Intel X5472 Specification Update - Page 18

Errata AX1. EFLAGS Discrepancy on Page Fault After Translation Change Problem: This erratum is regarding the case where paging structures are modified to change a linear address from writable to non-writable without software performing an appropriate TLB invalidation. When a subsequent access to that address by a specific instruction (ADD, AND, BTC, BTR, BTS, CMPXCHG, DEC, INC, NEG, NOT, OR, ROL/ROR, SAL/SAR/SHL/SHR, SHLD, SHRD, SUB, XOR, and XADD) causes a page fault, the value saved for EFLAGS may incorrectly contain the arithmetic flag values that the EFLAGS register would have held had the instruction completed without fault. This can occur even if the fault causes a VM exit or if its delivery causes a nested fault. Implication: None identified. Although the EFLAGS value saved may contain incorrect arithmetic flag values, Intel has not identified software that is affected by this erratum. This erratum will have no further effects once the original instruction is restarted because the instruction will produce the same results as if it had initially completed without a page fault. Workaround: If the page fault handler inspects the arithmetic portion of the saved EFLAGS value, then system software should perform a synchronized paging structure modification and TLB invalidation. Status: For the steppings affected, see the Summary Tables of Changes. AX2. INVLPG Operation for Large (2M/4M) Pages May be Incomplete under Certain Conditions Problem: The INVLPG instruction may not completely invalidate Translation Look-aside Buffer (TLB) entries for large pages (2M/4M) when both of the following conditions exist: "Address range of the page being invalidated spans several Memory Type Range Registers (MTRRs) with different memory types specified "INVLPG operation is preceded by a Page Assist Event (Page Fault (#PF) or an access that results in either A or D bits being set in a Page Table Entry (PTE)). Implication: Stale translations may remain valid in TLB after a PTE update resulting in unpredictable system behavior. Intel has not observed this erratum with any commercially available software. Workaround: Software should ensure that the memory type specified in the MTRRs is the same for the entire address range of the large page. Status: For the steppings affected, see the Summary Tables of Changes. AX3. Store to WT Memory Data May be Seen in Wrong Order by Two Subsequent Loads Problem: When data of Store to WT memory is used by two subsequent loads of one thread and another thread performs cacheable write to the same address the first load may get the data from external memory or L2 written by another core, while the second load will get the data straight from the WT Store. Implication: Software that uses WB to WT memory aliasing may violate proper store ordering. Workaround: Do not use WB to WT aliasing. Status: For the steppings affected, see the Summary Tables of Changes. Intel® Xeon® Processor 5400 Series 18 Specification Update