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AAZ99.
VM Exit May Incorrectly Clear IA32_PERF_GLOBAL_CTRL [34:32]
Problem:
If the "load IA32_PERF_GLOBAL_CTRL" VM-exit control is 1, a VM exit should load the
IA32_PERF_GLOBAL_CTRL MSR (38FH) from the IA32_PERF_GLOBAL_CTRL field in the
guest-state area of the VMCS. Due to this erratum, such a VM exit may instead clear
bits 34:32 of the MSR, loading only bits 31:0 from the VMCS.
Implication: All fixed-function performance counters will be disabled after an affected VM exit, even
if the VM exit should have enabled them based on the IA32_PERF_GLOBAL_CTRL field
in the guest-state area of the VMCS.
Workaround:VM monitor that wants the fixed-function performance counters to be enabled after a
VM exit may do one of two things: (1) clear the "load IA32_PERF_GLOBAL_CTRL" VM-
exit control; or (2) include an entry for the IA32_PERF_GLOBAL_CTRL MSR in the VM-
exit MSR-load list.
Status:
For the steppings affected, see the Summary Tables of Changes.
AAZ100.
DTS Temperature Data May Be Incorrect On a Return From the
Package C6 Low Power State
Problem:
The DTS (Digital Thermal Sensor) temperature value may be incorrect for a small
period of time (less than 2ms) after a return from the package C6 low power state.
Implication: The DTS temperature data (including temperatures read by Platform Environment
Control Interface) may be reported lower than the actual temperature. Fan speed
control or other system functions which are reliant on correct DTS temperature data
may behave unpredictably.
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.
AAZ101.
USB Devices May Not Function Properly With Integrated Graphics
While Running Targeted Stress Graphics Workloads With Non-
Matching Memory Configurations
Problem:
When the integrated graphics engine continuously generates a large stream of writes to
system memory, and Intel Flex Memory Technology is enabled, with a different mount
of memory in each channel, the memory arbiter may temporarily stop servicing other
device-initiated traffic. In some cases this can cause certain USB devices, such as
keyboard and mouse, to become unresponsive. Intel has only observed this erratum
with targeted stress content. This erratum is not seen when the platform is configured
with single channel or dual channel symmetric memory and is not dependent on the
memory frequency.
Implication: Due to this erratum, certain USB devices may become unresponsive.
Workaround:None identified.
Status:
For the steppings affected, see the Summary Tables of Changes.
AAZ102.
VM Entry May Omit Consistency Checks Related to Bit 14 (BS) of
thePending Debug Exception Field in Guest-State Area of the VMCS
Problem:
Section "Checks on Guest Non-Register State" of Volume 3B specifies consistency
checks that VM entry should perform for bit 14 (BS, indicating a pending single-step
exception) of the pending debug exception field in guest-state area of the VMCS. These
checks enforce the consistency of that bit with other fields in the guest-state area. Due
to this erratum, VM entry may fail to perform these checks.
Implication: A logical processor may enter VMX non-root operation with a pending single-step
debug exception that not consistent other register state; this may result in unexpected
behavior. Intel has not observed this erratum with any commercially available
software..
42
Errata
Specification Update
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