Update

Intel
®
Xeon
®
Processor E7-8800/4800/2800 Product Families 31
Specification Update November 2014
Workaround: Software that has executed in 64-bit mode should reload CR3 with a 32-bit value
before returning to 32-bit paging.
Status: For the steppings affected, see the Summary Tables of Changes.
BP55. EPT Violations May Report Bits 11:0 of Guest Linear Address
Incorrectly
Problem: If a memory access to a linear address requires the processor to update an accessed or
dirty flag in a paging-structure entry and if that update causes an EPT violation, the
processor should store the linear address into the “guest linear address” field in the
VMCS. Due to this erratum, the processor may store an incorrect value into bits 11:0 of
this field. (The processor correctly stores the guest-physical address of the paging-
structure entry into the “guest-physical address” field in the VMCS.)
Implication: Software may not be easily able to determine the page offset of the original memory
access that caused the EPT violation. Intel has not observed this erratum to impact the
operation of any commercially available software.
Workaround: Software requiring the page offset of the original memory access address can derive it
by simulating the effective address computation of the instruction that caused the EPT
violation.
Status: For the steppings affected, see the Summary Tables of Changes.
BP56. IA32_VMX_VMCS_ENUM MSR (48AH) Does Not Properly Report The
Highest Index Value Used For VMCS Encoding
Problem: IA32_VMX_VMCS_ENUM MSR (48AH) bits 9:1 report the highest index value used for
any VMCS encoding. Due to this erratum, the value 21 is returned in bits 9:1 although
there is a VMCS field whose encoding uses the index value 23.
Implication: Software that uses the value reported in IA32_VMX_VMCS_ENUM[9:1] to read and
write all VMCS fields may omit one field.
Workaround: None identified.
Status: For the steppings affected, see the Summary Tables of Changes.
BP57. Virtual-APIC Page Accesses With 32-Bit PAE Paging May Cause a
System Crash
Problem: If a logical processor has EPT (Extended Page Tables) enabled, is using 32-bit PAE
paging, and accesses the virtual-APIC page then a complex sequence of internal
processor micro-architectural events may cause an incorrect address translation or
machine check on either logical processor.
Implication: This erratum may result in unexpected faults, an uncorrectable TLB error logged in
IA32_MCi_STATUS.MCACOD (bits [15:0]) with a value of 0000_0000_0001_xxxxb
(where x stands for 0 or 1), a guest or hypervisor crash, or other unpredictable system
behavior.
Workaround: It is possible for the BIOS to contain a workaround for this erratum.
Status: For the steppings affected, see the Summary Tables of Changes.
BP58. VM Exit May Set IA32_EFER.NXE When IA32_MISC_ENABLE Bit 34 is
Set to 1
Problem: When “XD Bit Disable” in the IA32_MISC_ENABLE MSR (1A0H) bit 34 is set to 1, it
should not be possible to enable the “execute disable” feature by setting
IA32_EFER.NXE. Due to this erratum, a VM exit that occurs with the 1-setting of the
“load IA32_EFER” VM-exit control may set IA32_EFER.NXE even if IA32_MISC_ENABLE
bit 34 is set to 1. This erratum can occur only if IA32_MISC_ENABLE bit 34 was set by
guest software in VMX non-root operation.