Intel E5310 Specification Update - Page 50

32e guest" VM-entry control set to 1 in the SMM VMCS and the "host address-space size" VM-exit control cleared to 0 in the executive VMCS. Implication: A VM Exit will occur when a VMX Abort was expected. Workaround: An SMM VMM should always set the "IA-32e guest" VM-entry control in the SMM VMCS to be the value that was in the LMA bit (IA32_EFER.LMA.LMA[bit 10]) in the IA32_EFER MSR (C0000080H) at the time of the last SMM VM exit. If this guideline is followed, that value will be 1 only if the "host address-space size" VM-exit control is 1 in the executive VMCS. Status: For the steppings affected, see the Summary Tables of Changes. AJ124. Not-Present Page Faults May Set the RSVD Flag in the Error Code Problem: Not-Present Page Faults May Set the RSVD Flag in the Error Code Implication: Software may erroneously infer that a page fault was due to a reserved-bit violation when it was actually due to an attempt to access a not-present page. Intel has not observed this erratum with any commercially available software. Workaround: Page-fault handlers should ignore the RSVD flag in the error code if the P flag is 0. Status: For the steppings affected, see the Summary Tables of Changes. AJ125. VM Exits Due to "NMI-Window Exiting" May Be Delayed by One Instruction Problem: If VM entry is executed with the "NMI-window exiting" VM-execution control set to 1, a VM exit with exit reason "NMI window" should occur before execution of any instruction if there is no virtual-NMI blocking, no blocking of events by MOV SS, and no blocking of events by STI. If VM entry is made with no virtual-NMI blocking but with blocking of events by either MOV SS or STI, such a VM exit should occur after execution of one instruction in VMX non-root operation. Due to this erratum, the VM exit may be delayed by one additional instruction. Implication: VMM software using "NMI-window exiting" for NMI virtualization should generally be unaffected, as the erratum causes at most a one-instruction delay in the injection of a virtual NMI, which is virtually asynchronous. The erratum may affect VMMs relying on deterministic delivery of the affected VM exits. Workaround: None identified. Status: For the steppings affected, see the Summary Tables of Changes. AG126. FP Data Operand Pointer May Be Incorrectly Calculated After an FP Access Which Wraps a 4-Gbyte Boundary in Code That Uses 32-Bit Address Size in 64-bit Mode Problem: The FP (Floating Point) Data Operand Pointer is the effective address of the operand associated with the last non-control FP instruction executed by the processor. If an 80bit FP access (load or store) uses a 32-bit address size in 64-bit mode and the memory access wraps a 4-Gbyte boundary and the FP environment is subsequently saved, the value contained in the FP Data Operand Pointer may be incorrect. Implication: Due to this erratum, the FP Data Operand Pointer may be incorrect. Wrapping an 80-bit FP load around a 4-Gbyte boundary in this way is not a normal programming practice. Intel has not observed this erratum with any commercially available software. Workaround: If the FP Data Operand Pointer is used in a 64-bit operating system which may run code accessing 32-bit addresses, care must be taken to ensure that no 80-bit FP accesses are wrapped around a 4-Gbyte boundary. Status: For the steppings affected, see the Summary Table of Changes. 50 Intel® Xeon® Processor 5300 Series Specification Update, December 2010