> -----Original Message----- > From: Andy Lutomirski [mailto:luto@xxxxxxx] > Sent: Saturday, August 06, 2011 4:43 AM > To: x86@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Cc: Yu, Fenghua; Matthew Garrett; Len Brown; linux- > acpi@xxxxxxxxxxxxxxx; Ingo Molnar; Andy Lutomirski > Subject: [PATCH v2 1/2] x86: Enable fast strings on Intel if BIOS > hasn't already > > Intel SDM volume 3A, 8.4.2 says: > > Software can disable fast-string operation by clearing the > fast-string-enable bit (bit 0) of IA32_MISC_ENABLE MSR. > However, Intel recomments that system software always enable > fast-string operation. > > The Intel DQ67SW board (with latest BIOS) disables fast string > operations if TXT is enabled. A Lenovo X220 disables it regardless > of TXT setting. I doubt I'm the only person with a dumb BIOS like > this. > > Signed-off-by: Andy Lutomirski <luto@xxxxxxx> > --- > arch/x86/kernel/cpu/intel.c | 25 ++++++++++++++++++++++--- > 1 files changed, 22 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c > index ed6086e..c80ab41 100644 > --- a/arch/x86/kernel/cpu/intel.c > +++ b/arch/x86/kernel/cpu/intel.c > @@ -30,6 +30,7 @@ > static void __cpuinit early_init_intel(struct cpuinfo_x86 *c) > { > u64 misc_enable; > + bool allow_fast_string = true; > > /* Unmask CPUID levels if masked: */ > if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) { > @@ -118,8 +119,9 @@ static void __cpuinit early_init_intel(struct > cpuinfo_x86 *c) > * (model 2) with the same problem. > */ > if (c->x86 == 15) { > - rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); > + allow_fast_string = false; > > + rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); > if (misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING) { > printk(KERN_INFO "kmemcheck: Disabling fast string > operations\n"); > > @@ -130,11 +132,28 @@ static void __cpuinit early_init_intel(struct > cpuinfo_x86 *c) > #endif > > /* > - * If fast string is not enabled in IA32_MISC_ENABLE for any > reason, > - * clear the fast string and enhanced fast string CPU > capabilities. > + * If BIOS didn't enable fast string operation, try to enable > + * it ourselves. If that fails, then clear the fast string > + * and enhanced fast string CPU capabilities. > */ > if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) { > rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); > + > + if (allow_fast_string && > + !(misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING)) { > + misc_enable |= MSR_IA32_MISC_ENABLE_FAST_STRING; > + wrmsr_safe(MSR_IA32_MISC_ENABLE, (u32)misc_enable, > + (u32)(misc_enable >> 32)); > + > + /* Re-read to make sure it stuck. */ > + rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable); > + > + if (misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING) > + printk(KERN_WARNING FW_WARN "CPU #%d: " > + "IA32_MISC_ENABLE.FAST_STRING_ENABLE " > + "was not set", c->cpu_index); This printk is redundant because the same info is dumped in the below printk. Plus it's not firmware's issue if we can not set fast string bit 0 in MISC_ENABLE register. So I don't think FW_WARN is right. I would suggest to remove this printk (and the if () statement) and change KERN_INFO to KERN_WARNING in the following printk. > + } > + > if (!(misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING)) { > printk(KERN_INFO "Disabled fast string > operations\n"); > setup_clear_cpu_cap(X86_FEATURE_REP_GOOD); > -- > 1.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
