X86 virtualization

Last updated

x86 virtualization is the use of hardware-assisted virtualization capabilities on an x86/x86-64 CPU.

Contents

In the late 1990s x86 virtualization was achieved by complex software techniques, necessary to compensate for the processor's lack of hardware-assisted virtualization capabilities while attaining reasonable performance. In 2005 and 2006, both Intel (VT-x) and AMD (AMD-V) introduced limited hardware virtualization support that allowed simpler virtualization software but offered very few speed benefits. [1] Greater hardware support, which allowed substantial speed improvements, came with later processor models.

Software-based virtualization

The following discussion focuses only on virtualization of the x86 architecture protected mode.

In protected mode the operating system kernel runs at a higher privilege such as ring 0, and applications at a lower privilege such as ring 3.[ citation needed ] In software-based virtualization, a host OS has direct access to hardware while the guest OSs have limited access to hardware, just like any other application of the host OS. One approach used in x86 software-based virtualization to overcome this limitation is called ring deprivileging, which involves running the guest OS at a ring higher (lesser privileged) than 0. [2]

Three techniques made virtualization of protected mode possible:

These techniques incur some performance overhead due to lack of MMU virtualization support, as compared to a VM running on a natively virtualizable architecture such as the IBM System/370. [4] : 10  [9] : 17 and 21 

On traditional mainframes, the classic type 1 hypervisor was self-standing and did not depend on any operating system or run any user applications itself. In contrast, the first x86 virtualization products were aimed at workstation computers, and ran a guest OS inside a host OS by embedding the hypervisor in a kernel module that ran under the host OS (type 2 hypervisor). [8]

There has been some controversy whether the x86 architecture with no hardware assistance is virtualizable as described by Popek and Goldberg. VMware researchers pointed out in a 2006 ASPLOS paper that the above techniques made the x86 platform virtualizable in the sense of meeting the three criteria of Popek and Goldberg, albeit not by the classic trap-and-emulate technique. [4] : 2–3 

A different route was taken by other systems like Denali, L4, and Xen, known as paravirtualization, which involves porting operating systems to run on the resulting virtual machine, which does not implement the parts of the actual x86 instruction set that are hard to virtualize. The paravirtualized I/O has significant performance benefits as demonstrated in the original SOSP'03 Xen paper. [10]

The initial version of x86-64 (AMD64) did not allow for a software-only full virtualization due to the lack of segmentation support in long mode, which made the protection of the hypervisor's memory impossible, in particular, the protection of the trap handler that runs in the guest kernel address space. [11] [12] : 11 and 20  Revision D and later 64-bit AMD processors (as a rule of thumb, those manufactured in 90 nm or less) added basic support for segmentation in long mode, making it possible to run 64-bit guests in 64-bit hosts via binary translation. Intel did not add segmentation support to its x86-64 implementation (Intel 64), making 64-bit software-only virtualization impossible on Intel CPUs, but Intel VT-x support makes 64-bit hardware assisted virtualization possible on the Intel platform. [13] [14] : 4 

On some platforms, it is possible to run a 64-bit guest on a 32-bit host OS if the underlying processor is 64-bit and supports the necessary virtualization extensions.

Hardware-assisted virtualization

In 2005 and 2006, Intel and AMD (working independently) created new processor extensions to the x86 architecture. The first generation of x86 hardware virtualization addressed the issue of privileged instructions. The issue of low performance of virtualized system memory was addressed with MMU virtualization that was added to the chipset later.

Central processing unit

Virtual 8086 mode

Based on painful experiences with the 80286 protected mode, which by itself was not suitable enough to run concurrent DOS applications well, Intel introduced the virtual 8086 mode in their 80386 chip, which offered virtualized 8086 processors on the 386 and later chips. Hardware support for virtualizing the protected mode itself, however, became available 20 years later. [15]

AMD virtualization (AMD-V)

AMD Phenom Die AMD Phenom die equalized.png
AMD Phenom Die

AMD developed its first generation virtualization extensions under the code name "Pacifica", and initially published them as AMD Secure Virtual Machine (SVM), [16] but later marketed them under the trademark AMD Virtualization, abbreviated AMD-V.

On May 23, 2006, AMD released the Athlon 64 ("Orleans"), the Athlon 64 X2 ("Windsor") and the Athlon 64 FX ("Windsor") as the first AMD processors to support this technology.

