From: Zhao Yakui <yakui.zhao@xxxxxxxxx> 991528d7348667924176f3e29addea0675298944 (ACPI: Processor native C-states using MWAIT) started passing C2C3_FFH to _PDC to tell the BIOS that Linux supports MWAIT for deep C-states. However, we should first double check with the hardware that it actually supports MWAIT before potentially exposing a BIOS bug of an MWAIT _CST on HW that doesn't support MWAIT. Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx> Signed-off-by: Li Shaohua <shaohua.li@xxxxxxxxx> Signed-off-by: Len Brown <len.brown@xxxxxxxxx> --- arch/x86/kernel/acpi/processor.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/acpi/processor.c b/arch/x86/kernel/acpi/processor.c index de2d2e4..7c074ee 100644 --- a/arch/x86/kernel/acpi/processor.c +++ b/arch/x86/kernel/acpi/processor.c @@ -56,6 +56,12 @@ static void init_intel_pdc(struct acpi_processor *pr, struct cpuinfo_x86 *c) if (cpu_has(c, X86_FEATURE_ACPI)) buf[2] |= ACPI_PDC_T_FFH; + /* + * If mwait/monitor is unsupported, C2/C3_FFH will be disabled + */ + if (!cpu_has(c, X86_FEATURE_MWAIT)) + buf[2] &= ~(ACPI_PDC_C_C2C3_FFH); + obj->type = ACPI_TYPE_BUFFER; obj->buffer.length = 12; obj->buffer.pointer = (u8 *) buf; -- 1.5.6.1.89.gd544 -- 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
