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

[Don Slutz <Don@CloudSwitch.com>]

On 09/21/12 17:53, Eduardo Habkost wrote:
> On Fri, Sep 21, 2012 at 05:28:27PM -0400, Don Slutz wrote:
>> 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().
> Yes! Sorry, I hadn't reviewed all of your previous series yet.  :-)
>
>> I did not know that I need to
>> make the CPU class a child of DeviceState.
> You don't. But we plan to do that, eventually, so we can put
> CPU compatibility properties into machine-types.
>
>> 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.
> What I would like to do is: to change the default to 0x40000001 (that's
> the correct value), but make the pc-1.1 and older machine-types keep the
> hypervisor-level=0 default for compatibility.
>
> (But to be able to do that, we need to first make the CPU class a child
> of DeviceState, so that's something to be done later)
>
Now that ([PATCH v5 00/17] Allow changing...):

http://lists.gnu.org/archive/html/qemu-devel/2012-09/msg03810.html

is released, this contains all that is left of the patch set.  So there 
will not be a v3.  This patch set is withdrawn.

    -Don