AMD-V capability also features on the Athlon 64 and Athlon 64 X2 family of processors with revisions "F" or "G" on socket AM2, Turion 64 X2, and Opteron 2nd generation [17] and third-generation, [18] Phenom and Phenom II processors. The APU Fusion processors support AMD-V. AMD-V is not supported by any Socket 939 processors. The only Sempron processors which support it are APUs and Huron, Regor, Sargas desktop CPUs.

AMD Opteron CPUs beginning with the Family 0x10 Barcelona line, and Phenom II CPUs, support a second generation hardware virtualization technology called Rapid Virtualization Indexing (formerly known as Nested Page Tables during its development), later adopted by Intel as Extended Page Tables (EPT).

As of 2019, all Zen-based AMD processors support AMD-V.

The CPU flag for AMD-V is "svm". This may be checked in BSD derivatives via dmesg or sysctl and in Linux via /proc/cpuinfo . [19] Instructions in AMD-V include VMRUN, VMLOAD, VMSAVE, CLGI, VMMCALL, INVLPGA, SKINIT, and STGI.

With some motherboards, users must enable AMD SVM feature in the BIOS setup before applications can make use of it. [20]

Intel virtualization (VT-x)

Intel Core i7 (Bloomfield) CPU Intel Core i7-940 bottom.jpg
Intel Core i7 (Bloomfield) CPU

Previously codenamed "Vanderpool", VT-x represents Intel's technology for virtualization on the x86 platform. On November 13, 2005, Intel released two models of Pentium 4 (Model 662 and 672) as the first Intel processors to support VT-x. The CPU flag for VT-x capability is "vmx"; in Linux, this can be checked via /proc/cpuinfo, or in macOS via sysctl machdep.cpu.features. [19]

"VMX" stands for Virtual Machine Extensions, which adds 13 new instructions: VMPTRLD, VMPTRST, VMCLEAR, VMREAD, VMWRITE, VMCALL, VMLAUNCH, VMRESUME, VMXOFF, VMXON, INVEPT, INVVPID, and VMFUNC. [21] These instructions permit entering and exiting a virtual execution mode where the guest OS perceives itself as running with full privilege (ring 0), but the host OS remains protected.

As of 2015, almost all newer server, desktop and mobile Intel processors support VT-x, with some of the Intel Atom processors as the primary exception. [22] With some motherboards, users must enable Intel's VT-x feature in the BIOS setup before applications can make use of it. [23]

Intel started to include Extended Page Tables (EPT), [24] a technology for page-table virtualization, [25] since the Nehalem architecture, [26] [27] released in 2008. In 2010, Westmere added support for launching the logical processor directly in real mode  – a feature called "unrestricted guest", which requires EPT to work. [28] [29]

Since the Haswell microarchitecture (announced in 2013), Intel started to include VMCS shadowing as a technology that accelerates nested virtualization of VMMs. [30] The virtual machine control structure (VMCS) is a data structure in memory that exists exactly once per VM, while it is managed by the VMM. With every change of the execution context between different VMs, the VMCS is restored for the current VM, defining the state of the VM's virtual processor. [31] As soon as more than one VMM or nested VMMs are used, a problem appears in a way similar to what required shadow page table management to be invented, as described above. In such cases, VMCS needs to be shadowed multiple times (in case of nesting) and partially implemented in software in case there is no hardware support by the processor. To make shadow VMCS handling more efficient, Intel implemented hardware support for VMCS shadowing. [32]

VIA virtualization (VIA VT)

VIA Nano 3000 Series Processors and higher support VIA VT virtualization technology compatible with Intel VT-x. [33] EPT is present in Zhaoxin ZX-C, a descendant of VIA QuadCore-E & Eden X4 similar to Nano C4350AL. [34]

Interrupt virtualization (AMD AVIC and Intel APICv)

In 2012, AMD announced their Advanced Virtual Interrupt Controller (AVIC) targeting interrupt overhead reduction in virtualization environments. [35] This technology, as announced, does not support x2APIC. [36] In 2016, AVIC is available on the AMD family 15h models 6Xh (Carrizo) processors and newer. [37]

Also in 2012, Intel announced a similar technology for interrupt and APIC virtualization, which did not have a brand name at its announcement time. [38] Later, it was branded as APIC virtualization (APICv) [39] and it became commercially available in the Ivy Bridge EP series of Intel CPUs, which is sold as Xeon E5-26xx v2 (launched in late 2013) and as Xeon E5-46xx v2 (launched in early 2014). [40]

Graphics processing unit

Graphics virtualization is not part of the x86 architecture. Intel Graphics Virtualization Technology (GVT) provides graphics virtualization as part of more recent Gen graphics architectures. Although AMD APUs implement the x86-64 instruction set, they implement AMD's own graphics architectures (TeraScale, GCN and RDNA) which do not support graphics virtualization.[ citation needed ] Larrabee was the only graphics microarchitecture based on x86, but it likely did not include support for graphics virtualization.

