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df13c0b477
This patch maps /domain/cpu/cache element into -cpu parameters: - <cache mode='passthrough'/> is translated to host-cache-info=on - <cache level='3' mode='emulate'/> is transformed into l3-cache=on - <cache mode='disable'/> is turned in host-cache-info=off,l3-cache=off Any other <cache> element is forbidden. The tricky part is detecting whether QEMU supports the CPU properties. The 'host-cache-info' property is introduced in v2.4.0-1389-ge265e3e480, earlier QEMU releases enabled host-cache-info by default and had no way to disable it. If the property is present, it defaults to 'off' for any QEMU until at least 2.9.0. The 'l3-cache' property was introduced later by v2.7.0-200-g14c985cffa. Earlier versions worked as if l3-cache=off was passed. For any QEMU until at least 2.9.0 l3-cache is 'off' by default. QEMU 2.9.0 was the first release which supports probing both properties by running device-list-properties with typename=host-x86_64-cpu. Older QEMU releases did not support device-list-properties command for CPU devices. Thus we can't really rely on probing them and we can just use query-cpu-model-expansion QMP command as a witness. Because the cache property probing is only reliable for QEMU >= 2.9.0 when both are already supported for quite a few releases, we let QEMU report an error if a specific cache mode is explicitly requested. The other mode (or both if a user requested CPU cache to be disabled) is explicitly turned off for QEMU >= 2.9.0 to avoid any surprises in case the QEMU defaults change. Any older QEMU already turns them off so not doing so explicitly does not make any harm. Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
21 lines
526 B
XML
21 lines
526 B
XML
<domain type='kvm'>
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<name>foo</name>
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<uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
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<memory unit='KiB'>219136</memory>
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<currentMemory unit='KiB'>219136</currentMemory>
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<vcpu placement='static'>1</vcpu>
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<os>
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<type arch='x86_64' machine='pc'>hvm</type>
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<boot dev='hd'/>
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</os>
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<cpu mode='host-model'>
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<cache mode='passthrough'/>
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</cpu>
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<clock offset='utc'/>
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<on_poweroff>destroy</on_poweroff>
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<on_reboot>restart</on_reboot>
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<on_crash>destroy</on_crash>
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<devices>
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</devices>
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</domain>
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