qemu: Add script to generate hypervisor configure options.

scripts/configure-hypervisor.sh

@@ -0,0 +1,393 @@
+#!/bin/bash
+#
+# Copyright (c) 2018 Intel Corporation
+#
+# SPDX-License-Identifier: Apache-2.0
+
+#---------------------------------------------------------------------
+# Description: This script is the *ONLY* place where "qemu*" build options
+# should be defined.
+#
+# Note to maintainers:
+#
+# XXX: Every option group *MUST* be documented explaining why it has
+# been specified.
+#---------------------------------------------------------------------
+
+script_name=${0##*/}
+
+typeset -A recognised_tags
+
+recognised_tags=(
+	[arch]="architecture-specific"
+	[functionality]="required functionality"
+	[minimal]="specified to avoid building unnecessary elements"
+	[misc]="miscellaneous"
+	[security]="specified for security reasons"
+	[size]="minimise binary size"
+	[speed]="maximise startup speed"
+)
+
+# Display message to stderr and exit indicating script failed.
+die()
+{
+	local msg="$*"
+	echo >&2 "$script_name: ERROR: $msg"
+	exit 1
+}
+
+# Display usage to stdout.
+usage()
+{
+cat <<EOT
+Overview:
+
+	Display configure options required to build the specified
+	hypervisor.
+
+Usage:
+
+	$script_name [options] <hypervisor-name>
+
+Options:
+
+	-d : Dump all options along with the tags explaining why each option
+	     is specified.
+	-h : Display this help.
+	-m : Display options one per line (includes continuation characters).
+
+Example:
+
+	$ $script_name qemu-lite
+
+EOT
+}
+
+show_tags_header()
+{
+	local keys
+	local key
+	local value
+
+	cat <<EOT
+# Recognised option tags:
+#
+EOT
+
+	# sort the tags
+	keys=${!recognised_tags[@]}
+	keys=$(echo "$keys"|tr ' ' '\n'|sort -u)
+
+	for key in $keys
+	do
+		value="${recognised_tags[$key]}"
+		printf "#    %s\t%s.\n" "$key" "$value"
+	done
+
+	printf "#\n\n"
+}
+
+check_tag()
+{
+	local tag="$1"
+	local entry="$2"
+
+	value="${recognised_tags[$tag]}"
+
+	[ -n "$value" ] && return
+
+	die "invalid tag '$tag' found for entry '$entry'"
+}
+
+check_tags()
+{
+	local tags="$1"
+	local entry="$2"
+
+	[ -z "$tags" ] && die "entry '$entry' doesn't have any tags"
+
+	tags=$(echo "$tags"|tr ',' '\n')
+
+	for tag in $tags
+	do
+		check_tag "$tag" "$entry"
+	done
+}
+
+# Display an array to stdout.
+#
+# If 2 arguments are specified, split array across multiple lines,
+# one per element with a backslash at the end of all lines except
+# the last.
+#
+# Arguments:
+#
+# $1: *Name* of array variable (no leading '$'!!)
+# $2: (optional) "multi" - show values across multiple lines,
+#    "dump" - show full hash values. Any other value results in the
+#    options being displayed on a single line.
+show_array()
+{
+	local -n _array="$1"
+	local action="$2"
+
+	local -i size="${#_array[*]}"
+	local -i i=1
+	local entry
+	local tags
+	local elem
+	local suffix
+	local one_line="no"
+
+	[ "$action" = "dump" ] && show_tags_header
+
+	for entry in "${_array[@]}"
+	do
+		tags=$(echo "$entry"|cut -s -d: -f1)
+		elem=$(echo "$entry"|cut -s -d: -f2-)
+
+		check_tags "$tags" "$entry"
+
+		if [ "$action" = "dump" ]
+		then
+			printf "%s\t\t%s\n" "$tags" "$elem"
+		elif [ "$action" = "multi" ]
+		then
+			if [ $i -eq $size ]
+			then
+				suffix=""
+			else
+				suffix=" \\"
+			fi
+
+			printf '%s%s\n' "$elem" "$suffix"
+		else
+			one_line="yes"
+			echo -n "$elem "
+		fi
+
+		i+=1
+	done
+
+	[ "$one_line" = yes ] && echo
+}
+
+# Entry point
+main()
+{
+	arch=$(arch)
+
+	# Array of configure options.
