linux-kernel - RE: BUG: 2.6.30.1 pv_ops kernel boot failure

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Date:	Tue, 25 Aug 2009 14:06:32 +0100
From:	"James Dingwall" <james.dingwall@...ocs.com>
To:	"Andreas Herrmann" <andreas.herrmann3@....com>
Cc:	<linux-kernel@...r.kernel.org>
Subject: RE: BUG: 2.6.30.1 pv_ops kernel boot failure - bisected


> > On Tue, Aug 25, 2009 at 12:04:54PM +0100, James Dingwall wrote:
> > >
> > > Hi,
> > >
> > > I have encountered what appears to be a bug when using the 2.6.30
> > stable
> > > series as a pv_ops kernel under Xen 3.4.1.  The problem appears to
> > have
> > > been introduced with the following commit (provided I bisected it
> > > correctly)
> > >
> > > commit bb9b409349f533a919b6b6d95698fbe6ff4aa209
> > > Author: Andreas Herrmann <andreas.herrmann3@....com>
> > > Date:   Mon Jun 8 15:55:09 2009 +0200
> > >
> > >     x86: Detect use of extended APIC ID for AMD CPUs
> > >
> > > When I try and boot the domU (xm create -c) I do not get any
> output.
> > > With this commit reverted I can boot 2.6.30.5 pv_ops without
issue,
> > > output follows below.  The system is a dual Opteron 242.  If more
> > > details about the hardware or configuration are required to debug
> > this
> > > please let me know.  I'm willing to test any patches.
> >
> >
> > So it seems that commit
> >
> >  commit 2cb078603abb612e3bcd428fb8122c3d39e08832
> >  Author: Jeremy Fitzhardinge <jeremy@...p.org>
> >  Date:   Wed Jul 22 09:59:35 2009 -0700
> >
> >     x86, amd: Don't probe for extended APIC ID if APICs are disabled
> >
> >     If we've logically disabled apics, don't probe the PCI space for
> > the
> >     AMD extended APIC ID.
> >
> >     [ Impact: prevent boot crash under Xen. ]
> >
> >     Signed-off-by: Jeremy Fitzhardinge
> <jeremy.fitzhardinge@...rix.com>
> >     Reported-by: Bastian Blank <bastian@...di.eu.org>
> >     Signed-off-by: H. Peter Anvin <hpa@...or.com>
> >
> > needs to be added to 2.6.30.y for proper boot under Xen.
> > James, can you test this please?
> 
> Hi Andreas,
> 
> That commit won't apply directly on top of 2.6.30.5 as the #ifdef
which
> contains it is missing.  However, based on what you suggested I have
> the following patch below which resolves the problem for me.  Here's
> hoping it doesn't get munged by my mailer...
> 
> James
> 
> diff --git a/arch/x86/include/asm/cpufeature.h
> b/arch/x86/include/asm/cpufeature.h
> index bb83b1c..2f5ebf1 100644
> --- a/arch/x86/include/asm/cpufeature.h
> +++ b/arch/x86/include/asm/cpufeature.h
> @@ -94,6 +94,7 @@
>  #define X86_FEATURE_TSC_RELIABLE (3*32+23) /* TSC is known to be
> reliable */
>  #define X86_FEATURE_NONSTOP_TSC        (3*32+24) /* TSC does not stop
> in C states */
>  #define X86_FEATURE_CLFLUSH_MONITOR (3*32+25) /* "" clflush reqd with
> monitor */
> +#define X86_FEATURE_EXTD_APICID (3*32+26) /* has extended APICID (8
> bits) */
> 
>  /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4
*/
>  #define X86_FEATURE_XMM3       (4*32+ 0) /* "pni" SSE-3 */
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 0a9092f..61a592e 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -6,6 +6,7 @@
>  #include <asm/processor.h>
>  #include <asm/apic.h>
>  #include <asm/cpu.h>
> +#include <asm/pci-direct.h>
> 
>  #ifdef CONFIG_X86_64
>  # include <asm/numa_64.h>
> @@ -353,6 +354,15 @@ static void __cpuinit early_init_amd(struct
> cpuinfo_x86 *c)
>                     (c->x86_model == 8 && c->x86_mask >= 8))
>                         set_cpu_cap(c, X86_FEATURE_K6_MTRR);
>  #endif
> +#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_PCI)
> +       /* check CPU config space for extended APIC ID */
> +       if (cpu_has_apic && c->x86 >= 0xf) {
> +               unsigned int val;
> +               val = read_pci_config(0, 24, 0, 0x68);
> +               if ((val & ((1 << 17) | (1 << 18))) == ((1 << 17) | (1
> << 18)))
> +                       set_cpu_cap(c, X86_FEATURE_EXTD_APICID);
> +       }
> +#endif
>  }
> 
>  static void __cpuinit init_amd(struct cpuinfo_x86 *c)
> 

Ok - my mistake.  I'm a unfamiliar with git so after I reverted the
commit I was testing I thought that a reset would take it back to the
unmodified 2.6.30.5 release.  In fact the commit
2cb078603abb612e3bcd428fb8122c3d39e08832 does apply directly on top of
this and solves the problem.

Thanks,
James

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