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

[Don Slutz <Don@CloudSwitch.Com>]

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:
>>> These are modeled after x86_cpuid_get_xlevel and x86_cpuid_set_xlevel.
>>>
>>> Signed-off-by: Don Slutz <Don@CloudSwitch.com>
>>> ---
>>>   target-i386/cpu.c |   29 +++++++++++++++++++++++++++++
>>>   1 files changed, 29 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
>>> index 25ca986..451de12 100644
>>> --- a/target-i386/cpu.c
>>> +++ b/target-i386/cpu.c
>>> @@ -1166,6 +1166,32 @@ static void x86_cpuid_set_tsc_freq(Object 
>>> *obj, Visitor *v, void *opaque,
>>>       cpu->env.tsc_khz = value / 1000;
>>>   }
>>>   +static void x86_cpuid_get_hv_level(Object *obj, Visitor *v, void 
>>> *opaque,
>>> +                                const char *name, Error **errp)
>>> +{
>>> +    X86CPU *cpu = X86_CPU(obj);
>>> +
>>> +    visit_type_uint32(v, &cpu->env.cpuid_hv_level, name, errp);
>>> +}
>>> +
>>> +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.
> Will add more info in this commit message.
>    -Don
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Not clear on how to add info in the commit message.

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)

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.

    -Don Slutz