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xen/docs/misc/hypfs-paths.pandoc
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Juergen Gross 58263ed771 xen: add /buildinfo/config entry to hypervisor filesystem
Add the /buildinfo/config entry to the hypervisor filesystem. This
entry contains the .config file used to build the hypervisor.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
2020-05-29 12:15:54 +02:00

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# 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).
A hypervisor file system entry name can be any 0-delimited byte string
not containing any '/' character. The names "." and ".." are reserved
for file system internal use.
VALUES are strings and can take the following forms (note that this represents
only the syntax used in this document):
* STRING -- an arbitrary 0-delimited byte 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
")".
* {VALUE, VALUE, ... } -- a list of possible values separated by "," and
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 | ARM64 | 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.
So an entry could look like this:
/cpu-bugs/active-pv/xpti = ("No"|{"dom0", "domU", "PCID-on"}) [w,X86,PV]
Possible values would be "No" or a list of "dom0", "domU", and "PCID-on" with
the list elements separated by spaces, e.g. "dom0 PCID-on".
The entry would be writable and it would exist on X86 only and only if the
hypervisor is configured to support PV guests.
## Example
A populated Xen hypervisor file system might look like the following example:
/
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"
params/ directory with hypervisor parameter values
(boot/runtime parameters)
## General Paths
#### /
The root of the hypervisor file system.
#### /buildinfo/
A directory containing static information generated while building the
hypervisor.
#### /buildinfo/changeset = STRING
Git commit of the hypervisor.
#### /buildinfo/compileinfo/
A directory containing information about compilation of Xen.
#### /buildinfo/compileinfo/compile_by = STRING
Information who compiled the hypervisor.
#### /buildinfo/compileinfo/compile_date = STRING
Date of the hypervisor compilation.
#### /buildinfo/compileinfo/compile_domain = STRING
Information about the compile domain.
#### /buildinfo/compileinfo/compiler = STRING
The compiler used to build Xen.
#### /buildinfo/config = STRING [CONFIG_HYPFS_CONFIG]
The contents of the `xen/.config` file at the time of the hypervisor build.
#### /buildinfo/version/
A directory containing version information of the hypervisor.
#### /buildinfo/version/extra = STRING
Extra version information.
#### /buildinfo/version/major = INTEGER
The major version of Xen.
#### /buildinfo/version/minor = INTEGER
The minor version of Xen.