Intel I3-530 Specifications - Page 26

Reported Memory Type May Not Be Used to Access the VMCS

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AAU30. Reported Memory Type May Not Be Used to Access the VMCS and Referenced Data Structures Problem: Bits 53:50 of the IA32_VMX_BASIC MSR report the memory type that the processor uses to access the VMCS and data structures referenced by pointers in the VMCS. Due to this erratum, a VMX access to the VMCS or referenced data structures will instead use the memory type that the MTRRs (memory-type range registers) specify for the physical address of the access. Implication: Bits 53:50 of the IA32_VMX_BASIC MSR report that the WB (write-back) memory type will be used but the processor may use a different memory type. Workaround: Software should ensure that the VMCS and referenced data structures are located at physical addresses that are mapped to WB memory type by the MTRRs. Status: For the steppings affected, see the Summary Tables of Changes. AAU31. Changing the Memory Type for an In-Use Page Translation May Lead to Memory-Ordering Violations Problem: Under complex microarchitectural conditions, if software changes the memory type for data being actively used and shared by multiple threads without the use of semaphores or barriers, software may see load operations execute out of order. Implication: Memory ordering may be violated. Intel has not observed this erratum with any commercially-available software. Workaround: Software should ensure pages are not being actively used before requesting their memory type be changed. Status: For the steppings affected, see the Summary Tables of Changes. AAU32. Erratum AAU32 added to this specification Update in error; all erratum details removed from the specification update document. 26 Specification Update

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26
Specification Update
AAU30.
Reported Memory Type May Not Be Used to Access the VMCS and
Referenced Data Structures
Problem:
Bits 53:50 of the IA32_VMX_BASIC MSR report the memory type that the processor
uses to access the VMCS and data structures referenced by pointers in the VMCS. Due
to this erratum, a VMX access to the VMCS or referenced data structures will instead
use the memory type that the MTRRs (memory-type range registers) specify for the
physical address of the access.
Implication:
Bits 53:50 of the IA32_VMX_BASIC MSR report that the WB (write-back) memory type
will be used but the processor may use a different memory type.
Workaround:
Software should ensure that the VMCS and referenced data structures are located at
physical addresses that are mapped to WB memory type by the MTRRs.
Status:
For the steppings affected, see the Summary Tables of Changes.
AAU31.
Changing the Memory Type for an In-Use Page Translation May Lead
to Memory-Ordering Violations
Problem:
Under complex microarchitectural conditions, if software changes the memory type for
data being actively used and shared by multiple threads without the use of semaphores
or barriers, software may see load operations execute out of order.
Implication:
Memory ordering may be violated. Intel has not observed this erratum with any
commercially-available software.
Workaround:
Software should ensure pages are not being actively used before requesting their
memory type be changed.
Status:
For the steppings affected, see the Summary Tables of Changes.
AAU32.
Erratum AAU32 added to this specification Update in error; all erratum
details removed from the specification update document.