Il 01/08/2014 02:57, Zhang, Yang Z ha scritto: > > TPR_THRESHOLD will be likely written as zero, but the processor will > > never use it anyway. It's just a small optimization because > > nested_cpu_has(vmcs12, CPU_BASED_TPR_SHADOW) will almost always be true. > > Theoretically, you are right. But we should not expect all VMMs > follow it. It is not worth to violate the SDM just for saving two or > three instructions' cost.
Yes, you do need an "if (cpu_has_vmx_tpr_shadow())" around the vmcs_write32. But still, checking nested_cpu_has is not strictly necessary. Right now they both are a single AND, but I have plans to change all of the cpu_has_*() checks to static keys. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
