Re: [PATCH 4/8] x86/IDT: Rename idt_table[] to bsp_idt[]

[Jan Beulich <jbeulich@xxxxxxxx>]

On 25.02.2025 17:20, Andrew Cooper wrote:
> On 25/02/2025 2:33 pm, Jan Beulich wrote:
>> On 25.02.2025 13:54, Andrew Cooper wrote:
>>> On 25/02/2025 9:00 am, Jan Beulich wrote:
>>>> On 24.02.2025 17:05, Andrew Cooper wrote:
>>>>> Having variables named idt_table[] and idt_tables[] is not ideal.
>>>>>
>>>>> Use X86_IDT_VECTORS and remove IDT_ENTRIES.  State the size of bsp_idt[] 
>>>>> in
>>>>> idt.h so that load_system_tables() and cpu_smpboot_alloc() can use 
>>>>> sizeof()
>>>>> rather than opencoding the calculation.
>>>>>
>>>>> Move the variable into a new traps-init.c, to make a start at splitting
>>>>> traps.c in half.
>>>> Hmm, I'd expect a file of that name to contain only __init code/data, and
>>>> hence for it to be possible to ...
>>>>
>>>>> --- a/xen/arch/x86/Makefile
>>>>> +++ b/xen/arch/x86/Makefile
>>>>> @@ -65,6 +65,7 @@ obj-y += spec_ctrl.o
>>>>>  obj-y += srat.o
>>>>>  obj-y += string.o
>>>>>  obj-y += time.o
>>>>> +obj-y += traps-init.o
>>>> ... use
>>>>
>>>> obj-bin-y += traps-init.init.o
>>>>
>>>> here.
>>> AP bringup and S3 resume will have a rather hard time working if that
>>> were the case.
>>>
>>> Plenty of it does end up being __init, but not all.
>> Hmm, yes. Yet then, taking into consideration what you put in that file
>> right in this series (which there's nothing init-ish about, as the tables
>> are needed until we reboot / shut down / crash), what's the designated
>> pattern for what is to go where?
> 
> Configuring event handling turns out to be pretty disjoint from actual
> event handling, and traps.c is already too complicated.
> 
> If you can suggest a better name than traps-init.c then I'm all ears,
> but I couldn't think of one.
> 
> Other commits I've got in the next batch of cleanup are:
> 
> x86/traps: Move subarch_percpu_traps_init() into traps-init.c
> x86/traps: Move load_system_tables() into traps-init.c
> x86/traps: Simplify early exception setup
> x86/traps: Fold init_idt_traps() and trap_init() into their single callers
> x86/traps: Introduce new init APIs
> x86/traps: Move percpu_traps_init() into traps-init.c
> x86/traps: Move cpu_init() out of trap_init()
> 
> which gives some idea of what's changing, although this isn't complete
> yet.  Even things like LER setup end up moving in here.

traps-setup.c maybe? Just to avoid the "init" in the name.

Jan

> Setting up FRED requires the cmdline, feature scan, and a determination
> of pv_shim, all of which precludes it from being used for early
> exception handling.  Therefore, what I've ended up trying to arrange is:
> 
> 1) early_exception_init() (start of day)
> 2) traps_init() (replaces the current trap_init())
> 3) percpu_traps_init()
> 
> where early_exception_init() is even more simple than what we have
> today, and traps_init() tailcalls percpu_traps_init() to remove some
> duplication we've got.
> 
> ~Andrew