Chipset

Memory and I/O virtualization is performed by the chipset. [41] Typically these features must be enabled by the BIOS, which must be able to support them and also be set to use them.

I/O MMU virtualization (AMD-Vi and Intel VT-d)

A Linux kernel log showing AMD-Vi information AMD-Vi boot log screenshot.png
A Linux kernel log showing AMD-Vi information

An input/output memory management unit (IOMMU) allows guest virtual machines to directly use peripheral devices, such as Ethernet, accelerated graphics cards, and hard-drive controllers, through DMA and interrupt remapping. This is sometimes called PCI passthrough. [42]

An IOMMU also allows operating systems to eliminate bounce buffers needed to allow themselves to communicate with peripheral devices whose memory address spaces are smaller than the operating system's memory address space, by using memory address translation. At the same time, an IOMMU also allows operating systems and hypervisors to prevent buggy or malicious hardware from compromising memory security.

Both AMD and Intel have released their IOMMU specifications:

  • AMD's I/O Virtualization Technology, "AMD-Vi", originally called "IOMMU" [43]
  • Intel's "Virtualization Technology for Directed I/O" (VT-d), [44] included in most high-end (but not all) newer Intel processors since the Core 2 architecture. [45]

In addition to the CPU support, both motherboard chipset and system firmware (BIOS or UEFI) need to fully support the IOMMU I/O virtualization functionality for it to be usable. Only the PCI or PCI Express devices supporting function level reset (FLR) can be virtualized this way, as it is required for reassigning various device functions between virtual machines. [46] [47] If a device to be assigned does not support Message Signaled Interrupts (MSI), it must not share interrupt lines with other devices for the assignment to be possible. [48] All conventional PCI devices routed behind a PCI/PCI-X-to-PCI Express bridge can be assigned to a guest virtual machine only all at once; PCI Express devices have no such restriction.

Network virtualization (VT-c)

  • Intel's "Virtualization Technology for Connectivity" (VT-c). [49]
PCI-SIG Single Root I/O Virtualization (SR-IOV)

PCI-SIG Single Root I/O Virtualization (SR-IOV) provides a set of general (non-x86 specific) I/O virtualization methods based on PCI Express (PCIe) native hardware, as standardized by PCI-SIG: [50]

  • Address translation services (ATS) supports native IOV across PCI Express via address translation. It requires support for new transactions to configure such translations.
  • Single-root IOV (SR-IOV or SRIOV) supports native IOV in existing single-root complex PCI Express topologies. It requires support for new device capabilities to configure multiple virtualized configuration spaces. [51]
  • Multi-root IOV (MR-IOV) supports native IOV in new topologies (for example, blade servers) by building on SR-IOV to provide multiple root complexes which share a common PCI Express hierarchy.

In SR-IOV, the most common of these, a host VMM configures supported devices to create and allocate virtual "shadows" of their configuration spaces so that virtual machine guests can directly configure and access such "shadow" device resources. [52] With SR-IOV enabled, virtualized network interfaces are directly accessible to the guests, [53] avoiding involvement of the VMM and resulting in high overall performance; [51] for example, SR-IOV achieves over 95% of the bare metal network bandwidth in NASA's virtualized datacenter [54] and in the Amazon Public Cloud. [55] [56]

See also

Related Research Articles

x86-64 Type of instruction set which is a 64-bit version of the x86 instruction set

x86-64 is a 64-bit version of the x86 instruction set, first released in 1999. It introduced two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging mode.

<span class="mw-page-title-main">Xen</span> Type-1 hypervisor

Xen is a free and open-source type-1 hypervisor, providing services that allow multiple computer operating systems to execute on the same computer hardware concurrently. It was originally developed by the University of Cambridge Computer Laboratory and is now being developed by the Linux Foundation with support from Intel, Citrix, Arm Ltd, Huawei, AWS, Alibaba Cloud, AMD, Bitdefender and epam.

