Intel CM8063501287403 Manual Do Utilizador

 

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Intel® Xeon® Processor E5-1600 v2/E5-2600 v2 Product Families 

Datasheet Volume One of Two

The processor core supports the following Intel VT-x features:

• Extended Page Tables (EPT)

— hardware assisted page table virtualization
— eliminates VM exits from guest OS to the VMM for shadow page-table 

maintenance

• Virtual Processor IDs (VPID)

— Ability to assign a VM ID to tag processor core hardware structures (for 

example, TLBs) 

— This avoids flushes on VM transitions to give a lower-cost VM transition time 

and an overall reduction in virtualization overhead.

• Guest Preemption Timer

— Mechanism for a VMM to preempt the execution of a guest OS after an amount 

of time specified by the VMM. The VMM sets a timer value before entering a 

guest

— The feature aids VMM developers in flexibility and Quality of Service (QoS) 

guarantees

• Descriptor-Table Exiting

— Descriptor-table exiting allows a VMM to protect a guest OS from internal 

(malicious software based) attack by preventing relocation of key system data 

structures like IDT (interrupt descriptor table), GDT (global descriptor table), 

LDT (local descriptor table), and TSS (task segment selector). 

— A VMM using this feature can intercept (by a VM exit) attempts to  

relocate these data structures and prevent them from being tampered by 

malicious software.

• Pause Loop Exiting (PLE)

— PLE aims to improve virtualization performance and enhance the scaling of 

virtual machines with multiple virtual processors

— PLE attempts to detect lock-holder preemption in a VM and helps the VMM to 

make better scheduling decisions

• APIC Virtualization (APICv) 

— APICv adds hardware support in the processor to reduce the overhead of virtual 

interrupt processing (APIC accesses and interrupt delivery). This benefits 

mostly interrupt intensive workloads.

— In a virtualized environment the virtual machine manager (VMM) must emulate 

nearly all guest OS accesses to the advanced programmable interrupt 

controller (APIC) registers which requires “VM exits” (time-consuming 

transitions to the VMM for emulation and back). These exits are a major source 

of overhead in a virtual environment. Intel's Advanced Programmable Interrupt 

Controller virtualization (APICv) reduces the number of exits by redirecting 

most guest OS APIC reads/writes to a virtual-APIC page to allow most reads to 

occur without VM exits. 

The key Intel VT-d objectives are domain-based isolation and hardware-based 
virtualization. A domain can be abstractly defined as an isolated environment in a 

platform to which a subset of host physical memory is allocated. Virtualization allows 

for the creation of one or more partitions on a single system. This could be multiple