Re: [PATCH v2 2/2] xen/domain: rewrite emulation_flags_ok()

[Jan Beulich <jbeulich@xxxxxxxx>]

On 21.05.2025 00:38, dmkhn@xxxxxxxxx wrote:
> On Tue, May 20, 2025 at 05:24:33PM +0200, Jan Beulich wrote:
>> On 16.05.2025 04:29, dmkhn@xxxxxxxxx wrote:
>>> --- a/xen/arch/x86/include/asm/domain.h
>>> +++ b/xen/arch/x86/include/asm/domain.h
>>> @@ -494,6 +494,12 @@ struct arch_domain
>>>                                   X86_EMU_PIT | X86_EMU_USE_PIRQ |       \
>>>                                   X86_EMU_VPCI)
>>>
>>> +/* User-selectable features. */
>>> +#define X86_EMU_OPTIONAL        (X86_EMU_USE_PIRQ)
>>> +
>>> +#define X86_EMU_BASELINE        (X86_EMU_ALL & ~(X86_EMU_VPCI | \
>>> +                                                 X86_EMU_OPTIONAL))
>>
>> That is, VPCI is neither baseline nor optional. Certainly at least strange.
> 
> IMO, X86_EMU_OPTIONAL should include both VPCI and PIRQ.
> 
> But that will be a behavior change: AFAIU, VPCI is injected implicitly for 
> dom0
> case only, "default" xl toolstack currently excludes VPCI for HVM domains.
> 
> Do I understand it correctly that "BASELINE" in the symbol name is a concern?

It's not the word by itself. _If_ we want to have such symbols (which I had put
under question before), they need to be named to accurately reflect the purpose.
Imo with the names chosen an implication is that the two are non-overlapping,
while when combined yield the full set of flags.

Jan