In the 80386 microprocessor and later, virtual 8086 mode allows the execution of real mode applications that are incapable of running directly in protected mode while the processor is running a protected mode operating system. It is a hardware virtualization technique that allowed multiple 8086 processors to be emulated by the 386 chip. It emerged from the painful experiences with the 80286 protected mode, which by itself was not suitable to run concurrent real-mode applications well. John Crawford developed the Virtual Mode bit at the register set, paving the way to this environment.

In computing, paravirtualization or para-virtualization is a virtualization technique that presents a software interface to the virtual machines which is similar, yet not identical, to the underlying hardware–software interface.

<span class="mw-page-title-main">QEMU</span> Free virtualization and emulation software

QEMU is a free and open-source emulator. It emulates the machine's processor through dynamic binary translation and provides a set of different hardware and device models for the machine, enabling it to run a variety of guest operating systems. It can interoperate with Kernel-based Virtual Machine (KVM) to run virtual machines at near-native speed. QEMU can also do emulation for user-level processes, allowing applications compiled for one architecture to run on another.

Platform virtualization software, specifically emulators and hypervisors, are software packages that emulate the whole physical computer machine, often providing multiple virtual machines on one physical platform. The table below compares basic information about platform virtualization hypervisors.

Microsoft Virtual Server was a virtualization solution that facilitated the creation of virtual machines on the Windows XP, Windows Vista and Windows Server 2003 operating systems. Originally developed by Connectix, it was acquired by Microsoft prior to release. Virtual PC is Microsoft's related desktop virtualization software package.

In computing, Intel's Advanced Programmable Interrupt Controller (APIC) is a family of interrupt controllers. As its name suggests, the APIC is more advanced than Intel's 8259 Programmable Interrupt Controller (PIC), particularly enabling the construction of multiprocessor systems. It is one of several architectural designs intended to solve interrupt routing efficiency issues in multiprocessor computer systems.

<span class="mw-page-title-main">Protection ring</span> Layer of protection in computer systems

In computer science, hierarchical protection domains, often called protection rings, are mechanisms to protect data and functionality from faults and malicious behavior.

In computing, hardware-assisted virtualization is a platform virtualization approach that enables efficient full virtualization using help from hardware capabilities, primarily from the host processors. A full virtualization is used to emulate a complete hardware environment, or virtual machine, in which an unmodified guest operating system effectively executes in complete isolation. Hardware-assisted virtualization was added to x86 processors in 2005, 2006 and 2010 (respectively).

<span class="mw-page-title-main">Input–output memory management unit</span>

In computing, an input–output memory management unit (IOMMU) is a memory management unit (MMU) connecting a direct-memory-access–capable (DMA-capable) I/O bus to the main memory. Like a traditional MMU, which translates CPU-visible virtual addresses to physical addresses, the IOMMU maps device-visible virtual addresses to physical addresses. Some units also provide memory protection from faulty or malicious devices.

The following is a timeline of virtualization development. In computing, virtualization is the use of a computer to simulate another computer. Through virtualization, a host simulates a guest by exposing virtual hardware devices, which may be done through software or by allowing access to a physical device connected to the machine.

<span class="mw-page-title-main">Full virtualization</span> Computing technique involving instances of an environment

In computer science, full virtualization (fv) employs techniques used to create instances of an environment, as opposed to simulation, which models the environment; or emulation, which replicates the target environment such as certain kinds of virtual machine environments. Full virtualization requires that every salient feature of the hardware be reflected into one of several virtual machines – including the full instruction set, input/output operations, interrupts, memory access, and whatever other elements are used by the software that runs on the bare machine, and that is intended to run in a virtual machine. In such an environment, any software capable of execution on the raw hardware can be run in the virtual machine and, in particular, any operating systems. The obvious test of full virtualization is whether an operating system intended for stand-alone use can successfully run inside a virtual machine. This is a modern technique developed in late 1990s and is different from simulation and emulation.

<span class="mw-page-title-main">Kernel-based Virtual Machine</span> Virtualization module in the Linux kernel

Kernel-based Virtual Machine (KVM) is a free and open-source virtualization module in the Linux kernel that allows the kernel to function as a hypervisor. It was merged into the mainline Linux kernel in version 2.6.20, which was released on February 5, 2007. KVM requires a processor with hardware virtualization extensions, such as Intel VT or AMD-V. KVM has also been ported to other operating systems such as FreeBSD and illumos in the form of loadable kernel modules.

