From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH] x86/Intel: work around Xeon 7400 series erratum AAI65 Date: Wed, 5 Mar 2014 17:19:47 +0000 Message-ID: <53175CB3.3070907@citrix.com> References: <53176474020000780012146F@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============5416783424931023001==" Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WLFUG-0004Kq-QL for xen-devel@lists.xenproject.org; Wed, 05 Mar 2014 17:20:09 +0000 In-Reply-To: <53176474020000780012146F@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel , Keir Fraser , Donald D Dugger , Jun Nakajima List-Id: xen-devel@lists.xenproject.org --===============5416783424931023001== Content-Type: multipart/alternative; boundary="------------090502060308090503070308" --------------090502060308090503070308 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit On 05/03/14 16:52, Jan Beulich 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 "applies not" "named Xeon 7400 series" > 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 content Reviewed-by: Andrew Cooper > > --- 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@lists.xen.org > http://lists.xen.org/xen-devel --------------090502060308090503070308 Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit
On 05/03/14 16:52, Jan Beulich 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

"applies not" "named Xeon 7400 series"

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@suse.com>

content Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>


--- 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 */






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