Re: [PATCH v2 2/4] x86/mm/64: Flush global TLB on AP bringup

[Joerg Roedel]

On Wed, Sep 29, 2021 at 08:09:38AM -0700, Dave Hansen wrote:
> On 9/29/21 7:54 AM, Joerg Roedel wrote:
>
> > +	__flush_tlb_all();
> >  }
> 
> Is there a reason to do this flush here as opposed to doing it closer to
> the CR3 write where we switch away from trampoline_pgd?  cr4_init()
> seems like an odd place.

Yeah, the reason is that global flushing is done by toggling CR4.PGE and
I didn't want to do that before CR4 is set up.

The CR3 switch away from the trampoline_pgd for secondary CPUs on x86-64
happens in head_64.S already. I will add some asm to do a global flush
there right after the CR3 switch. Secondary CPUs are already on kernel
virtual addresses at this point.


	Joerg