Re: [PATCH v2 00/22] qga: clean up command source locations and conditionals

[Daniel P . Berrangé]

Ping: for any review comments from QGA maintainers ?

On Thu, Jun 13, 2024 at 04:01:05PM +0100, Daniel P. Berrangé wrote:
> This series is a side effect of other work I started, to attempt to
> make the QGA safe to use in confidential VMs by automatically
> restricting the permitted commands. Since this cleanup stands on
> its own, I'm sending it now.
> 
> The QGA codebase has a very complicated maze of #ifdefs to create
> stubs for the various commands that cannot be implemented on certain
> platforms. It then has further logic to dynamically disable the stub
> commands at runtime, except this is not consistently applied, so
> some commands remain enabled despite being merely stubs.
> 
> The resulting code is hard to follow, when trying to understand exactly
> what commands are available under what circumstances, and when changing
> impls it is easy to get the #ifdefs wrong, resulting in stubs getting
> missed on platforms without a real impl. In some cases, we have multiple
> stubs for the same command, due to the maze of #ifdefs.
> 
> The QAPI schema language has support for many years for expressing
> conditions against commands when declaring them. This results in the
> QAPI code generator omitting their implementation entirely at build
> time. This has mutliple benefits
> 
>  * The unsupported commands are guaranteed to not exist at runtime
>  * No stubs need ever be defined in the code
>  * The generated QAPI reference manual documents the build conditions
> 
> This series is broadly split into three parts
> 
>  * Moving tonnes of Linux only commands out of commands-posix.c
>    into commands-linux.c to remove many #ifdefs.
>  * Adding 'if' conditions in the QAPI schema to reflect the
>    build conditions, removing many more #ifdefs
>  * Sanitizing the logic for disabling/enabling commands at
>    runtime to guarantee consistency
> 
> Changed in v2:
> 
>  - Make FSFreeze error reporting distinguish inability to enable
>    VSS from user config choice
> 
>  - Fully remove ga_command_init_blockedrpcs() methods. No more
>    special case disabling of commands. Either they're disabled
>    at build time, or disabled by user config, or by well defined
>    rule ie not permitted during FS freeze.
> 
>  - Apply rules later in startup to avoid crash from NULL config
>    pointer
> 
>  - Document changed error messages in commit messages
> 
>  - Add -c / --config command line parameter
> 
>  - Fix mistaken enabling of fsfreeze hooks on win32
> 
>  - Remove pointless 'blockrpcs_key' variable
> 
>  - Allow concurrent setting of allow and block lists for
>    RPC commands
> 
> Daniel P. Berrangé (22):
>   qga: drop blocking of guest-get-memory-block-size command
>   qga: move linux vcpu command impls to commands-linux.c
>   qga: move linux suspend command impls to commands-linux.c
>   qga: move linux fs/disk command impls to commands-linux.c
>   qga: move linux disk/cpu stats command impls to commands-linux.c
>   qga: move linux memory block command impls to commands-linux.c
>   qga: move CONFIG_FSFREEZE/TRIM to be meson defined options
>   qga: conditionalize schema for commands unsupported on Windows
>   qga: conditionalize schema for commands unsupported on non-Linux POSIX
>   qga: conditionalize schema for commands requiring getifaddrs
>   qga: conditionalize schema for commands requiring linux/win32
>   qga: conditionalize schema for commands only supported on Windows
>   qga: conditionalize schema for commands requiring fsfreeze
>   qga: conditionalize schema for commands requiring fstrim
>   qga: conditionalize schema for commands requiring libudev
>   qga: conditionalize schema for commands requiring utmpx
>   qga: conditionalize schema for commands not supported on other UNIX
>   qga: don't disable fsfreeze commands if vss_init fails
>   qga: move declare of QGAConfig struct to top of file
>   qga: remove pointless 'blockrpcs_key' variable
>   qga: allow configuration file path via the cli
>   qga: centralize logic for disabling/enabling commands
> 
>  docs/interop/qemu-ga.rst |   19 +
>  meson.build              |   16 +
>  qga/commands-bsd.c       |   24 -
>  qga/commands-common.h    |    9 -
>  qga/commands-linux.c     | 1805 +++++++++++++++++++++++++++++
>  qga/commands-posix.c     | 2373 +++-----------------------------------
>  qga/commands-win32.c     |   78 +-
>  qga/main.c               |  216 ++--
>  qga/qapi-schema.json     |  153 ++-
>  9 files changed, 2234 insertions(+), 2459 deletions(-)
> 
> -- 
> 2.45.1
> 

With regards,
Daniel
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