[libvirt PATCH 1/2] qemu: remove use of (+|-)name syntax for -cpu featres

[Peter Krempa]

On Tue, Oct 05, 2021 at 18:07:03 +0100, Daniel P. Berrangé wrote:
> The -cpu arg gained support for feature=on|off syntax for the x86
> emulator in 2.4.0
> 
>   commit 38e5c119c2925812bd441450ab9e5e00fc79e662
>   Author: Eduardo Habkost <ehabkost at redhat.com>
>   Date:   Mon Mar 23 17:29:32 2015 -0300
> 
>     target-i386: Register QOM properties for feature flags
> 
> Most other targets gained this syntax even earlier in 1.4.1
> 
>   commit 1590bbcb02921dfe8e3cf66e3a3aafd31193babf
>   Author: Andreas Färber <afaerber at suse.de>
>   Date:   Mon Mar 3 23:33:51 2014 +0100
> 
>     cpu: Implement CPUClass::parse_features() for the rest of CPUs
> 
>     CPUs who do not provide their own implementation of feature parsing
>     will treat each option as a QOM property and set it to the supplied
>     value.
> 
> There appears no reason to keep supporting "+|-feature" syntax,
> given the current minimum QEMU version.
> 
> Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
> ---

[...]

> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> index eaa1e0deb9..a1dba1cb7e 100644
> --- a/src/qemu/qemu_command.c
> +++ b/src/qemu/qemu_command.c
> @@ -6242,21 +6242,6 @@ qemuBuildGlobalControllerCommandLine(virCommand *cmd,
>  }
>  
>  
> -static void
> -qemuBuildCpuFeature(virQEMUCaps *qemuCaps,
> -                    virBuffer *buf,
> -                    const char *name,
> -                    bool state)
> -{
> -    name = virQEMUCapsCPUFeatureToQEMU(qemuCaps, name);

This function, which is no longer called ...


> -
> -    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION))
> -        virBufferAsprintf(buf, ",%s=%s", name, state ? "on" : "off");
> -    else
> -        virBufferAsprintf(buf, ",%c%s", state ? '+' : '-', name);
> -}
> -
> -
>  static int
>  qemuBuildCpuModelArgStr(virQEMUDriver *driver,
>                          const virDomainDef *def,
> @@ -6332,12 +6317,12 @@ qemuBuildCpuModelArgStr(virQEMUDriver *driver,
>          switch ((virCPUFeaturePolicy) cpu->features[i].policy) {
>          case VIR_CPU_FEATURE_FORCE:
>          case VIR_CPU_FEATURE_REQUIRE:
> -            qemuBuildCpuFeature(qemuCaps, buf, cpu->features[i].name, true);
> +            virBufferAsprintf(buf, ",%s=on", cpu->features[i].name);
>              break;
>  
>          case VIR_CPU_FEATURE_DISABLE:
>          case VIR_CPU_FEATURE_FORBID:
> -            qemuBuildCpuFeature(qemuCaps, buf, cpu->features[i].name, false);
> +            virBufferAsprintf(buf, ",%s=off", cpu->features[i].name);

... here ...

>              break;
>  
>          case VIR_CPU_FEATURE_OPTIONAL:

[...]

> diff --git a/tests/qemuxml2argvdata/cpu-host-model.x86_64-5.0.0.args b/tests/qemuxml2argvdata/cpu-host-model.x86_64-5.0.0.args
> index 3ce594ba13..7f29bcd10d 100644

... is causing a change even on modern versions ...

> --- a/tests/qemuxml2argvdata/cpu-host-model.x86_64-5.0.0.args
> +++ b/tests/qemuxml2argvdata/cpu-host-model.x86_64-5.0.0.args
> @@ -11,7 +11,7 @@ XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \
>  -S \
>  -object secret,id=masterKey0,format=raw,file=/tmp/lib/domain--1-QEMUGuest1/master-key.aes \
>  -machine pc-q35-5.0,accel=kvm,usb=off,dump-guest-core=off \
> --cpu Skylake-Client-IBRS,ss=on,vmx=on,hypervisor=on,tsc-adjust=on,clflushopt=on,umip=on,md-clear=on,stibp=on,arch-capabilities=on,ssbd=on,xsaves=on,pdpe1gb=on,skip-l1dfl-vmentry=on,pschange-mc-no=on \
> +-cpu Skylake-Client-IBRS,ss=on,vmx=on,hypervisor=on,tsc_adjust=on,clflushopt=on,umip=on,md-clear=on,stibp=on,arch-capabilities=on,ssbd=on,xsaves=on,pdpe1gb=on,skip-l1dfl-vmentry=on,pschange-mc-no=on \

... which should not have been impacted. Specifically the changed thing
it the above commandline is
(it's rather hard to spot):

tsc-adjust -> tsc_adjust