<span class="mw-page-title-main">VirtualBox</span> Open-source x86 virtualization application

Oracle VM VirtualBox is a type-2 hypervisor for x86 virtualization developed by Oracle Corporation. VirtualBox was originally created by InnoTek Systemberatung GmbH, which was acquired by Sun Microsystems in 2008, which was in turn acquired by Oracle in 2010.

Hardware virtualization is the virtualization of computers as complete hardware platforms, certain logical abstractions of their componentry, or only the functionality required to run various operating systems. Virtualization hides the physical characteristics of a computing platform from the users, presenting instead an abstract computing platform. At its origins, the software that controlled virtualization was called a "control program", but the terms "hypervisor" or "virtual machine monitor" became preferred over time.

<span class="mw-page-title-main">Hyper-V</span> Native hypervisor by Microsoft

Microsoft Hyper-V, codenamed Viridian, and briefly known before its release as Windows Server Virtualization, is a native hypervisor; it can create virtual machines on x86-64 systems running Windows. Starting with Windows 8, Hyper-V superseded Windows Virtual PC as the hardware virtualization component of the client editions of Windows NT. A server computer running Hyper-V can be configured to expose individual virtual machines to one or more networks. Hyper-V was first released with Windows Server 2008, and has been available without additional charge since Windows Server 2012 and Windows 8. A standalone Windows Hyper-V Server is free, but has a command-line interface only. The last version of free Hyper-V Server is Hyper-V Server 2019, which is based on Windows Server 2019.

Second Level Address Translation (SLAT), also known as nested paging, is a hardware-assisted virtualization technology which makes it possible to avoid the overhead associated with software-managed shadow page tables.

<span class="mw-page-title-main">Qubes OS</span> Security-focused Linux-based operating system

Qubes OS is a security-focused desktop operating system that aims to provide security through isolation. Virtualization is performed by Xen, and user environments can be based on the officially supported Fedora or Debian, or with the community supported Whonix, Ubuntu, Arch Linux, CentOS, or Gentoo.

GPU virtualization refers to technologies that allow the use of a GPU to accelerate graphics or GPGPU applications running on a virtual machine. GPU virtualization is used in various applications such as desktop virtualization, cloud gaming and computational science.

