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xemu/docs/interop/firmware.json
Daniel P. Berrangé 2720ceda05 docs: expand firmware descriptor to allow flash without NVRAM 
The current firmware descriptor schema for flash requires that both the
executable to NVRAM template paths be provided. This is fine for the
most common usage of EDK2 builds in virtualization where the separate
_CODE and _VARS files are provided.

With confidential computing technology like AMD SEV, persistent storage
of variables may be completely disabled because the firmware requires a
known clean state on every cold boot. There is no way to express this
in the firmware descriptor today.

Even with regular EDK2 builds it is possible to create a firmware that
has both executable code and variable persistence in a single file. This
hasn't been commonly used, since it would mean every guest bootup would
need to clone the full firmware file, leading to redundant duplicate
storage of the code portion. In some scenarios this may not matter and
might even be beneficial. For example if a public cloud allows users to
bring their own firmware, such that the user can pre-enroll their own
secure boot keys, you're going to have this copied on disk for each
tenant already. At this point the it can be simpler to just deal with
a single file rather than split builds. The firmware descriptor ought
to be able to express this combined firmware model too.

This all points towards expanding the schema for flash with a 'mode'
concept:

 - "split" - the current implicit behaviour with separate files
   for code and variables.

 - "combined" - the alternate behaviour where a single file contains
   both code and variables.

 - "stateless" - the confidential computing use case where storage
   of variables is completely disable, leaving only the code.

Reviewed-by: Kashyap Chamarthy <kchamart@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2022-02-16 18:53:26 +00:00

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# -*- Mode: Python -*-
# vim: filetype=python
#
# Copyright (C) 2018 Red Hat, Inc.
#
# Authors:
# Daniel P. Berrange <berrange@redhat.com>
# Laszlo Ersek <lersek@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2 or
# later. See the COPYING file in the top-level directory.
##
# = Firmware
##
{ 'include' : 'machine.json' }
{ 'include' : 'block-core.json' }
##
# @FirmwareOSInterface:
#
# Lists the firmware-OS interface types provided by various firmware
# that is commonly used with QEMU virtual machines.
#
# @bios: Traditional x86 BIOS interface. For example, firmware built
# from the SeaBIOS project usually provides this interface.
#
# @openfirmware: The interface is defined by the (historical) IEEE
# 1275-1994 standard. Examples for firmware projects that
# provide this interface are: OpenBIOS and SLOF.
#
# @uboot: Firmware interface defined by the U-Boot project.
#
# @uefi: Firmware interface defined by the UEFI specification. For
# example, firmware built from the edk2 (EFI Development Kit II)
# project usually provides this interface.
#
# Since: 3.0
##
{ 'enum' : 'FirmwareOSInterface',
'data' : [ 'bios', 'openfirmware', 'uboot', 'uefi' ] }
##
# @FirmwareDevice:
#
# Defines the device types that firmware can be mapped into.
#
# @flash: The firmware executable and its accompanying NVRAM file are to
# be mapped into a pflash chip each.
#
# @kernel: The firmware is to be loaded like a Linux kernel. This is
# similar to @memory but may imply additional processing that
# is specific to the target architecture and machine type.
#
# @memory: The firmware is to be mapped into memory.
#
# Since: 3.0
##
{ 'enum' : 'FirmwareDevice',
'data' : [ 'flash', 'kernel', 'memory' ] }
##
# @FirmwareTarget:
#
# Defines the machine types that firmware may execute on.
#
# @architecture: Determines the emulation target (the QEMU system
# emulator) that can execute the firmware.
#
# @machines: Lists the machine types (known by the emulator that is
# specified through @architecture) that can execute the
# firmware. Elements of @machines are supposed to be concrete
# machine types, not aliases. Glob patterns are understood,
# which is especially useful for versioned machine types.
# (For example, the glob pattern "pc-i440fx-*" matches
# "pc-i440fx-2.12".) On the QEMU command line, "-machine
# type=..." specifies the requested machine type (but that
# option does not accept glob patterns).
#
# Since: 3.0
##
{ 'struct' : 'FirmwareTarget',
'data' : { 'architecture' : 'SysEmuTarget',
'machines' : [ 'str' ] } }
##
# @FirmwareFeature:
#
# Defines the features that firmware may support, and the platform
# requirements that firmware may present.
#
# @acpi-s3: The firmware supports S3 sleep (suspend to RAM), as defined
# in the ACPI specification. On the "pc-i440fx-*" machine
# types of the @i386 and @x86_64 emulation targets, S3 can be
# enabled with "-global PIIX4_PM.disable_s3=0" and disabled
# with "-global PIIX4_PM.disable_s3=1". On the "pc-q35-*"
# machine types of the @i386 and @x86_64 emulation targets, S3
# can be enabled with "-global ICH9-LPC.disable_s3=0" and
# disabled with "-global ICH9-LPC.disable_s3=1".
#
# @acpi-s4: The firmware supports S4 hibernation (suspend to disk), as
# defined in the ACPI specification. On the "pc-i440fx-*"
# machine types of the @i386 and @x86_64 emulation targets, S4
# can be enabled with "-global PIIX4_PM.disable_s4=0" and
# disabled with "-global PIIX4_PM.disable_s4=1". On the
# "pc-q35-*" machine types of the @i386 and @x86_64 emulation
# targets, S4 can be enabled with "-global
# ICH9-LPC.disable_s4=0" and disabled with "-global
# ICH9-LPC.disable_s4=1".
#
# @amd-sev: The firmware supports running under AMD Secure Encrypted
# Virtualization, as specified in the AMD64 Architecture
# Programmer's Manual. QEMU command line options related to
# this feature are documented in
# "docs/amd-memory-encryption.txt".
#
# @amd-sev-es: The firmware supports running under AMD Secure Encrypted
# Virtualization - Encrypted State, as specified in the AMD64
# Architecture Programmer's Manual. QEMU command line options
# related to this feature are documented in
# "docs/amd-memory-encryption.txt".
#
# @enrolled-keys: The variable store (NVRAM) template associated with
# the firmware binary has the UEFI Secure Boot
# operational mode turned on, with certificates
# enrolled.
#
# @requires-smm: The firmware requires the platform to emulate SMM
# (System Management Mode), as defined in the AMD64
# Architecture Programmer's Manual, and in the Intel(R)64
# and IA-32 Architectures Software Developer's Manual. On
# the "pc-q35-*" machine types of the @i386 and @x86_64
# emulation targets, SMM emulation can be enabled with
# "-machine smm=on". (On the "pc-q35-*" machine types of
# the @i386 emulation target, @requires-smm presents
# further CPU requirements; one combination known to work
# is "-cpu coreduo,nx=off".) If the firmware is marked as
# both @secure-boot and @requires-smm, then write
# accesses to the pflash chip (NVRAM) that holds the UEFI
# variable store must be restricted to code that executes
# in SMM, using the additional option "-global
# driver=cfi.pflash01,property=secure,value=on".
# Furthermore, a large guest-physical address space
# (comprising guest RAM, memory hotplug range, and 64-bit
# PCI MMIO aperture), and/or a high VCPU count, may
# present high SMRAM requirements from the firmware. On
# the "pc-q35-*" machine types of the @i386 and @x86_64
# emulation targets, the SMRAM size may be increased
# above the default 16MB with the "-global
# mch.extended-tseg-mbytes=uint16" option. As a rule of
# thumb, the default 16MB size suffices for 1TB of
# guest-phys address space and a few tens of VCPUs; for
# every further TB of guest-phys address space, add 8MB
# of SMRAM. 48MB should suffice for 4TB of guest-phys
# address space and 2-3 hundred VCPUs.
#
# @secure-boot: The firmware implements the software interfaces for UEFI
# Secure Boot, as defined in the UEFI specification. Note
# that without @requires-smm, guest code running with
# kernel privileges can undermine the security of Secure
# Boot.
#
# @verbose-dynamic: When firmware log capture is enabled, the firmware
# logs a large amount of debug messages, which may
# impact boot performance. With log capture disabled,
# there is no boot performance impact. On the
# "pc-i440fx-*" and "pc-q35-*" machine types of the
# @i386 and @x86_64 emulation targets, firmware log
# capture can be enabled with the QEMU command line
# options "-chardev file,id=fwdebug,path=LOGFILEPATH
# -device isa-debugcon,iobase=0x402,chardev=fwdebug".
# @verbose-dynamic is mutually exclusive with
# @verbose-static.
#
# @verbose-static: The firmware unconditionally produces a large amount
# of debug messages, which may impact boot performance.
# This feature may typically be carried by certain UEFI
# firmware for the "virt-*" machine types of the @arm
# and @aarch64 emulation targets, where the debug
# messages are written to the first (always present)
# PL011 UART. @verbose-static is mutually exclusive
# with @verbose-dynamic.
#
# Since: 3.0
##
{ 'enum' : 'FirmwareFeature',
'data' : [ 'acpi-s3', 'acpi-s4', 'amd-sev', 'amd-sev-es', 'enrolled-keys',
'requires-smm', 'secure-boot', 'verbose-dynamic',
'verbose-static' ] }
##
# @FirmwareFlashFile:
#
# Defines common properties that are necessary for loading a firmware
# file into a pflash chip. The corresponding QEMU command line option is
# "-drive file=@filename,format=@format". Note however that the
# option-argument shown here is incomplete; it is completed under
# @FirmwareMappingFlash.
#
# @filename: Specifies the filename on the host filesystem where the
# firmware file can be found.
#
# @format: Specifies the block format of the file pointed-to by
# @filename, such as @raw or @qcow2.
#
# Since: 3.0
##
{ 'struct' : 'FirmwareFlashFile',
'data' : { 'filename' : 'str',
'format' : 'BlockdevDriver' } }
##
# @FirmwareFlashType:
#
# Describes how the firmware build handles code versus variable
# persistence.
#
# @split: the executable file contains code while the NVRAM
# template provides variable storage. The executable
# must be configured read-only and can be shared between
# multiple guests. The NVRAM template must be cloned
# for each new guest and configured read-write.
#
# @combined: the executable file contains both code and
# variable storage. The executable must be cloned
# for each new guest and configured read-write.
# No NVRAM template will be specified.
#
# @stateless: the executable file contains code and variable
# storage is not persisted. The executable must
# be configured read-only and can be shared
# between multiple guests. No NVRAM template
# will be specified.
#
# Since: 7.0.0
##
{ 'enum': 'FirmwareFlashMode',
'data': [ 'split', 'combined', 'stateless' ] }
##
# @FirmwareMappingFlash:
#
# Describes loading and mapping properties for the firmware executable
# and its accompanying NVRAM file, when @FirmwareDevice is @flash.
#
# @mode: Describes how the firmware build handles code versus variable
# storage. If not present, it must be treated as if it was
# configured with value ``split``. Since: 7.0.0
#
# @executable: Identifies the firmware executable. The @mode
# indicates whether there will be an associated
# NVRAM template present. The preferred
# corresponding QEMU command line options are
# -drive if=none,id=pflash0,readonly=on,file=@executable.@filename,format=@executable.@format
# -machine pflash0=pflash0
# or equivalent -blockdev instead of -drive. When
# @mode is ``combined`` the executable must be
# cloned before use and configured with readonly=off.
# With QEMU versions older than 4.0, you have to use
# -drive if=pflash,unit=0,readonly=on,file=@executable.@filename,format=@executable.@format
#
# @nvram-template: Identifies the NVRAM template compatible with
# @executable, when @mode is set to ``split``,
# otherwise it should not be present.
# Management software instantiates an
# individual copy -- a specific NVRAM file -- from
# @nvram-template.@filename for each new virtual
# machine definition created. @nvram-template.@filename
# itself is never mapped into virtual machines, only
# individual copies of it are. An NVRAM file is
# typically used for persistently storing the
# non-volatile UEFI variables of a virtual machine
# definition. The preferred corresponding QEMU
# command line options are
# -drive if=none,id=pflash1,readonly=off,file=FILENAME_OF_PRIVATE_NVRAM_FILE,format=@nvram-template.@format
# -machine pflash1=pflash1
# or equivalent -blockdev instead of -drive.
# With QEMU versions older than 4.0, you have to use
# -drive if=pflash,unit=1,readonly=off,file=FILENAME_OF_PRIVATE_NVRAM_FILE,format=@nvram-template.@format
#
# Since: 3.0
##
{ 'struct' : 'FirmwareMappingFlash',
'data' : { '*mode': 'FirmwareFlashMode',
'executable' : 'FirmwareFlashFile',
'*nvram-template' : 'FirmwareFlashFile' } }
##
# @FirmwareMappingKernel:
#
# Describes loading and mapping properties for the firmware executable,
# when @FirmwareDevice is @kernel.
#
# @filename: Identifies the firmware executable. The firmware executable
# may be shared by multiple virtual machine definitions. The
# corresponding QEMU command line option is "-kernel
# @filename".
#
# Since: 3.0
##
{ 'struct' : 'FirmwareMappingKernel',
'data' : { 'filename' : 'str' } }
##
# @FirmwareMappingMemory:
#
# Describes loading and mapping properties for the firmware executable,
# when @FirmwareDevice is @memory.
#
# @filename: Identifies the firmware executable. The firmware executable
# may be shared by multiple virtual machine definitions. The
# corresponding QEMU command line option is "-bios
# @filename".
#
# Since: 3.0
##
{ 'struct' : 'FirmwareMappingMemory',
'data' : { 'filename' : 'str' } }
##
# @FirmwareMapping:
#
# Provides a discriminated structure for firmware to describe its
# loading / mapping properties.
#
# @device: Selects the device type that the firmware must be mapped
# into.
#
# Since: 3.0
##
{ 'union' : 'FirmwareMapping',
'base' : { 'device' : 'FirmwareDevice' },
'discriminator' : 'device',
'data' : { 'flash' : 'FirmwareMappingFlash',
'kernel' : 'FirmwareMappingKernel',
'memory' : 'FirmwareMappingMemory' } }
##
# @Firmware:
#
# Describes a firmware (or a firmware use case) to management software.
#
# It is possible for multiple @Firmware elements to match the search
# criteria of management software. Applications thus need rules to pick
# one of the many matches, and users need the ability to override distro
# defaults.
#
# It is recommended to create firmware JSON files (each containing a
# single @Firmware root element) with a double-digit prefix, for example
# "50-ovmf.json", "50-seabios-256k.json", etc, so they can be sorted in
# predictable order. The firmware JSON files should be searched for in
# three directories:
#
# - /usr/share/qemu/firmware -- populated by distro-provided firmware
# packages (XDG_DATA_DIRS covers
# /usr/share by default),
#
# - /etc/qemu/firmware -- exclusively for sysadmins' local additions,
#
# - $XDG_CONFIG_HOME/qemu/firmware -- exclusively for per-user local
# additions (XDG_CONFIG_HOME
# defaults to $HOME/.config).
#
# Top-down, the list of directories goes from general to specific.
#
# Management software should build a list of files from all three
# locations, then sort the list by filename (i.e., last pathname
# component). Management software should choose the first JSON file on
# the sorted list that matches the search criteria. If a more specific
# directory has a file with same name as a less specific directory, then
# the file in the more specific directory takes effect. If the more
# specific file is zero length, it hides the less specific one.
#
# For example, if a distro ships
#
# - /usr/share/qemu/firmware/50-ovmf.json
#
# - /usr/share/qemu/firmware/50-seabios-256k.json
#
# then the sysadmin can prevent the default OVMF being used at all with
#
# $ touch /etc/qemu/firmware/50-ovmf.json
#
# The sysadmin can replace/alter the distro default OVMF with
#
# $ vim /etc/qemu/firmware/50-ovmf.json
#
# or they can provide a parallel OVMF with higher priority
#
# $ vim /etc/qemu/firmware/10-ovmf.json
#
# or they can provide a parallel OVMF with lower priority
#
# $ vim /etc/qemu/firmware/99-ovmf.json
#
# @description: Provides a human-readable description of the firmware.
