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Andrew Cooper
6f1b280876
This is long overdue, and we need to start somewhere. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Jan Beulich <jbeulich@suse.com>
68 lines
2.6 KiB
ReStructuredText
68 lines
2.6 KiB
ReStructuredText
.. SPDX-License-Identifier: CC-BY-4.0
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Glossary
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========
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.. Terms should appear in alphabetical order
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.. glossary::
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control domain
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A :term:`domain`, commonly dom0, with the permission and responsibility
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to create and manage other domains on the system.
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domain
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A domain is Xen's unit of resource ownership, and generally has at the
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minimum some RAM and virtual CPUs.
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The terms :term:`domain` and :term:`guest` are commonly used
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interchangeably, but they mean subtly different things.
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A guest is a single, end user, virtual machine.
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In some cases, e.g. during live migration, one guest will be comprised of
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two domains for a period of time, while it is in transit.
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domid
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The numeric identifier of a running :term:`domain`. It is unique to a
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single instance of Xen, used as the identifier in various APIs, and is
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typically allocated sequentially from 0.
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CET
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Control-flow Enforcement Technology is a facility in x86 CPUs for
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defending against memory safety vulnerabilities. It is formed of two
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independent features:
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* CET-SS, Shadow Stacks, are designed to protect against Return Oriented
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Programming (ROP) attacks.
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* CET-IBT, Indirect Branch Tracking, is designed to protect against Call
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or Jump Oriented Programming (COP/JOP) attacks.
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Intel support CET-SS and CET-IBT from the Tiger Lake (Client, 2020) and
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Sapphire Rapids (Server, 2023) CPUs. AMD support only CET-SS, starting
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with Zen3 (Both client and server, 2020) CPUs.
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guest
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The term 'guest' has two different meanings, depending on context, and
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should not be confused with :term:`domain`.
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When discussing a Xen system as a whole, a 'guest' refer to a virtual
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machine which is the "useful output" of running the system in the first
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place (e.g. an end-user VM). Virtual machines providing system services,
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(e.g. the control and/or hardware domains), are not considered guests in
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this context.
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In the code, "guest context" and "guest state" is considered in terms of
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the CPU architecture, and contrasted against hypervisor context/state.
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In this case, it refers to all code running lower privilege privilege
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level the hypervisor. As such, it covers all domains, including ones
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providing system services.
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hardware domain
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A :term:`domain`, commonly dom0, which shares responsibility with Xen
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about the system as a whole.
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By default it gets all devices, including all disks and network cards, so
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is responsible for multiplexing guest I/O.
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