CPUID Modifications for Intel Processors

CPUID modifications for Intel processors

0x00000000

EAX

Highest value

Minimum of the actual hardware value and 0x00000006.

EBX

ECX

EDX

Vendor ID

Unmodified.

0x00000001

EAX

Processor signature

Unmodified for the root partition, set as the minimum otherwise (for more information about this signature, see Family, Model and Stepping Reported by CPUID).

EBX

Miscellaneous information

Bits 0-7: Brand ID, unmodified.

Bits 8-15: Chunks, unmodified.

Bits 16-23: Count, unmodified if the DeprecatedExposeHyperthreads flag was specified at partition creation, one otherwise. [For the root partition, this field is always unmodified.]

Bits 24-31: APIC ID modified to match low-order 8 bits of initial APIC ID of the virtual processor. [For the root partition, this field is unmodified.]

ECX

Feature flags

Bit 0: SSE3, unmodified.

Bit 1: reserved, cleared.

Bit 2: reserved, cleared.

Bit 3: MONITOR, cleared.

Bit 4: DS-CPL, cleared.

Bit 5: VMX, cleared.

Bit 6: reserved, cleared.

Bit 7: EST, unmodified for the root partition and cleared for others. Indicates whether the underlying logical processor supports speed step technology.

Bit 8: TM2, unmodified for the root partition and cleared for others. Indicates whether the underlying logical processor supports the Thermal Monitor 2 thermal control circuit (TCC).

Bit 9: SSSE3, unmodified.

Bit 10: CID, cleared.

Bit 11: reserved, cleared.

Bit 12: reserved, cleared.

Bit 13: CX16, unmodified.

Bit 14: xTPR, unmodified.

Bit 15-30: reserved, cleared.

Bit 31: if set, indicates that a hypervisor is present.

EDX

Feature information

Bit 0: FPU, unmodified.

Bit 1: VME, unmodified.

Bit 2: DE, unmodified.

Bit 3: PSE, unmodified.

Bit 4: TSC, unmodified.

Bit 5: MSR, unmodified.

Bit 6: PAE, unmodified.

Bit 7: MCE, unmodified.

Bit 8: CX8, unmodified.

Bit 9: APIC, unmodified.

Bit 10: reserved, cleared.

Bit 11: SEP, unmodified.

Bit 12: MTRR, set.

Bit 13: PGE, unmodified.

Bit 14: MCA, unmodified for root, cleared otherwise.

Bit 15: CMOV, unmodified.

Bit 16: PAT, unmodified.

Bit 17: PSE-36, unmodified.

Bit 18: PSN, cleared.

Bit 19: CLFSH, unmodified.

Bit 20: reserved, cleared.

Bit 21: DS, cleared.

Bit 22: ACPI, unmodified for the root partition, cleared otherwise.

Bit 23: MMX, unmodified.

Bit 24: FXSR, unmodified.

Bit 25: SSE, unmodified.

Bit 26: SSE2, unmodified.

Bit 27: SS, cleared.

Bit 28: HTT, unmodified if the DeprecatedExposeHyperthreads flag was specified at partition creation, cleared otherwise.

Bit 29: TM, unmodified for the root partition, cleared otherwise.

Bit 30: IA64, cleared.

Bit 31: PBE, cleared.

0x00000002

All

Cache and TLB descriptors

Unmodified.

0x00000003

All

Processor serial number

Cleared.

0x00000004

All

Deterministic cache parameters function

Unmodified.

0x00000005

All

MONITOR/MWAIT

Cleared.

0x00000006

All

Power management feature enumeration function

Unmodified for the partition possessing the CPUManagement privilege (root), cleared otherwise.

0x80000000

EAX

Maximum input value for extended function CPUID information

Minimum of the actual hardware value and 0x80000008.

EBX

ECX

EDX

Reserved

Cleared.

0x80000001

EAX

EBX

Reserved

Cleared.

ECX

Extended feature flags

Bit 0: LAHF/SAHF, unmodified.

Bits 1-31: reserved, cleared.

EDX

Extended feature flags

Bits 0-10: reserved, cleared.

Bit 11: SYSCALL, unmodified.

Bit 12-19: reserved, cleared.

Bit 20: XD, unmodified.

Bits 21-28: reserved, cleared.

Bit 29: EM64T, unmodified.

Bits 30-31: reserved, cleared.

0x80000002 through 0x80000004

All

Processor brand string

Unmodified.

0x80000005

All

Reserved

Cleared.

0x80000006

All

Extended L2 cache features function

Unmodified.

0x80000007

All

Reserved

Cleared.

0x80000008

EAX

Extended address sizes function

Bits 0-7: physical address size, modified to indicate the size of the GPA space that is supported (for the root partition this is unmodified).

Bits 8-15: virtual address size, modified to indicate the size of the GVA space supported by the hypervisor (for the root partition this is unmodified).

Bits 16-31: reserved, cleared.

EBX

ECX

EDX

Reserved

Cleared.