References

  1. ↑ A Comparison of Software and Hardware Techniques for x86 Virtualization, Keith Adams and Ole Agesen, VMware, ASPLOS’06 October 21–25, 2006, San Jose, California, USA Archived 2010-08-20 at the Wayback Machine "Surprisingly, we find that the first-generation hardware support rarely offers performance advantages over existing software techniques. We ascribe this situation to high VMM/guest transition costs and a rigid programming model that leaves little room for software flexibility in managing either the frequency or cost of these transitions.
  2. ↑ "Intel Virtualization Technology Processor Virtualization Extensions and Intel Trusted execution Technology" (PDF). Intel.com. 2007. Archived (PDF) from the original on 2015-05-21. Retrieved 2016-12-12.
  3. ↑ "USENIX Technical Program - Abstract - Security Symposium - 2000". Usenix.org. 2002-01-29. Archived from the original on 2010-06-10. Retrieved 2010-05-02.
  4. 1 2 3 4 5 "A Comparison of Software and Hardware Techniques for x86 Virtualization" (PDF). VMware. Archived (PDF) from the original on 20 August 2010. Retrieved 8 September 2010.
  5. 1 2 U.S. Patent 6,397,242
  6. ↑ U.S. Patent 6,704,925
  7. ↑ "Virtualization: architectural considerations and other evaluation criteria" (PDF). VMware. Archived (PDF) from the original on 6 February 2011. Retrieved 8 September 2010.
  8. 1 2 U.S. Patent 6,496,847
  9. ↑ "VMware and Hardware Assist Technology" (PDF). Archived (PDF) from the original on 2011-07-17. Retrieved 2010-09-08.
  10. ↑ "Xen and the Art of Virtualization" (PDF). Archived (PDF) from the original on 2014-09-29.
  11. ↑ "How retiring segmentation in AMD64 long mode broke VMware". Pagetable.com. 2006-11-09. Archived from the original on 2011-07-18. Retrieved 2010-05-02.
  12. ↑ "VMware and CPU Virtualization Technology" (PDF). VMware. Archived (PDF) from the original on 2011-07-17. Retrieved 2010-09-08.
  13. ↑ "VMware KB: Hardware and firmware requirements for 64bit guest operating systems". Kb.vmware.com. Archived from the original on 2010-04-19. Retrieved 2010-05-02.
  14. ↑ "Software and Hardware Techniques for x86 Virtualization" (PDF). Archived from the original (PDF) on 2010-01-05. Retrieved 2010-05-02.
  15. ↑ Yager, Tom (2004-11-05). "Sending software to do hardware's job | Hardware - InfoWorld". Images.infoworld.com. Archived from the original on 2014-10-18. Retrieved 2014-01-08.
  16. ↑ "33047_SecureVirtualMachineManual_3-0.book" (PDF). Archived (PDF) from the original on 2012-03-05. Retrieved 2010-05-02.
  17. ↑ "What are the main differences between Second-Generation AMD Opteron processors and first-generation AMD Opteron processors?". amd.com. Archived from the original on April 15, 2009. Retrieved 2012-02-04.
  18. ↑ "What virtualization enhancements do Quad-Core AMD Opteron processors feature?". amd.com. Archived from the original on April 16, 2009. Retrieved 2012-02-04.
  19. 1 2 To see if your processor supports hardware virtualization Archived 2012-11-25 at the Wayback Machine Intel 2012.
  20. ↑ "How to enable Intel VTx and AMD SVM?". Support. QNAP Systems, Inc. Archived from the original on 2018-03-07. Retrieved 2020-12-23.
  21. ↑ INTEL (October 2019). "Intel® 64 and IA-32 Architectures Software Developer's Manual". intel.com. Intel Corporation. Retrieved 2020-01-04.
  22. ↑ "Intel Virtualization Technology List". Ark.intel.com. Archived from the original on 2010-10-27. Retrieved 2010-05-02.
  23. ↑ "Windows Virtual PC: Configure BIOS". Microsoft. Archived from the original on 2010-09-06. Retrieved 2010-09-08.
  24. ↑ Neiger, Gil; A. Santoni; F. Leung; D. Rodgers; R. Uhlig (2006). "Intel Virtualization Technology: Hardware Support for Efficient Processor Virtualization" (PDF). Intel Technology Journal. Intel. 10 (3): 167–178. doi:10.1535/itj.1003.01. Archived from the original (PDF) on 2012-09-25. Retrieved 2008-07-06.
  25. ↑ Gillespie, Matt (2007-11-12). "Best Practices for Paravirtualization Enhancements from Intel Virtualization Technology: EPT and VT-d". Intel Software Network. Intel. Archived from the original on 2008-12-26. Retrieved 2008-07-06.
  26. ↑ "First the Tick, Now the Tock: Next Generation Intel Microarchitecture (Nehalem)" (PDF) (Press release). Intel. Archived (PDF) from the original on 2009-01-26. Retrieved 2008-07-06.
  27. ↑ "Technology Brief: Intel Microarchitecture Nehalem Virtualization Technology" (PDF). Intel. 2009-03-25. Archived (PDF) from the original on 2011-06-07. Retrieved 2009-11-03.
