CPUID Execution

The behavior of the CPUID instruction might differ from the behavior of the same instruction on a logical processor.

The following pseudo-code defines the different behaviors that can result from the execution of a CPUID instruction by a virtual processor.

if an intercept has been set for the CPUID instruction for
 the index specified in EAX {
 Suspend VP and send message to parent (CPUID Intercept)
}
else {
 CPUID instruction returns information as dictated by the
 logical processor and the hypervisor
}

The hypervisor might override the standard CPUID information that is returned by the logical processor. The following sections detail the ways in which CPUID information is modified by the hypervisor. In some cases, the CPUID values that are returned to the root partition differ from non-root partitions. In such cases, the differences are noted.

Note   The hypervisor does not attempt to dictate a processor selection or to standardize on a particular processor model. The manipulation of various CPUID output is used to accommodate processor specifics or to reflect limitations on the partition's accessibility or privilege to use certain processor features.

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Build date: 11/16/2013