Re: [Xen-devel] [PATCH] xen: msr safe cleanup

[Christoph Egger <Christoph.Egger@xxxxxxx>]

On Friday 11 June 2010 14:23:58 Joerg Roedel wrote:
> On Fri, Jun 11, 2010 at 12:11:21PM +0200, Christoph Egger wrote:
> > -   if ((rdmsr_safe(MSR_K8_ENABLE_C1E, lo, hi) == 0) &&
> > -       (lo & (3u << 27)) &&
> > -       (wrmsr_safe(MSR_K8_ENABLE_C1E, lo & ~(3u << 27), hi) != 0))
> > -           printk(KERN_ERR "Failed to disable C1E on CPU#%u (%08x)\n",
> > -                  smp_processor_id(), lo);
> > +   if ((rdmsr_safe(MSR_K8_ENABLE_C1E, msr_content) == 0) &&
> > +       (msr_content & (3u << 27)) &&
> > +       (wrmsr_safe(MSR_K8_ENABLE_C1E, msr_content & ~(3u << 27)) != 0))
> > +           printk(KERN_ERR "Failed to disable C1E on CPU#%u 
> > (%16"PRIx64")\n",
> > +                  smp_processor_id(), msr_content);
>
> Broken. Please use ull instead of just u in your masks, especially the
> last one.

Thanks for pointing this out. Attached patch fixes this.

Signed-off-by: Christoph Egger <Christoph.Egger@xxxxxxx>

>
> >  void mtrr_wrmsr(unsigned msr, unsigned a, unsigned b)
> >  {
> > -   if (wrmsr_safe(msr, a, b) < 0)
> > +   uint64_t msr_content;
> > +
> > +   msr_content = ((uint64_t)b << 32) | a;
> > +   if (wrmsr_safe(msr, msr_content) < 0)
> >             printk(KERN_ERR
> >                     "MTRR: CPU %u: Writing MSR %x to %x:%x failed\n",
> >                     smp_processor_id(), msr, a, b);
>
> Since you keep the two unsigned parameters of the function this change
> complicates the code more than it cleans up.

Fixed in c/s 21603.

Christoph



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Attachment: xen_msrsafe_fix.diff
Description: Text Data

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