+	#
+	# Each element is comprised of two parts in the form:
+	#
+	#   tags:option
+	#
+	# Where,
+	#
+	# - 'tags' is a comma-separated list of values which denote why
+	#   the option is being specified.
+	#
+	# - 'option' is the hypervisor configuration option.
+	typeset -a qemu_options
+
+	action=""
+
+	while getopts "dhm" opt
+	do
+		case "$opt" in
+			d)
+				action="dump"
+				;;
+
+			h)
+				usage
+				exit 0
+				;;
+
+			m)
+				action="multi"
+				;;
+		esac
+	done
+
+	shift $[$OPTIND-1]
+
+	[ -z "$1" ] && die "need hypervisor name"
+	hypervisor="$1"
+
+	#---------------------------------------------------------------------
+	# Disabled options
+
+	# bluetooth support not required
+	qemu_options+=(size:--disable-bluez)
+
+	# braille support not required
+	qemu_options+=(size:--disable-brlapi)
+
+	# Don't build documentation
+	qemu_options+=(minimal:--disable-docs)
+
+	# Disable GUI (graphics)
+	qemu_options+=(size:--disable-curses)
+	qemu_options+=(size:--disable-gtk)
+	qemu_options+=(size:--disable-opengl)
+	qemu_options+=(size:--disable-sdl)
+	qemu_options+=(size:--disable-spice)
+	qemu_options+=(size:--disable-vte)
+
+	# Disable graphical network access
+	qemu_options+=(size:--disable-vnc)
+	qemu_options+=(size:--disable-vnc-jpeg)
+	qemu_options+=(size:--disable-vnc-png)
+	qemu_options+=(size:--disable-vnc-sasl)
+
+	# Disable unused filesystem support
+	qemu_options+=(size:--disable-fdt)
+	qemu_options+=(size:--disable-glusterfs)
+	qemu_options+=(size:--disable-libiscsi)
+	qemu_options+=(size:--disable-libnfs)
+	qemu_options+=(size:--disable-libssh2)
+
+	# Disable unused compression support
+	qemu_options+=(size:--disable-bzip2)
+	qemu_options+=(size:--disable-lzo)
+	qemu_options+=(size:--disable-snappy)
+
+	# Disable unused security options
+	qemu_options+=(security:--disable-seccomp)
+	qemu_options+=(security:--disable-tpm)
+
+	# Disable userspace network access ("-net user")
+	qemu_options+=(size:--disable-slirp)
+
+	# Disable USB
+	qemu_options+=(size:--disable-libusb)
+	qemu_options+=(size:--disable-usb-redir)
+
+	# Disable TCG support
+	qemu_options+=(size:--disable-tcg)
+
+	# Don't build a static binary (lowers security)
+	qemu_options+=(security:--disable-static)
+
+	# Not required as "-uuid ..." is always passed to the qemu binary
+	qemu_options+=(size:--disable-uuid)
+
+	# Disable debug
+	qemu_options+=(size:--disable-debug-tcg)
+	qemu_options+=(size:--disable-qom-cast-debug)
+	qemu_options+=(size:--disable-tcg-interpreter)
+	qemu_options+=(size:--disable-tcmalloc)
+
+	# Disallow network downloads
+	qemu_options+=(security:--disable-curl)
+
+	# Disable Remote Direct Memory Access (Live Migration)
+	# https://wiki.qemu.org/index.php/Features/RDMALiveMigration
+	qemu_options+=(size:--disable-rdma)
+
+	# Don't build the qemu-io, qemu-nbd and qemu-image tools
+	qemu_options+=(size:--disable-tools)
+
+	# Disable XEN driver
+	qemu_options+=(size:--disable-xen)
+
+	# FIXME: why is this disabled?
