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Volume 2, Part 1: Processor Abstraction Layer
2:345
There is no synchronization requirement for the virtualization of
probe
instructions.
11.7.4.2.9 Test Feature Optimization
The test feature optimization is enabled by the a_tf bit in the Virtualization Acceleration
Control (
vac
) field in the VPD.
When this optimization is enabled, test feature (
tf
) instructions running with
PSR.vm==1 will test the VCPUID[4] register in the VPD. The VMM may maintain a
different VCPUID[4]{63:32} value from the CPUID[4]{63:32} value of the logical
processor on which the virtual processor is running.
If the VMM indicates to a guest that an instruction is not supported by clearing the
corresponding bit in VCPUID[63:32], then guest execution of that instruction, when
a_tf is enabled, will behave the same as it would in implementations that do not
implement that instruction. See
for more information.
If this optimization is disabled or not supported, execution of the test feature (
tf
)
instruction with PSR.vm==1 will test the CPUID[4] register. The VMM must maintain
the same VCPUID[4]{63:32} value as the CPUID[4]{63:32} value of the logical
processor on which the virtual processor is running.
Synchronization is required when this optimization is enabled; see
for
details.
This optimization is not supported on all processor implementations. Software can call
PAL_VP_ENV_INFO to determine the availability of this feature.
When this optimization is enabled, certain VPD state is accessed, as described in
Table 11-16, “Virtual Processor Descriptor (VPD)” on page 2:326
11.7.4.2.10 Interruption Collection and User Mask Optimization
The interruption collection and user mask optimization is enabled by the a_ic_um bit in
the Virtualization Acceleration Control (
vac
) field in the VPD.
When this optimization is enabled and PSR.vm==1, execution of
rsm
and
ssm
instructions
1
with a mask targeting no fields other than the ic and user mask fields will
not intercept to the VMM, unless a fault condition is detected (see
details). The ic field in vpsr and user mask bits in PSR targeted by the mask will be
updated with the new value.
Table 11-42.Impact of clearing VCPUID bits with the a_tf optimization
VCPUID[4] bit
Instructions affected
Behavior when vCPUID[4] is bit is 0
32
clz
Illegal Operation fault
33
mpy4
Illegal Operation fault
mpyshl4
Illegal Operation fault
Table 11-43.Synchronization Requirements for Test Feature Optimization
VPD Resource
Synchronization Required
vcpuid[4]{63:32}
Write
Summary of Contents for ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
Page 1: ......
Page 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 13: ...1 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
Page 57: ...1 46 Volume 1 Part 1 Execution Environment ...
Page 147: ...1 136 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Page 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
Page 230: ......
Page 248: ...236 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 250: ...2 2 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
Page 380: ...2 132 Volume 2 Part 1 Interruptions ...
Page 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Page 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Page 750: ...2 502 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Page 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Page 808: ...2 560 Volume 2 Part 2 Context Management ...
Page 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Page 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
Page 862: ...2 614 Volume 2 Part 2 External Interrupt Architecture ...
Page 870: ...2 622 Volume 2 Part 2 Performance Monitoring Support ...
Page 891: ......
Page 1099: ...3 200 Volume 3 Instruction Reference padd Interruptions Illegal Operation fault ...
Page 1295: ...3 396 Volume 3 Resource and Dependency Semantics ...
Page 1296: ......
Page 1302: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...