Re: patch x86-work-around-mtrr-mask-setting.patch added to2.6.26-stable tree

[Greg KH]

On Tue, Sep 02, 2008 at 05:54:10PM -0700, Yinghai Lu wrote:
> On Tue, Sep 2, 2008 at 5:26 PM,  <gregkh@xxxxxxx> wrote:
> >
> > This is a note to let you know that we have just queued up the patch titled
> >
> >    Subject: x86: work around MTRR mask setting
> >
> > to the 2.6.26-stable tree.  Its filename is
> >
> >    x86-work-around-mtrr-mask-setting.patch
> >
> > A git repo of this tree can be found at
> >    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> >
> >
> > From jejb@xxxxxxxxxx  Tue Sep  2 17:14:12 2008
> > From: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
> > Date: Fri, 22 Aug 2008 17:40:05 GMT
> > Subject: x86: work around MTRR mask setting
> > To: jejb@xxxxxxxxxx, stable@xxxxxxxxxx
> > Message-ID: <200808221740.m7MHe5ud013727@xxxxxxxxxxxxxxx>
> >
> > From: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
> >
> > commit 38cc1c3df77c1bb739a4766788eb9fa49f16ffdf upstream
> >
> > Joshua Hoblitt reported that only 3 GB of his 16 GB of RAM is
> > usable. Booting with mtrr_show showed us the BIOS-initialized
> > MTRR settings - which are all wrong.
> >
> > So the root cause is that the BIOS has not set the mask correctly:
> >
> >>               [    0.429971]  MSR00000200: 00000000d0000000
> >>               [    0.433305]  MSR00000201: 0000000ff0000800
> >> should be ==> [    0.433305]  MSR00000201: 0000003ff0000800
> >>
> >>               [    0.436638]  MSR00000202: 00000000e0000000
> >>               [    0.439971]  MSR00000203: 0000000fe0000800
> >> should be ==> [    0.439971]  MSR00000203: 0000003fe0000800
> >>
> >>               [    0.443304]  MSR00000204: 0000000000000006
> >>               [    0.446637]  MSR00000205: 0000000c00000800
> >> should be ==> [    0.446637]  MSR00000205: 0000003c00000800
> >>
> >>               [    0.449970]  MSR00000206: 0000000400000006
> >>               [    0.453303]  MSR00000207: 0000000fe0000800
> >> should be ==> [    0.453303]  MSR00000207: 0000003fe0000800
> >>
> >>               [    0.456636]  MSR00000208: 0000000420000006
> >>               [    0.459970]  MSR00000209: 0000000ff0000800
> >> should be ==> [    0.459970]  MSR00000209: 0000003ff0000800
> >
> > So detect this borkage and add the prefix 111.
> >
> > Signed-off-by: Yinghai Lu <yhlu.kernel@xxxxxxxxx>
> > Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
> >
> > ---
> >  arch/x86/kernel/cpu/mtrr/generic.c |   15 +++++++++++++--
> >  1 file changed, 13 insertions(+), 2 deletions(-)
> >
> > --- a/arch/x86/kernel/cpu/mtrr/generic.c
> > +++ b/arch/x86/kernel/cpu/mtrr/generic.c
> > @@ -365,6 +365,7 @@ static void generic_get_mtrr(unsigned in
> >                             unsigned long *size, mtrr_type *type)
> >  {
> >        unsigned int mask_lo, mask_hi, base_lo, base_hi;
> > +       unsigned int tmp, hi;
> >
> >        rdmsr(MTRRphysMask_MSR(reg), mask_lo, mask_hi);
> >        if ((mask_lo & 0x800) == 0) {
> > @@ -378,8 +379,18 @@ static void generic_get_mtrr(unsigned in
> >        rdmsr(MTRRphysBase_MSR(reg), base_lo, base_hi);
> >
> >        /* Work out the shifted address mask. */
> > -       mask_lo = size_or_mask | mask_hi << (32 - PAGE_SHIFT)
> > -           | mask_lo >> PAGE_SHIFT;
> > +       tmp = mask_hi << (32 - PAGE_SHIFT) | mask_lo >> PAGE_SHIFT;
> > +       mask_lo = size_or_mask | tmp;
> > +       /* Expand tmp with high bits to all 1s*/
> > +       hi = fls(tmp);
> > +       if (hi > 0) {
> > +               tmp |= ~((1<<(hi - 1)) - 1);
> > +
> > +               if (tmp != mask_lo) {
> > +                       WARN_ON("mtrr: your BIOS has set up an incorrect mask, fixing it up.\n");
> > +                       mask_lo = tmp;
> > +               }
> > +       }
> >
> >        /* This works correctly if size is a power of two, i.e. a
> >           contiguous range. */
> >
> >
> > Patches currently in stable-queue which might be from yhlu.kernel@xxxxxxxxx are
> >
> > queue-2.6.26/x86-work-around-mtrr-mask-setting.patch
> 
> 
> please put
> 
> commit 9754a5b840a209bc1f192d59f63e81b698a55ac8
> Author: Ingo Molnar <mingo@xxxxxxx>
> Date:   Fri Aug 22 08:22:23 2008 +0200
> 
>     x86: work around MTRR mask setting, v2
> 
>     improve the debug printout:
> 
>     - make it actually display something
>     - print it only once
> 
>     would be nice to have a WARN_ONCE() facility, to feed such things to
>     kerneloops.org.
> 
>     Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> 
> diff --git a/arch/x86/kernel/cpu/mtrr/generic.c
> b/arch/x86/kernel/cpu/mtrr/generic.c
> index 43102e0..cb7d3b6 100644
> --- a/arch/x86/kernel/cpu/mtrr/generic.c
> +++ b/arch/x86/kernel/cpu/mtrr/generic.c
> @@ -401,7 +401,12 @@ static void generic_get_mtrr(unsigned int reg,
> unsigned long *base,
>                 tmp |= ~((1<<(hi - 1)) - 1);
> 
>                 if (tmp != mask_lo) {
> -                       WARN_ON("mtrr: your BIOS has set up an
> incorrect mask, fixing it up.\n");
> +                       static int once = 1;
> +
> +                       if (once) {
> +                               printk(KERN_INFO "mtrr: your BIOS has
> set up an incorrect mask, fixing it up.\n");
> +                               once = 0;
> +                       }
>                         mask_lo = tmp;
>                 }
>         }
> 
> into stable too....
> otherwise WARN_ON will keep dump calling stack..

Ok, will add it to the queue.

thanks,

greg k-h
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