Re: [PATCH 2/3] x86/svm: Enumeration for CET

[Jan Beulich <jbeulich@xxxxxxxx>]

On 27.04.2021 19:47, Andrew Cooper wrote:
> On 27/04/2021 16:53, Jan Beulich wrote:
>> On 26.04.2021 19:54, Andrew Cooper wrote:
>>> @@ -497,7 +501,9 @@ struct vmcb_struct {
>>>      u64 rip;
>>>      u64 res14[11];
>>>      u64 rsp;
>>> -    u64 res15[3];
>>> +    u64 _msr_s_cet;             /* offset 0x400 + 0x1E0 - cleanbit 12 */
>>> +    u64 _ssp;                   /* offset 0x400 + 0x1E8   | */
>>> +    u64 _msr_isst;              /* offset 0x400 + 0x1F0   v */
>>>      u64 rax;
>>>      u64 star;
>>>      u64 lstar;
>> Any reason for the leading underscores, when none of the neighboring
>> fields have such?
> 
> Yes - they're covered by a cleanbit, and for better or worse, this is
> our style.

The underscore prefixes are, to my understanding, there only to
emphasize that the fields shouldn't be accessed directly, but ...

>> Did you perhaps mean to add VMCB_ACCESSORS()
>> instances for them?
> 
> TBH, I opencoded the cleanbit handling because I thoroughly hate that
> entire infrastructure.

... via this (or something with similar abstracting effect). So
for any fields you mean to access directly they imo shouldn't be
there. I particularly don't view them as indicators of being
covered by cleanbits (if the respective accessors aren't used).

Jan