlockCreate);
RTDECL(int) RTSpinlockDestroy(RTSPINLOCK Spinlock)
{
/*
* Validate input.
*/
PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
if (!pThis)
return VERR_INVALID_PARAMETER;
if (pThis->u32Magic != RTSPINLOCK_MAGIC)
{
AssertMsgFailed(("Invalid spinlock %p magic=%#x\n", pThis, pThis->u32Magic));
return VERR_INVALID_PARAMETER;
}
ASMAtomicIncU32(&pThis->u32Magic);
RTMemFree(pThis);
return VINF_SUCCESS;
}
RT_EXPORT_SYMBOL(RTSpinlockDestroy);
RTDECL(void) RTSpinlockAcquire(RTSPINLOCK Spinlock)
{
PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
RT_ASSERT_PREEMPT_CPUID_VAR();
AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC,
("pThis=%p u32Magic=%08x\n", pThis, pThis ? (int)pThis->u32Magic : 0));
if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
{
unsigned long fIntSaved;
spin_lock_irqsave(&pThis->Spinlock, fIntSaved);
pThis->fIntSaved = fIntSaved;
}
else
spin_lock(&pThis->Spinlock);
RT_ASSERT_PREEMPT_CPUID_SPIN_ACQUIRED(pThis);
}
RT_EXPORT_SYMBOL(RTSpinlockAcquire);
RTDECL(void) RTSpinlockRelease(RTSPINLOCK Spinlock)
{
PRTSPINLOCKINTERNAL pThis = (PRTSPINLOCKINTERNAL)Spinlock;
RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE_VARS();
AssertMsg(pThis && pThis->u32Magic == RTSPINLOCK_MAGIC,
("pThis=%p u32Magic=%08x\n", pThis, pThis ? (int)pThis->u32Magic : 0));
RT_ASSERT_PREEMPT_CPUID_SPIN_RELEASE(pThis);
if (pThis->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)
{
unsigned long fIntSaved = pThis->fIntSaved;
pThis->fIntSaved = 0;
spin_unlock_irqrestore(&pThis->Spinlock, fIntSaved);
}
else
spin_unlock(&pThis->Spinlock);
RT_ASSERT_PREEMPT_CPUID();
}
RT_EXPORT_SYMBOL(RTSpinlockRelease);
RTDECL(void) RTSpinlockReleaseNoInts(RTSPINLOCK Spinlock)
{
#if 1
if (RT_UNLIKELY(!(Spinlock->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE)))
RTAssertMsg2("RTSpinlockReleaseNoInts: %p (magic=%#x)\n", Spinlock, Spinlock->u32Magic);
#else
AssertRelease(Spinlock->fFlags & RTSPINLOCK_FLAGS_INTERRUPT_SAFE);
#endif
RTSpinlockRelease(Spinlock);
}
RT_EXPORT_SYMBOL(RTSpinlockReleaseNoInts);
