Re: [Xen-devel] Ping: [PATCH] x86/Intel: work around Xeon 7400 series erratum AAI65

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich
> Sent: Wednesday, March 12, 2014 5:40 PM
> 
> >>> On 05.03.14 at 17:52, "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> > Linux commit 40e2d7f9b5dae048789c64672bf3027fbb663ffa ("x86 idle:
> > Repair large-server 50-watt idle-power regression") tells us that this
> > applie snot just to the named Xen 7400 series, but also NHM-EX and
> > WSM-EX; sadly Intel's documentation is so badly searchable that I
> > wasn't able to locate the respective errata (and hence can't quote
> > their numbers here).
> >
> > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

> >
> > --- a/xen/arch/x86/acpi/cpu_idle.c
> > +++ b/xen/arch/x86/acpi/cpu_idle.c
> > @@ -335,6 +335,9 @@ void mwait_idle_with_hints(unsigned int
> >      unsigned int cpu = smp_processor_id();
> >      s_time_t expires = per_cpu(timer_deadline, cpu);
> >
> > +    if ( boot_cpu_has(X86_FEATURE_CLFLUSH_MONITOR) )
> > +        clflush((void *)&mwait_wakeup(cpu));
> > +
> >      __monitor((void *)&mwait_wakeup(cpu), 0, 0);
> >      smp_mb();
> >
> > --- a/xen/arch/x86/cpu/intel.c
> > +++ b/xen/arch/x86/cpu/intel.c
> > @@ -147,6 +147,9 @@ void __devinit early_intel_workaround(st
> >  /*
> >   * P4 Xeon errata 037 workaround.
> >   * Hardware prefetcher may cause stale data to be loaded into the cache.
> > + *
> > + * Xeon 7400 erratum AAI65 (and further newer Xeons)
> > + * MONITOR/MWAIT may have excessive false wakeups
> >   */
> >  static void __devinit Intel_errata_workarounds(struct cpuinfo_x86 *c)
> >  {
> > @@ -161,6 +164,10 @@ static void __devinit Intel_errata_worka
> >                     wrmsr (MSR_IA32_MISC_ENABLE, lo, hi);
> >             }
> >     }
> > +
> > +   if (c->x86 == 6 && cpu_has_clflush &&
> > +       (c->x86_model == 29 || c->x86_model == 46 || c->x86_model ==
> 47))
> > +           set_bit(X86_FEATURE_CLFLUSH_MONITOR, c->x86_capability);
> >  }
> >
> >
> > --- a/xen/include/asm-x86/cpufeature.h
> > +++ b/xen/include/asm-x86/cpufeature.h
> > @@ -71,6 +71,7 @@
> >  #define X86_FEATURE_TSC_RELIABLE (3*32+12) /* TSC is known to be
> reliable */
> >  #define X86_FEATURE_XTOPOLOGY    (3*32+13) /* cpu topology enum
> extensions */
> >  #define X86_FEATURE_CPUID_FAULTING (3*32+14) /* cpuid faulting */
> > +#define X86_FEATURE_CLFLUSH_MONITOR (3*32+15) /* clflush reqd with
> monitor */
> >
> >  /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
> >  #define X86_FEATURE_XMM3   (4*32+ 0) /* Streaming SIMD Extensions-3
> */
> 
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel