[libvirt PATCH v2 1/2] qemu: remove use of (+|-)name syntax for -cpu featres
Daniel P. Berrangé
berrange at redhat.com
Thu Oct 7 12:24:37 UTC 2021
On Thu, Oct 07, 2021 at 12:36:14PM +0200, Jiri Denemark wrote:
> On Thu, Oct 07, 2021 at 11:09:19 +0100, Daniel P. Berrangé wrote:
> > On Thu, Oct 07, 2021 at 11:53:00AM +0200, Jiri Denemark wrote:
> > > On Thu, Oct 07, 2021 at 10:05:12 +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>
> > > > ---
> > > > src/qemu/qemu_command.c | 34 ++++++-------------
> > > > tests/qemuxml2argvdata/cpu-Haswell2.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-Haswell3.args | 2 +-
> > > > .../qemuxml2argvdata/cpu-cache-disable3.args | 2 +-
> > > > .../cpu-check-default-partial.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-eoi-disabled.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-eoi-enabled.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-exact1.args | 2 +-
> > > > .../cpu-exact2-nofallback.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-exact2.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-fallback.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-host-kvmclock.args | 2 +-
> > > > .../qemuxml2argvdata/cpu-host-model-cmt.args | 2 +-
> > > > .../cpu-host-model-fallback.args | 2 +-
> > > > .../cpu-host-model-vendor.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-host-model.args | 2 +-
> > > > .../cpu-host-passthrough-features.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-kvmclock.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-minimum1.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-minimum2.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-strict1.args | 2 +-
> > > > .../cpu-translation.x86_64-latest.args | 2 +-
> > > > tests/qemuxml2argvdata/cpu-tsc-frequency.args | 2 +-
> > > > .../eoi-disabled.x86_64-latest.args | 2 +-
> > > > .../eoi-enabled.x86_64-latest.args | 2 +-
> > > > .../graphics-spice-timeout.args | 2 +-
> > > > .../kvmclock+eoi-disabled.x86_64-latest.args | 2 +-
> > > > tests/qemuxml2argvdata/kvmclock.args | 2 +-
> > > > .../pci-bridge-many-disks.args | 2 +-
> > > > .../pv-spinlock-disabled.x86_64-latest.args | 2 +-
> > > > .../pv-spinlock-enabled.x86_64-latest.args | 2 +-
> > > > 31 files changed, 41 insertions(+), 53 deletions(-)
> > > >
> > > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
> > > > index eaa1e0deb9..0f1cdd9372 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);
> > > > -
> > > > - if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION))
> > > > - virBufferAsprintf(buf, ",%s=%s", name, state ? "on" : "off");
> > > > - else
> > > > - virBufferAsprintf(buf, ",%c%s", state ? '+' : '-', name);
> > > > -}
> > >
> > > I guess it would have been easier and perhaps clearer to just remove the
> > > else branch and the test itself, because...
> > >
> > > > @@ -6433,13 +6420,14 @@ qemuBuildCpuCommandLine(virCommand *cmd,
> > > > }
> > > >
> > > > if (def->apic_eoi) {
> > > > - qemuBuildCpuFeature(qemuCaps, &buf, "kvm_pv_eoi",
> > > > - def->apic_eoi == VIR_TRISTATE_SWITCH_ON);
> > > > + virBufferAsprintf(&buf, ",kvm_pv_eoi=%s", def->apic_eoi ==
> > > > + VIR_TRISTATE_SWITCH_ON ? "on" : "off");
> > >
> > > This is affected by the same issue spotted by Peter in v1. In other
> > > words, when replacing qemuBuildCpuFeature you need to make sure the
> > > feature name goes through virQEMUCapsCPUFeatureToQEMU().
> >
> > virQEMUCapsCPUFeatureToQEMU() is a constant mapping. It makes sense
> > to use it in the earlier loop, because we're getting feature names
> > dynamically from the XML config.
> >
> > In this case though, we've just got a constant string. Seems better
> > to just pass the right constant string in directly rather than send
> > it through this remapping.
>
> Well, only when QEMU_CAPS_CANONICAL_CPU_FEATURES is set. If it is always
> set for any QEMU we deal with, we can just drop it too, though.
IIUC, this CAPS is set based on whether QEMU_CAPS_CPU_UNAVAILABLE_FEATURES
is set. QAPI docs for @unavailable-features says
@unavailable-features: List of properties that prevent
the CPU model from running in the current
host. (since 2.8)
so feels like we can drop these caps, since we require QEMU >= 2.11
Regards,
Daniel
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