From patchwork Fri Sep 27 09:00:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 11164091 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 582AB924 for ; Fri, 27 Sep 2019 09:02:16 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3DB3F2146E for ; Fri, 27 Sep 2019 09:02:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3DB3F2146E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1iDm7R-0005Ks-QI; Fri, 27 Sep 2019 09:00:53 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1iDm7R-0005KD-6u for xen-devel@lists.xenproject.org; Fri, 27 Sep 2019 09:00:53 +0000 X-Inumbo-ID: 4e2a9b42-e105-11e9-b588-bc764e2007e4 Received: from mx1.suse.de (unknown [195.135.220.15]) by localhost (Halon) with ESMTPS id 4e2a9b42-e105-11e9-b588-bc764e2007e4; Fri, 27 Sep 2019 09:00:51 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id E52A9AF97; Fri, 27 Sep 2019 09:00:50 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org Date: Fri, 27 Sep 2019 11:00:43 +0200 Message-Id: <20190927090048.28872-2-jgross@suse.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190927090048.28872-1-jgross@suse.com> References: <20190927090048.28872-1-jgross@suse.com> Subject: [Xen-devel] [PATCH v1 1/6] docs: add feature document for Xen hypervisor sysfs-like support X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Stefano Stabellini , Wei Liu , Konrad Rzeszutek Wilk , George Dunlap , Andrew Cooper , Ian Jackson , Tim Deegan , Julien Grall , Jan Beulich MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" On the 2019 Xen developer summit there was agreement that the Xen hypervisor should gain support for a hierarchical name-value store similar to the Linux kernel's sysfs. In the beginning there should only be basic support: entries can be added from the hypervisor itself only, there is a simple hypercall interface to read the data. Add a feature document for setting the base of a discussion regarding the desired functionality and the entries to add. Signed-off-by: Juergen Gross --- V1: - remove the "--" prefixes of the sub-commands of the user tool (Jan Beulich) - rename xenfs to xenhypfs (Jan Beulich) - add "tree" and "write" options to user tool --- docs/features/hypervisorfs.pandoc | 119 ++++++++++++++++++++++++++++++++++++++ docs/misc/hypfs-paths.pandoc | 55 ++++++++++++++++++ 2 files changed, 174 insertions(+) create mode 100644 docs/features/hypervisorfs.pandoc create mode 100644 docs/misc/hypfs-paths.pandoc diff --git a/docs/features/hypervisorfs.pandoc b/docs/features/hypervisorfs.pandoc new file mode 100644 index 0000000000..3155cee7d3 --- /dev/null +++ b/docs/features/hypervisorfs.pandoc @@ -0,0 +1,119 @@ +% Hypervisor FS +% Revision 1 + +\clearpage + +# Basics +---------------- --------------------- + Status: e.g. **Supported** + + Architectures: all + + Components: Hypervisor, toolstack +---------------- --------------------- + +# Overview + +The Hypervisor FS is a hierarchical name-value store for reporting +information to guests, especially dom0. It is similar to the Linux +kernel's sysfs, but without the functionality to directly alter +entries values. Entries and directories are created by the hypervisor, +while the toolstack is able to use a hypercall to query the entry +values. + +# User details + +With: + + xenhypfs ls + +the user can list the entries of a specific path of the FS. Using: + + xenhypfs cat + +the content of an entry can be retrieved. Using: + + xenhypfs write + +a writable entry can be modified. With: + + xenhypfs tree + +the complete Hypervisor FS entry tree can be printed. + +The FS structure is: + + / + buildinfo/ directory containing build-time data + config contents of .config file used to build Xen + cpu-bugs/ x86: directory of cpu bug information + l1tf "Vulnerable" or "Not vulnerable" + mds "Vulnerable" or "Not vulnerable" + meltdown "Vulnerable" or "Not vulnerable" + spec-store-bypass "Vulnerable" or "Not vulnerable" + spectre-v1 "Vulnerable" or "Not vulnerable" + spectre-v2 "Vulnerable" or "Not vulnerable" + mitigations/ directory of mitigation settings + bti-thunk "N/A", "RETPOLINE", "LFENCE" or "JMP" + spec-ctrl "No", "IBRS+" or IBRS-" + ibpb "No" or "Yes" + l1d-flush "No" or "Yes" + md-clear "No" or "VERW" + l1tf-barrier "No" or "Yes" + active-hvm/ directory for mitigations active in hvm doamins + msr-spec-ctrl "No" or "Yes" + rsb "No" or "Yes" + eager-fpu "No" or "Yes" + md-clear "No" or "Yes" + active-pv/ directory for mitigations active in pv doamins + msr-spec-ctrl "No" or "Yes" + rsb "No" or "Yes" + eager-fpu "No" or "Yes" + md-clear "No" or "Yes" + xpti "No" or list of "dom0", "domU", "PCID on" + l1tf-shadow "No" or list of "dom0", "domU" + parameters/ directory with hypervisor parameter values + (boot/runtime parameters) + +# Technical details + +Access to the hypervisor filesystem is done via the stable new hypercall +__HYPERVISOR_filesystem_op. + +* hypercall interface specification + * `xen/include/public/filesystem.h` +* hypervisor internal files + * `xen/include/xen/filesystem.h` + * `xen/common/filesystem.c` +* `libxenhypfs` + * `tools/libs/libxenhypfs/*` +* `xenhypfs` + * `tools/misc/xenhypfs.c` +* path documentation + * `docs/misc/hypfs-paths.pandoc` + +# Testing + +Any new parameters or hardware mitigations should be verified to show up +correctly in the filesystem. + +# Areas for improvement + +* More detailed access rights +* Entries per domain and/or per cpupool + +# Known issues + +* None + +# References + +* None + +# History + +------------------------------------------------------------------------ +Date Revision Version Notes +---------- -------- -------- ------------------------------------------- +2019-09-18 1 Xen 4.13 Document written +---------- -------- -------- ------------------------------------------- diff --git a/docs/misc/hypfs-paths.pandoc b/docs/misc/hypfs-paths.pandoc new file mode 100644 index 0000000000..2fe5455e6f --- /dev/null +++ b/docs/misc/hypfs-paths.pandoc @@ -0,0 +1,55 @@ +# Xenhypfs Paths + +This document attempts to define all the paths which are available +in the Xen hypervisor file system (hypfs). + +The hypervisor file system can be accessed via the xenhypfs tool. + +## Notation + +The hypervisor file system is similar to the Linux kernel's sysfs. +In this document directories are always specified with a trailing "/". + +The following notation conventions apply: + + DIRECTORY/ + + PATH = VALUES [TAGS] + +The first syntax defines a directory. It normally contains related +entries and the general scope of the directory is described. + +The second syntax defines a file entry containing values which are +either set by the hypervisor or, if the file is writable, can be set +by the user. + +PATH can contain simple regex constructs following the Perl compatible +regexp syntax described in pcre(3) or perlre(1). + +VALUES are strings and can take the following forms: + +* STRING -- an arbitrary string. +* INTEGER -- An integer, in decimal representation unless otherwise + noted. +* "a literal string" -- literal strings are contained within quotes. +* (VALUE | VALUE | ... ) -- a set of alternatives. Alternatives are + separated by a "|" and all the alternatives are enclosed in "(" and + ")". + +Additional TAGS may follow as a comma separated set of the following +tags enclosed in square brackets. + +* w -- Path is writable by the user. This capability is usually + limited to the control domain (e.g. dom0). +* ARM | ARM32 | X86: the path is available for the respective architecture + only. +* PV -- Path is valid for PV capable hypervisors only. +* HVM -- Path is valid for HVM capable hypervisors only. +* CONFIG_* -- Path is valid only in case the hypervisor was built with + the respective config option. + +## General Paths + +#### / + +The root of the hypervisor file system.