Re: [PATCH v5 1/4] target/i386: add missing vmx features for several CPU models

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 7/13/2020 3:23 PM, Chenyi Qiang wrote:
> 
> 
> On 7/11/2020 12:48 AM, Eduardo Habkost wrote:
>> On Fri, Jul 10, 2020 at 09:45:49AM +0800, Chenyi Qiang wrote:
>>>
>>>
>>> On 7/10/2020 6:12 AM, Eduardo Habkost wrote:
>>>>
>>>> I'm very sorry for taking so long to review this.  Question
>>>> below:
>>>>
>>>> On Fri, Jun 19, 2020 at 03:31:11PM +0800, Chenyi Qiang wrote:
>>>>> Add some missing VMX features in Skylake-Server, Cascadelake-Server 
>>>>> and
>>>>> Icelake-Server CPU models based on the output of Paolo's script.
>>>>>
>>>>> Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
>>>>
>>>> Why are you changing the v1 definition instead adding those new
>>>> features in a new version of the CPU model, just like you did in
>>>> patch 3/4?
>>>>
>>>
>>> I suppose these missing vmx features are not quite necessary for 
>>> customers.
>>> Just post it here to see if they are worth being added.
>>> Adding a new version is reasonable. Is it appropriate to put all the 
>>> missing
>>> features in patch 1/4, 3/4, 4/4 in a same version?
>>
>> Yes, it would be OK to add only one new version with all the new
>> features.
>>
> 
> During the coding, I prefer to split the missing vmx features into a new 
> version of CPU model, because the vmx features depends on CPUID_EXT_VMX. 
> I think It would be better to distinguish it instead of enabling the vmx 
> transparently. i.e.
> {
>      .version = 4,
>      .props = (PropValue[]) {
>          { "sha-ni", "on" },
>          ... ...
>          { "model", "106" },
>                  { /* end of list */ }
>      },
> },
> {
>      .version = 5,
>      .props = (PropValue[]) {
>          { "vmx", "on" }

Chenyi,

This is not we have discussed. I prefer to changing the logic of 
versioned CPU model to not add the features in versioned CPU model to 
env->user_features[]. They're not supposed to be added to 
env->user_features[] since they're not set by user through -feature/+feature

Eduardo,

What do you think?