+	# (for reference, it's explicitly enabled in Ubuntu 17.10 and
+	# implicitly enabled in Fedora 27).
+	qemu_options+=(size:--disable-linux-aio)
+
+	#---------------------------------------------------------------------
+	# Enabled options
+
+	# Enable kernel Virtual Machine support.
+	# This is the default, but be explicit to avoid any future surprises
+	qemu_options+=(speed:--enable-kvm)
+
+	# Required for fast network access
+	qemu_options+=(speed:--enable-vhost-net)
+
+	# Always strip binaries
+	qemu_options+=(size:--enable-strip)
+
+	# Support Ceph RADOS Block Device (RBD)
+	qemu_options+=(functionality:--enable-rbd)
+
+	# In "passthrough" security mode
+	# (-fsdev "...,security_model=passthrough,..."), qemu uses a helper
+	# application called virtfs-proxy-helper(1) to make certain 9p
+	# operations safer.
+	qemu_options+=(functionality:--enable-virtfs)
+	qemu_options+=(functionality:--enable-attr)
+	qemu_options+=(functionality:--enable-cap-ng)
+
+	#---------------------------------------------------------------------
+	# Other options
+
+	# 64-bit only
+	[ "$arch" = x86_64 ] && qemu_options+=(arch:"--target-list=${arch}-softmmu")
+
+	_qemu_cflags=""
+
+	# compile with high level of optimisation
+	_qemu_cflags+=" -O3"
+
+	# Improve code quality by assuming identical semantics for interposed
+	# synmbols.
+	_qemu_cflags+=" -fno-semantic-interposition"
+
+	# Performance optimisation
+	_qemu_cflags+=" -falign-functions=32"
+
+	# SECURITY: make the compiler check for common security issues
+	# (such as argument and buffer overflows checks).
+	_qemu_cflags+=" -D_FORTIFY_SOURCE=2"
+
+	# SECURITY: Create binary as a Position Independant Executable,
+	# and take advantage of ASLR, making ROP attacks much harder to perform.
+	# (https://wiki.debian.org/Hardening)
+	_qemu_cflags+=" -fPIE"
+
+	# Set compile options
+	qemu_options+=(functionality,security,speed,size:"--extra-cflags=\"${_qemu_cflags}\"")
+
+	unset _qemu_cflags
+
+	_qemu_ldflags=""
+
+	# SECURITY: Link binary as a Position Independant Executable,
+	# and take advantage of ASLR, making ROP attacks much harder to perform.
+	# (https://wiki.debian.org/Hardening)
+	_qemu_ldflags+=" -pie"
+
+	# SECURITY: Disallow executing code on the stack.
+	_qemu_ldflags+=" -z noexecstack"
+
+	# SECURITY: Make the linker set some program sections to read-only
+	# before the program is run to stop certain attacks.
+	_qemu_ldflags+=" -z relro"
+
+	# SECURITY: Make the linker resolve all symbols immediately on program
+	# load.
+	_qemu_ldflags+=" -z now"
+
+	qemu_options+=(security:"--extra-ldflags=\"${_qemu_ldflags}\"")
+
+	unset _qemu_ldflags
+
+	# Where to install qemu libraries
+	[ "$arch" = x86_64 ] && qemu_options+=(arch:--libdir=/usr/lib64/${hypervisor})
+
+	# Where to install qemu helper binaries
+	qemu_options+=(misc:--libexecdir=/usr/libexec/${hypervisor})
+
+	# Where to install data files
+	qemu_options+=(misc:--datadir=/usr/share/${hypervisor})
+
+	show_array qemu_options "$action"
+
+	exit 0
+}
+
+main $@