Bringing Virtualization to the x86 Architecture with the Original VMware Workstation
Bringing Virtualization to the x86 Architecture with the Original VMware Workstation
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DOI：
10.1145/2382553.2382554
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发表时间：
2012-11
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影响因子：
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通讯作者：
Edouard Bugnion;Scott Devine;M. Rosenblum;J. Sugerman;E. Wang
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文献类型：
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作者：
Edouard Bugnion;Scott Devine;M. Rosenblum;J. Sugerman;E. Wang
本文介绍了VMware Workstation在1999年将虚拟化引入x86体系结构时所使用的历史背景、技术挑战和主要实现技术。虽然虚拟机监视器（VMM）已经存在了几十年，但它们传统上被设计为单一供应商架构的一部分，并明确支持虚拟化。相比之下，x86架构缺乏虚拟化支持，围绕它的行业已经分解成一个生态系统，不同的供应商控制着计算机，CPU，外围设备，操作系统和应用程序，没有一个要求虚拟化。我们选择独立于这些供应商构建我们的解决方案。因此，VMware Workstation不得不应对以下新挑战：（i）x86架构中缺乏虚拟化支持;（ii）架构本身令人生畏的复杂性;（iii）需要支持广泛的外围设备组合;（iv）需要在现有环境中提供简单的用户体验。这些新的挑战促使我们将著名的虚拟化技术、其他领域的技术和新技术进行了全新的组合。VMware Workstation将托管架构与VMM结合在一起。托管架构实现了简单的用户体验，并提供了广泛的硬件兼容性。VMware Workstation没有将I/O多样性暴露给虚拟机，而是依赖于I/O设备的软件仿真。VMM结合了一个陷阱和模拟直接执行引擎和一个系统级动态二进制翻译器，以有效地虚拟化x86架构并支持大多数商用操作系统。通过依赖x86硬件分段作为保护机制，二进制翻译器可以以接近硬件的速度执行翻译后的代码。二进制翻译器还依赖于部分评估和自适应重新翻译来减少虚拟化的总体开销。这篇文章是基于后见之明撰写的，它分享了我们从构建原始系统及其后来的演变中学到的关键经验教训。
This article describes the historical context, technical challenges, and main implementation techniques used by VMware Workstation to bring virtualization to the x86 architecture in 1999. Although virtual machine monitors (VMMs) had been around for decades, they were traditionally designed as part of monolithic, single-vendor architectures with explicit support for virtualization. In contrast, the x86 architecture lacked virtualization support, and the industry around it had disaggregated into an ecosystem, with different vendors controlling the computers, CPUs, peripherals, operating systems, and applications, none of them asking for virtualization. We chose to build our solution independently of these vendors. As a result, VMware Workstation had to deal with new challenges associated with (i) the lack of virtualization support in the x86 architecture, (ii) the daunting complexity of the architecture itself, (iii) the need to support a broad combination of peripherals, and (iv) the need to offer a simple user experience within existing environments. These new challenges led us to a novel combination of well-known virtualization techniques, techniques from other domains, and new techniques. VMware Workstation combined a hosted architecture with a VMM. The hosted architecture enabled a simple user experience and offered broad hardware compatibility. Rather than exposing I/O diversity to the virtual machines, VMware Workstation also relied on software emulation of I/O devices. The VMM combined a trap-and-emulate direct execution engine with a system-level dynamic binary translator to efficiently virtualize the x86 architecture and support most commodity operating systems. By relying on x86 hardware segmentation as a protection mechanism, the binary translator could execute translated code at near hardware speeds. The binary translator also relied on partial evaluation and adaptive retranslation to reduce the overall overheads of virtualization. Written with the benefit of hindsight, this article shares the key lessons we learned from building the original system and from its later evolution.