{"id":6986,"date":"2020-10-15T10:50:52","date_gmt":"2020-10-15T14:50:52","guid":{"rendered":"https:\/\/www.lpi.org\/xen-virtualization-and-cloud-computing-03-key-features-xen\/"},"modified":"2023-05-10T04:27:51","modified_gmt":"2023-05-10T08:27:51","slug":"xen-virtualization-and-cloud-computing-03-key-features-xen","status":"publish","type":"post","link":"https:\/\/www.lpi.org\/vi\/blog\/2020\/10\/15\/xen-virtualization-and-cloud-computing-03-key-features-xen\/","title":{"rendered":"Xen Virtualization and Cloud Computing #03: Key Features of Xen"},"content":{"rendered":"

The previous articles in this series introduced virtualization and showed how Xen is designed to provide it efficiently. Here we\u2019ll delve into some interesting features and their importance. A larger list can be found at the appropriate project page on features<\/a>. At time of writing this article, the most recent version of Xen Project is 4.13.<\/p>\n

Security-related features<\/h3>\n

The Meltdown and Spectre<\/a> processor vulnerabilities, which exploit complex performance-enhancing features of modern microprocessors, have presented formidable challenges to the developers of operating systems and application. Meltdown and Spectre were officially discovered in January 2018. \u00a0This section describes two enhancements to Xen to mitigate against these difficult vulnerabilities.<\/p>\n

\"Xen
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Meltdown, which affects Intel x86, IBM Power, and some ARM microprocessors, allows a malicious process to read data from any address that is mapped to the current process’s memory space. Effectively, the process can read all memory without permission. The malicious process accomplishes this by finding a timing flaw in the execution of several processor features (such as the cache and pipeline) that are individually secure. At the time of disclosure, this vulnerability affected many products, with impacts on an enormous number of servers and cloud providers. Companies began writing patches to block the Meltdown vulnerability, causing performance losses between 5 and 30 percent.<\/p>\n

Spectre also exploits modern performance features. In modern microprocessors, a digital circuit tries to guess the outcome of a conditional operation such as an \u201cif\u2026else\u201d statement, using information gathered before the execution of the program, and prepares for the most likely result. It. In other words, it tries to guess the way of an if-then-else statement will go before it knows it exactly. The name of this technique is branch prediction. It is an important component of modern CPU architectures such as the x86 and plays a critical role in achieving higher performance. Spectre exploits branch predication system to read arbitrary locations in the allocated memory of a program. This attack can be implemented in a browser using JavaScript, so it is important to keep your browser up to date.<\/p>\n

On March 15, 2018, Intel reported that it will redesign its CPU processors to help protect against Meltdown and Spectre. On October 8, 2018, Intel added firmware to its latest processors to mitigate against these attacks.<\/p>\n

Hypervisor changes to mitigate against Meltdown and Spectre<\/h4>\n

The Xen hypervisor, like other products, was affected by these vulnerabilities, specifically:<\/p>\n