Re: [Xen-devel] [PATCH v2 2/6] x86/cpuid: Introduce recalculate_xstate()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 17/01/17 15:28, Jan Beulich wrote:
>>>> On 17.01.17 at 16:15, <andrew.cooper3@xxxxxxxxxx> wrote:
>> On 17/01/17 12:52, Jan Beulich wrote:
>>>>>> On 17.01.17 at 12:27, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> @@ -154,6 +152,13 @@ struct cpuid_policy
>>>>              };
>>>>              uint32_t /* b */:32, xss_low, xss_high;
>>>>          };
>>>> +
>>>> +        /* Per-component common state.  Valid for i >= 2. */
>>>> +        struct {
>>>> +            uint32_t size, offset;
>>>> +            bool xss:1, align:1;
>>>> +            uint32_t _res_d;
>>> I see you've decided against an inner union. Should be fine of
>>> course, at least until we have a need to access the full ECX value
>>> by name.
>> Oh - I misinterpreted what you meant then.
>>
>> Did you mean
>>
>> struct {
>>     uint32_t size, offset;
>>     union {
>>         struct {
>>             bool xss:1, align:1;
>>         };
>>         uint32_t c;
>>     };
>>     uint32_t /* d */:32;
>> };
>>
>> Then?
> Yes. But in the end it's up to you which variant to use.

We only write via the xss/align names, and read through raw[].

For now, lets go with mine which is a simpler structure.  We can always
change it if we need to.

~Andrew

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