VirtualBox 4.2.4 freezes PC using RT_PREEMPT kernel

VirtualBox 4.2.4 freezes PC using RT_PREEMPT kernel

[Koehrer Mathias (ETAS/ESS2)]

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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.

Regards

Mathias



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Re: VirtualBox 4.2.4 freezes PC using RT_PREEMPT kernel

[Jan Kiszka]

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On 2012-12-14 09:58, Koehrer Mathias (ETAS/ESS2) wrote:
> 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.

Jan



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Re: VirtualBox 4.2.4 freezes PC using RT_PREEMPT kernel

[Thomas Gleixner]

On Wed, 19 Dec 2012, Koehrer Mathias (ETAS/ESS2) wrote:
> > >
> > > 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 --------------------

Was it really necessary to expose us to the camel case inflicted
horror of the VirtualBox spinlock abstraction layer just a few days
before Christmas?

> It has something to do with the spin locks used in VirtualBox.

Why am I not surprised?

> Likely it does not consider the RT_PREEMPT use case here...

I don't think so. That's a genuine problem unrelated to RT.

> Is there a way to make the spin lock calls compatible to the RT_PREEMPT patch?

No. The API usage seems to be correct, but RT might expose an
otherwise hard to trigger live time issue, data corruption or whatever
problem.

You said:
> Lock debugging did not work as really everything was frozen or the PC.

That's an indicator that something is really wrong. Can you just run
the same crap on a non-rt kernel with CONFIG_PROVE_LOCKING enabled ?

Thanks,

	tglx

Re: VirtualBox 4.2.4 freezes PC using RT_PREEMPT kernel

[Koehrer Mathias (ETAS/ESS2)]

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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


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/* $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);