[libvirt] [PATCH 1/1][RESEND] ppc64 cpu features

[Li Zhang]

On 2013年04月19日 22:04, Jiri Denemark wrote:
> On Thu, Mar 14, 2013 at 14:54:21 +0800, Li Zhang wrote:
>> From: Li Zhang <zhlcindy at linux.vnet.ibm.com>
>>
>> This patch adds a CPU feature "powernv" identifying IBM Power
>> processor that supports native hypervisor e.g. KVM. This can
>> be used by virtualization management software to determine
>> the CPU capabilities. PVR doesn't indicate whether it a
>> host or a guest CPU. So, we use /proc/cpuinfo to get the
>> platform information (PowerNV) and use that to set the
>> "powernv" flag.
>>
>> Signed-off-by: Dipankar Sarma <dipankar at in.ibm.com>
>> Signed-off-by: Li Zhang <zhlcindy at linux.vnet.ibm.com>
>> ---
>>   src/cpu/cpu_map.xml    |    9 ++
>>   src/cpu/cpu_powerpc.c  |  349 ++++++++++++++++++++++++++++++++++++++----------
>>   src/cpu/cpu_ppc_data.h |    4 +
>>   src/util/sysinfo.c     |    2 +-
>>   4 files changed, 294 insertions(+), 70 deletions(-)
> Looks like this patch was not even rebased since it was written back in
> time 1.0.1 was released. Anyway, I realized I did not push my changes to
> powerpc driver so I did that. And I also started rewriting this patch on
> top of it since this patch is rather huge and seems to mix lots of
> things. Also PowerPC CPUs seem to be quite different from x86 CPUs so
> enhancing powerpc driver by copy&pasting code from x86 driver is not the
> best way :-) It just makes powerpc driver unnecessarily complicated.

We hope it matches x86 driver, so most code are from x86.
There is no CPUID on powerpc, but we also need feature such as "powernv".

>>     <arch name='ppc64'>
>>      <!-- vendor definitions -->
>>       <vendor name='IBM' string='PowerPC'/>
>> +    <feature name='powernv'> <!-- SYSTEMID_POWERNV -->
>> +      <systemid platform='0x00000001'/>
>> +    </feature>
>>      <!-- IBM-based CPU models -->
>>       <model name='POWER7'>
>> +      <feature name='powernv'/>
>> +      <systemid pvr='0x003f0200'/>
>>         <vendor name='IBM'/>
>>       </model>
>>       <model name='POWER7_v2.1'>
>> +      <feature name='powernv'/>
>> +      <systemid pvr='0x003f0201'/>
>>         <vendor name='IBM'/>
>>       </model>
>>       <model name='POWER7_v2.3'>
>> +      <feature name='powernv'/>
>> +      <systemid pvr='0x003f0203'/>
>>         <vendor name='IBM'/>
>>       </model>
>>     </arch>
> So what is this "powernv" feature used for? It won't show up in
> capabilities XML as it is included in all powerpc CPU models. That also

This feature means that powerpc can support KVM.
Other platform, for example, pseries doesn't support KVM.
So we need this feature.

Currently, we haven't introduced this feature in capabilities XML yet.

> means, users don't need to explicitly enable it when configuring guest
> CPU. Thus it could only make sense to allow users to disable this
> feature for a given guest. However, I don't see "powernv" string
> anywhere in QEMU source code and thus it cannot really be used in any
> way in guest CPU definition.

This feature is from sysinfo on host, not from QEMU.
QEMU haven't included this feature yet.
I am not sure whether it is necessary to introduce this to QEMU.

> Jirka