[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] x86/Intel: work around Xeon 7400 series erratum AAI65
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> --- 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 */ Attachment:
x86-monitor-clflush-workaround.patch _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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