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Date: Tue, 2 Sep 2008 20:27:06 -0700
From: Greg KH <gregkh@...e.de>
To: Yinghai Lu <yhlu.kernel@...il.com>
Cc: mingo@...e.hu, stable@...nel.org, stable-commits@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: patch x86-work-around-mtrr-mask-setting.patch added to
2.6.26-stable tree
On Tue, Sep 02, 2008 at 05:54:10PM -0700, Yinghai Lu wrote:
> On Tue, Sep 2, 2008 at 5:26 PM, <gregkh@...e.de> 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@...nel.org Tue Sep 2 17:14:12 2008
> > From: Yinghai Lu <yhlu.kernel@...il.com>
> > Date: Fri, 22 Aug 2008 17:40:05 GMT
> > Subject: x86: work around MTRR mask setting
> > To: jejb@...nel.org, stable@...nel.org
> > Message-ID: <200808221740.m7MHe5ud013727@...a.kernel.org>
> >
> > From: Yinghai Lu <yhlu.kernel@...il.com>
> >
> > 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@...il.com>
> > Signed-off-by: Ingo Molnar <mingo@...e.hu>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> >
> > ---
> > 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@...il.com are
> >
> > queue-2.6.26/x86-work-around-mtrr-mask-setting.patch
>
>
> please put
>
> commit 9754a5b840a209bc1f192d59f63e81b698a55ac8
> Author: Ingo Molnar <mingo@...e.hu>
> 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@...e.hu>
>
> 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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