Re: [PATCH v2 1/1] target-i386: Fix default Hypervisor level for hypervisor-vendor=kvm.

[Don Slutz <Don@CloudSwitch.Com>]

On 09/21/12 16:49, Eduardo Habkost wrote:
> On Fri, Sep 21, 2012 at 04:26:58PM -0400, Don Slutz wrote:
>> On 09/21/12 10:18, Eduardo Habkost wrote:
>>> On Thu, Sep 20, 2012 at 04:06:27PM -0400, Don Slutz wrote:
>>>>  From http://lkml.indiana.edu/hypermail/linux/kernel/1205.0/00100.html
>>>> EAX should be KVM_CPUID_FEATURES (0x40000001) not 0.
>>>>
>>>> Added hypervisor-vendor=kvm0 to get the older CPUID result. kvm1 selects the newer one.
>>> Why not just make "hypervisor-vendor=kvm" control only the hypervisor
>>> vendor string, and support something like "kvm-hypervisor-level=0" to
>>> restore the old cpuid_hv_level=0 behavior?
>>    -cpu host,hypervisor-vendor=kvm,hypervisor-level=0
>>
>>   Does this.
> Good.  :-)
>
>>> This is similar to the kvmclock case: it would allow us to make
>>> "hypervisor-vendor=kvm" use saner values as default, but letting old
>>> machine-types to override it for compatibility if required.
>> Right now since I am using env->cpuid_hv_level == 0 as a flag. This
>> means that:
>>
>>    -cpu host,hypervisor-level=0,hypervisor-vendor=kvm
>>
>>    -cpu host,hypervisor-vendor=kvm,hypervisor-level=0
>>
>> end up with different CPUID data (Which I do not like). I will fix this in the next round.
> Right. This has to be fixed.
>
>> Did you want me to drop kvm0 and kvm1?
> Yes, if level is already configurable using the hypervisor-level
> property, I don't see the need for kvm0 and kvm1.
>
> If you make kvm_arch_init_vcpu() actually use those fields, you will end
> up implementing what's required to allow migration compatibility to be
> kept (the only thing missing is to make the CPU class a child of
> DeviceState, and add hypervisor-level=0 to the existing machine-types).
> :-)
>
You mean like
   http://lists.gnu.org/archive/html/qemu-devel/2012-09/msg03402.html
and
   http://lists.gnu.org/archive/html/qemu-devel/2012-09/msg03405.html
already change kvm_arch_init_vcpu().  I did not know that I need to make 
the CPU class a child of DeviceState.
Nor that I needed to add hypervisor-vendor=kvm,hypervisor-level=0 to the 
existing machine-types.  Since without specifying hypervisor-level=0 it 
defaults to 0 and kvm_arch_init_vcpu() will default to setting 
hypervisor-vendor=kvm.
    -Don