Re: [PATCH v2 1/7] x86/boot: Remove verify_cpu() from secondary_startup_64()

[Ingo Molnar <mingo@xxxxxxxxxx>]

* Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> The boot trampolines from trampoline_64.S have code flow like:
> 
>   16bit BIOS                  SEV-ES                          64bit EFI
> 
>   trampoline_start()          sev_es_trampoline_start()       
> trampoline_start_64()
>     verify_cpu()                        |                             |
>   switch_to_protected:    <---------------'                           v
>        |                                                      
> pa_trampoline_compat()
>        v                                                              |
>   startup_32()                
> <-----------------------------------------------'
>        |
>        v
>   startup_64()
>        |
>        v
>   tr_start() := head_64.S:secondary_startup_64()

oh ... this nice flow chart should move into a prominent C comment I think, 
it's far too good to be forgotten in an Git commit changelog.

> Since AP bringup always goes through the 16bit BIOS path (EFI doesn't
> touch the APs), there is already a verify_cpu() invocation.
> 
> Removing the verify_cpu() invocation from secondary_startup_64()
> renders the whole secondary_startup_64_no_verify() thing moot, so
> remove that too.
> 
> Cc: jroedel@xxxxxxx
> Cc: hpa@xxxxxxxxx
> Fixes: e81dc127ef69 ("x86/callthunks: Add call patching for call depth 
> tracking")
> Reported-by: Joan Bruguera <joanbrugueram@xxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

Reviewed-by: Ingo Molnar <mingo@xxxxxxxxxx>

Thanks,

        Ingo