Re: [RFC PATCH v2 1/9] Add Rust SEV library as subproject

[Tyler Fanelli <tfanelli@redhat.com>]

On 10/5/23 11:54 AM, Stefan Hajnoczi wrote:
> On Wed, Oct 04, 2023 at 04:34:10PM -0400, Tyler Fanelli wrote:
>> The Rust sev library provides a C API for the AMD SEV launch ioctls, as
>> well as the ability to build with meson. Add the Rust sev library as a
>> QEMU subproject with the goal of outsourcing all SEV launch ioctls to C
>> APIs provided by it.
>>
>> Signed-off-by: Tyler Fanelli <tfanelli@redhat.com>
>> ---
>>   meson.build                   | 8 ++++++++
>>   meson_options.txt             | 2 ++
>>   scripts/meson-buildoptions.sh | 3 +++
>>   subprojects/sev.wrap          | 6 ++++++
>>   target/i386/meson.build       | 2 +-
>>   5 files changed, 20 insertions(+), 1 deletion(-)
>>   create mode 100644 subprojects/sev.wrap
>>
>> diff --git a/meson.build b/meson.build
>> index 20ceeb8158..8a17c29de8 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -960,6 +960,13 @@ if not get_option('slirp').auto() or have_system
>>     endif
>>   endif
>>   
>> +sev = not_found
>> +if not get_option('sev').auto()
> When 'sev' is auto, then it won't be built. That seems strange. The
> auto-detection part is missing! I did you test this on a system that
> doesn't have libsev installed system-wide?

My testing environment had libsev installed system-wide. Thanks for 
pointing this out.

>
> I guess the auto-detection would look something like:
>
>    cargo = find_program('cargo', required: true)
>
>    if not get_option('sev').auto() or cargo.found()
>        ...
>
> That way 'sev' is only built automatically on systems that have cargo
> installed.
>
>> +  sev = dependency('sev',
>> +                   method: 'pkg-config',
>> +                   required: get_option('sev'))
>> +endif
> If you update the auto logic, see the documentation about fallbacks to
> subprojects for optional dependencies:
> https://mesonbuild.com/Wrap-dependency-system-manual.html#provide-section
>
> It might be necessary to add dependency(..., fallback='sev').

Noted. Thanks!

>
>> +
>>   vde = not_found
>>   if not get_option('vde').auto() or have_system or have_tools
>>     vde = cc.find_library('vdeplug', has_headers: ['libvdeplug.h'],
>> @@ -4331,6 +4338,7 @@ summary_info += {'libudev':           libudev}
>>   # Dummy dependency, keep .found()
>>   summary_info += {'FUSE lseek':        fuse_lseek.found()}
>>   summary_info += {'selinux':           selinux}
>> +summary_info += {'sev':               sev}
>>   summary_info += {'libdw':             libdw}
>>   summary(summary_info, bool_yn: true, section: 'Dependencies')
>>   
>> diff --git a/meson_options.txt b/meson_options.txt
>> index 57e265c871..5b8d283717 100644
>> --- a/meson_options.txt
>> +++ b/meson_options.txt
>> @@ -204,6 +204,8 @@ option('sdl_image', type : 'feature', value : 'auto',
>>          description: 'SDL Image support for icons')
>>   option('seccomp', type : 'feature', value : 'auto',
>>          description: 'seccomp support')
>> +option('sev', type : 'feature', value : 'auto',
>> +        description: 'Rust AMD SEV library')
>>   option('smartcard', type : 'feature', value : 'auto',
>>          description: 'CA smartcard emulation support')
>>   option('snappy', type : 'feature', value : 'auto',
>> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
>> index e4b46d5715..e585a548fa 100644
>> --- a/scripts/meson-buildoptions.sh
>> +++ b/scripts/meson-buildoptions.sh
>> @@ -161,6 +161,7 @@ meson_options_help() {
>>     printf "%s\n" '  sdl-image       SDL Image support for icons'
>>     printf "%s\n" '  seccomp         seccomp support'
>>     printf "%s\n" '  selinux         SELinux support in qemu-nbd'
>> +  printf "%s\n" '  sev             SEV library support'
>>     printf "%s\n" '  slirp           libslirp user mode network backend support'
>>     printf "%s\n" '  slirp-smbd      use smbd (at path --smbd=*) in slirp networking'
>>     printf "%s\n" '  smartcard       CA smartcard emulation support'
>> @@ -440,6 +441,8 @@ _meson_option_parse() {
>>       --disable-seccomp) printf "%s" -Dseccomp=disabled ;;
>>       --enable-selinux) printf "%s" -Dselinux=enabled ;;
>>       --disable-selinux) printf "%s" -Dselinux=disabled ;;
>> +    --enable-sev) printf "%s" -Dsev=enabled ;;
>> +    --disable-sev) printf "%s" -Dsev=disabled ;;
>>       --enable-slirp) printf "%s" -Dslirp=enabled ;;
>>       --disable-slirp) printf "%s" -Dslirp=disabled ;;
>>       --enable-slirp-smbd) printf "%s" -Dslirp_smbd=enabled ;;
>> diff --git a/subprojects/sev.wrap b/subprojects/sev.wrap
>> new file mode 100644
>> index 0000000000..5be1faccf6
>> --- /dev/null
>> +++ b/subprojects/sev.wrap
>> @@ -0,0 +1,6 @@
>> +[wrap-git]
>> +url = https://github.com/tylerfanelli/sev
>> +revision = b81b1da5df50055600a5b0349b0c4afda677cccb
>> +
>> +[provide]
>> +sev = sev_dep
>> diff --git a/target/i386/meson.build b/target/i386/meson.build
>> index 6f1036d469..8972a4fb17 100644
>> --- a/target/i386/meson.build
>> +++ b/target/i386/meson.build
>> @@ -20,7 +20,7 @@ i386_system_ss.add(files(
>>     'monitor.c',
>>     'cpu-sysemu.c',
>>   ))
>> -i386_system_ss.add(when: 'CONFIG_SEV', if_true: files('sev.c'), if_false: files('sev-sysemu-stub.c'))
>> +i386_system_ss.add(when: 'CONFIG_SEV', if_true: [sev, files('sev.c')], if_false: files('sev-sysemu-stub.c'))
>>   
>>   i386_user_ss = ss.source_set()
>>   
>> -- 
>> 2.40.1
>>
Tyler