From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frank van der Linden <Frank.Vanderlinden@Sun.COM>
Subject: Re: Re: BSOD
	"A clock interrupt was not recevied	onasecondary processor within the
	allocated time interval"
Date: Wed, 07 Jan 2009 10:42:08 -0700
Message-ID: <4964E970.3090803@Sun.COM>
References: <49627C6B.7000900@virtualiron.com>
	<C5883149.20C37%keir.fraser@eu.citrix.com>
	<20090106103909.GA23206@weybridge.uk.xensource.com>
Mime-Version: 1.0
Content-Type: text/plain; format=flowed; charset=windows-1252
Content-Transfer-Encoding: quoted-printable
Return-path: <xen-devel-bounces@lists.xensource.com>
In-reply-to: <20090106103909.GA23206@weybridge.uk.xensource.com>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: Steven Smith <steven.smith@eu.citrix.com>
Cc: "Xen-Devel (E-mail)" <xen-devel@lists.xensource.com>, Steve Prochniak <sprochniak@virtualiron.com>, Andrew Lyon <andrew.lyon@gmail.com>, Keir Fraser <keir.fraser@eu.citrix.com>, xen-users@lists.xensource.com, Ben Guthro <bguthro@virtualiron.com>
List-Id: xen-devel@lists.xenproject.org

Steven Smith wrote:
>> Alternative Viridian interface support was checked in. When enabled, i=
t
>> ought to be sufficient to disable these bugchecks. =8Cviridian=3D1=B9 =
needs to be
>> specified in the domain config file.
> Hmm...  In order for the Viridian stuff to actually solve this
> problem, you need to set the relaxed-timers bit.  It doesn't look like
> the xen-unstable implementation does so.  Something like this might
> help:
>=20
> diff -r f6b92526e916 xen/arch/x86/hvm/viridian.c
> --- a/xen/arch/x86/hvm/viridian.c	Tue Jan 06 09:14:39 2009 +0000
> +++ b/xen/arch/x86/hvm/viridian.c	Tue Jan 06 10:32:26 2009 +0000
> @@ -37,6 +37,7 @@
> =20
>  /* Viridian CPUID 4000004, Implementation Recommendations. */
>  #define CPUID4A_MSR_BASED_APIC  (1 << 3)
> +#define CPUID4A_RELAX_TIMER_INT_HANDLING (1 << 5)
> =20
>  int cpuid_viridian_leaves(unsigned int leaf, unsigned int *eax,
>                            unsigned int *ebx, unsigned int *ecx,
> @@ -84,7 +85,7 @@
>          if ( (d->arch.hvm_domain.viridian.guest_os_id.raw =3D=3D 0) ||
>               (d->arch.hvm_domain.viridian.guest_os_id.fields.os < 4) )
>              break;
> -        *eax =3D CPUID4A_MSR_BASED_APIC;
> +        *eax =3D CPUID4A_MSR_BASED_APIC | CPUID4A_RELAX_TIMER_INT_HAND=
LING;
>          *ebx =3D 2047; /* long spin count */
>          break;
>      }
>=20
> But note that I haven't tested this *at all*.

That appears to work. I have a test setup where I can introduce an=20
arbitrary delay in qemu-dm. It's easy to trigger bug check 0x101 in=20
Windows 2008 that way. Using viridian=3D1, with the relaxed timer bit set=
,=20
I have been unable to crash Windows 2008.

Looks like a good thing to commit.

- Frank