  28. ↑ "Intel added unrestricted guest mode on Westmere micro-architecture and later Intel CPUs, it uses EPT to translate guest physical address access to host physical address. With this mode, VMEnter without enable paging is allowed."
  29. ↑ "If the “unrestricted guest” VM-execution control is 1, the “enable EPT” VM-execution control must also be 1"
  30. ↑ "4th-Gen Intel Core vPro Processors with Intel VMCS Shadowing" (PDF). Intel. 2013. Retrieved 2014-12-16.
  31. ↑ Understanding Intel Virtualization Technology (VT). Archived September 8, 2014, at the Wayback Machine Retrieved 2014-09-01
  32. ↑ The 'what, where and why' of VMCS shadowing. Archived 2014-09-03 at the Wayback Machine Retrieved 2014-09-01
  33. ↑ VIA Introduces New VIA Nano 3000 Series Processors Archived January 22, 2013, at the Wayback Machine
  34. ↑ "Notebook Solution: Kaixian ZX-C Processor + VX11PH Chipset" (PDF).
  35. ↑ Wei Huang, Introduction of AMD Advanced Virtual Interrupt Controller Archived 2014-07-14 at the Wayback Machine , XenSummit 2012
  36. ↑ Jörg Rödel (August 2012). "Next-generation Interrupt Virtualization for KVM" (PDF). AMD. Archived (PDF) from the original on 2016-03-04. Retrieved 2014-07-12.
  37. ↑ "[Xen-devel][RFC PATCH 0/9] Introduce AMD SVM AVIC". www.mail-archive.com. Archived from the original on 2 February 2017. Retrieved 4 May 2018.
  38. ↑ Jun Nakajimaa (2012-12-13). "Reviewing Unused and New Features for Interrupt/APIC Virtualization" (PDF). Intel. Archived (PDF) from the original on 2015-04-21. Retrieved 2014-07-12.
  39. ↑ Khang Nguyen (2013-12-17). "APIC Virtualization Performance Testing and Iozone". software.intel.com. Archived from the original on 2014-07-14. Retrieved 2014-07-12.
  40. ↑ "Product Brief Intel Xeon Processor E5-4600 v2 Product Family" (PDF). Intel. 2014-03-14. Archived (PDF) from the original on 2014-07-14. Retrieved 2014-07-12.
  41. ↑ "Intel platform hardware support for I/O virtualization". Intel.com. 2006-08-10. Archived from the original on 2007-01-20. Retrieved 2012-02-04.
  42. ↑ "Linux virtualization and PCI passthrough". IBM. Archived from the original on 1 November 2009. Retrieved 10 November 2010.
  43. ↑ "AMD I/O Virtualization Technology (IOMMU) Specification Revision 1.26" (PDF). Archived (PDF) from the original on 2011-01-24. Retrieved 2011-05-24.
  44. ↑ "Intel Virtualization Technology for Directed I/O (VT-d) Architecture Specification". Archived from the original on 2013-04-03. Retrieved 2012-02-04.
  45. ↑ "Intel Virtualization Technology for Directed I/O (VT-d) Supported CPU List". Ark.intel.com. Archived from the original on 2010-10-27. Retrieved 2012-02-04.
  46. ↑ "PCI-SIG Engineering Change Notice: Function Level Reset (FLR)" (PDF). pcisig.com. 2006-06-27. Archived (PDF) from the original on 2016-03-04. Retrieved 2014-01-10.
  47. ↑ "Xen VT-d". xen.org. 2013-06-06. Archived from the original on 2014-02-09. Retrieved 2014-01-10.
  48. ↑ "How to assign devices with VT-d in KVM". linux-kvm.org. 2014-04-23. Archived from the original on 2015-03-10. Retrieved 2015-03-05.
  49. ↑ "Intel Virtualization Technology for Connectivity (VT-c)" (PDF). Intel.com. Archived (PDF) from the original on 2016-02-22. Retrieved 2018-02-14.
  50. ↑ "PCI-SIG I/O Virtualization (IOV) Specifications". Pcisig.com. 2011-03-31. Archived from the original on 2012-01-15. Retrieved 2012-02-04.
  51. 1 2 "Intel Look Inside: Intel Ethernet" (PDF). Intel. November 27, 2014. p. 104. Archived from the original (PDF) on March 4, 2016. Retrieved March 26, 2015.
  52. ↑ Yaozu Dong; Zhao Yu; Greg Rose (2008). "SR-IOV Networking in Xen: Architecture, Design and Implementation". usenix.org. USENIX. Archived from the original on 2014-01-09. Retrieved 2014-01-10.
  53. ↑ Patrick Kutch; Brian Johnson; Greg Rose (September 2011). "An Introduction to Intel Flexible Port Partitioning Using SR-IOV Technology" (PDF). Intel. Archived from the original (PDF) on August 7, 2015. Retrieved September 24, 2015.
  54. ↑ "NASA's Flexible Cloud Fabric: Moving Cluster Applications to the Cloud" (PDF). Intel. Archived from the original (PDF) on 2012-12-22. Retrieved 2014-01-08.
  55. ↑ "Enhanced Networking in the AWS Cloud". Scalable Logic. 2013-12-31. Archived from the original on 2014-01-09. Retrieved 2014-01-08.
  56. ↑ "Enhanced Networking in the AWS Cloud - Part 2". Scalable Logic. 2013-12-31. Archived from the original on 2014-01-10. Retrieved 2014-01-08.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.