# Management software may or may not display @description.
#
# @interface-types: Lists the types of interfaces that the firmware can
# expose to the guest OS. This is a non-empty, ordered
# list; entries near the beginning of @interface-types
# are considered more native to the firmware, and/or
# to have a higher quality implementation in the
# firmware, than entries near the end of
# @interface-types.
#
# @mapping: Describes the loading / mapping properties of the firmware.
#
# @targets: Collects the target architectures (QEMU system emulators)
# and their machine types that may execute the firmware.
#
# @features: Lists the features that the firmware supports, and the
# platform requirements it presents.
#
# @tags: A list of auxiliary strings associated with the firmware for
# which @description is not appropriate, due to the latter's
# possible exposure to the end-user. @tags serves development and
# debugging purposes only, and management software shall
# explicitly ignore it.
#
# Since: 3.0
#
# Examples:
#
# {
# "description": "SeaBIOS",
# "interface-types": [
# "bios"
# ],
# "mapping": {
# "device": "memory",
# "filename": "/usr/share/seabios/bios-256k.bin"
# },
# "targets": [
# {
# "architecture": "i386",
# "machines": [
# "pc-i440fx-*",
# "pc-q35-*"
# ]
# },
# {
# "architecture": "x86_64",
# "machines": [
# "pc-i440fx-*",
# "pc-q35-*"
# ]
# }
# ],
# "features": [
# "acpi-s3",
# "acpi-s4"
# ],
# "tags": [
# "CONFIG_BOOTSPLASH=n",
# "CONFIG_ROM_SIZE=256",
# "CONFIG_USE_SMM=n"
# ]
# }
#
# {
# "description": "OVMF with SB+SMM, empty varstore",
# "interface-types": [
# "uefi"
# ],
# "mapping": {
# "device": "flash",
# "executable": {
# "filename": "/usr/share/OVMF/OVMF_CODE.secboot.fd",
# "format": "raw"
# },
# "nvram-template": {
# "filename": "/usr/share/OVMF/OVMF_VARS.fd",
# "format": "raw"
# }
# },
# "targets": [
# {
# "architecture": "x86_64",
# "machines": [
# "pc-q35-*"
# ]
# }
# ],
# "features": [
# "acpi-s3",
# "amd-sev",
# "requires-smm",
# "secure-boot",
# "verbose-dynamic"
# ],
# "tags": [
# "-a IA32",
# "-a X64",
# "-p OvmfPkg/OvmfPkgIa32X64.dsc",
# "-t GCC48",
# "-b DEBUG",
# "-D SMM_REQUIRE",
# "-D SECURE_BOOT_ENABLE",
# "-D FD_SIZE_4MB"
# ]
# }
#
# {
# "description": "OVMF with SB+SMM, SB enabled, MS certs enrolled",
# "interface-types": [
# "uefi"
# ],
# "mapping": {
# "device": "flash",
# "executable": {
# "filename": "/usr/share/OVMF/OVMF_CODE.secboot.fd",
# "format": "raw"
# },
# "nvram-template": {
# "filename": "/usr/share/OVMF/OVMF_VARS.secboot.fd",
# "format": "raw"
# }
# },
# "targets": [
# {
# "architecture": "x86_64",
# "machines": [
# "pc-q35-*"
# ]
# }
# ],
# "features": [
# "acpi-s3",
# "amd-sev",
# "enrolled-keys",
# "requires-smm",
# "secure-boot",
# "verbose-dynamic"
# ],
# "tags": [
# "-a IA32",
# "-a X64",
# "-p OvmfPkg/OvmfPkgIa32X64.dsc",
# "-t GCC48",
# "-b DEBUG",
# "-D SMM_REQUIRE",
# "-D SECURE_BOOT_ENABLE",
# "-D FD_SIZE_4MB"
# ]
# }
#
# {
# "description": "OVMF with SEV-ES support",
# "interface-types": [
# "uefi"
# ],
# "mapping": {
# "device": "flash",
# "executable": {
# "filename": "/usr/share/OVMF/OVMF_CODE.fd",
# "format": "raw"
# },
# "nvram-template": {
# "filename": "/usr/share/OVMF/OVMF_VARS.fd",
# "format": "raw"
# }
# },
# "targets": [
# {
# "architecture": "x86_64",
# "machines": [
# "pc-q35-*"
# ]
# }
# ],
# "features": [
# "acpi-s3",
# "amd-sev",
# "amd-sev-es",
# "verbose-dynamic"
# ],
# "tags": [
# "-a X64",
# "-p OvmfPkg/OvmfPkgX64.dsc",
# "-t GCC48",
# "-b DEBUG",
# "-D FD_SIZE_4MB"
# ]
# }
#
# {
# "description": "UEFI firmware for ARM64 virtual machines",
# "interface-types": [
# "uefi"
# ],
# "mapping": {
# "device": "flash",
# "executable": {
# "filename": "/usr/share/AAVMF/AAVMF_CODE.fd",
# "format": "raw"
# },
# "nvram-template": {
# "filename": "/usr/share/AAVMF/AAVMF_VARS.fd",
# "format": "raw"
# }
# },
# "targets": [
# {
# "architecture": "aarch64",
# "machines": [
# "virt-*"
# ]
# }
# ],
# "features": [
#
# ],
# "tags": [
# "-a AARCH64",
# "-p ArmVirtPkg/ArmVirtQemu.dsc",
# "-t GCC48",
# "-b DEBUG",
# "-D DEBUG_PRINT_ERROR_LEVEL=0x80000000"
# ]
# }
##
{ 'struct' : 'Firmware',
'data' : { 'description' : 'str',
'interface-types' : [ 'FirmwareOSInterface' ],
'mapping' : 'FirmwareMapping',
'targets' : [ 'FirmwareTarget' ],
'features' : [ 'FirmwareFeature' ],
'tags' : [ 'str' ] } }
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