Re: [Qemu-devel] [PATCH v6 03/16] target-i386: Add cpu object access routines for Hypervisor level.

[Don Slutz <Don@CloudSwitch.Com>]

On 10/10/12 11:40, Andreas Färber wrote:
> Am 10.10.2012 17:22, schrieb Don Slutz:
>> On 10/09/12 15:13, Don Slutz wrote:
>>> On 10/09/12 12:25, Marcelo Tosatti wrote:
>>>> On Mon, Sep 24, 2012 at 10:32:05AM -0400, Don Slutz wrote:
>>>>> +static void x86_cpuid_set_hv_level(Object *obj, Visitor *v, void
>>>>> *opaque,
>>>>> +                                const char *name, Error **errp)
>>>>> +{
>>>>> +    X86CPU *cpu = X86_CPU(obj);
>>>>> +    uint32_t value;
>>>>> +
>>>>> +    visit_type_uint32(v, &value, name, errp);
>>>>> +    if (error_is_set(errp)) {
>>>>> +        return;
>>>>> +    }
>>>>> +
>>>>> +    if (value != 0 && value < 0x40000000) {
>>>>> +        value += 0x40000000;
>>>>> +    }
>>>> Whats the purpose of this? Adds ambiguity.
> [...]
>> This is direct copy with adjustment from x86_cpuid_set_xlevel():
>>
>>      if (value < 0x80000000) {
>>          value += 0x80000000;
>>      }
>>
>> (Pending patch:
>> http://comments.gmane.org/gmane.comp.emulators.qemu/172703 adds this)
> (Any pending patch can be changed ;))
>
>> The adjustment is that 0 is a legal value. See
>> http://lkml.indiana.edu/hypermail/linux/kernel/1205.0/00100.html
>>
>> This does mean that just like xlevel=1 and xlevel=0x80000001 are the
>> same; hypervisor-level=1 and hypervisor-level=0x4000001 are the same.
>> If this is not wanted, I have no issue with removing it.
> I have no strong opinion either way, but if there's only one call site,
> I'd prefer to apply these fixups to user input before setting the
> property and to have the property setter error out on invalid values. I
> consider that cleaner than silently fixing up values inside the setter.
>
> Regards,
> Andreas
>
I find more then one call site.  And one of them is converting the 
predefined x86 cpus (like 486).  So I am not planning on a change.

I have finished up the v7 changes except for this.  I will wait until 
some time tomorrow to send it in case there is more on this topic.
     -Don Slutz