Re: [PATCH] add tlbi=off to disable INVLPGB

[David Laight <david.laight.linux@gmail.com>]

On Fri, 31 Jul 2026 10:46:56 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> On Thu, Jul 30, 2026 at 11:24:39AM -0700, Borislav Petkov wrote:
> > On Thu, Jul 30, 2026 at 07:31:04PM +0200, Peter Zijlstra wrote:  
> > > But also, nah:
> > > 
> > >   https://support.arm.com/documentation/dui0802/b/A64-General-Instructions/TLBI
> > > 
> > > "TLBI - TLB invalidate operation."  
> > 
> > Yap, that's what I meant.
> >   
> > >   tlbi={ipi,broadcast}
> > > 
> > > Anyway, INVLPGB stands for INVaLidate PaGe Broadcast, ain'ted that hard
> > > :-) Also, you know who to complain to for that instruction :-)  
> > 
> > Too late for that. :)
> > 
> > "tlbi=broadcast" is a bit much to type: imagine you're hunched over some box
> > in the server room, like Spiderman, crouching between racks and balancing the
> > keyboard on some old pile of cables... :-P  
> 
> There is IPMI and other fancy remote management stuff these days. There
> is no reason to suffer hearing loss for entering server rooms anymore
> :-)

The real problem is typing while wearing ski gloves...

	David

> 
> > So how about shorter:
> > 
> > "tlbi=bcast"
> > "tlbi=ipi"
> > 
> > ?
> > 
> > We probably won't need to write "bcast" at all, actually, because that would
> > be the default. So "tlbi=ipi" only. Yeah, that's good.  
> 
> Didn't we have a case where INVLPGB was disabled due to firmware or
> something? I was thinking tlbi=broadcast could be used to force enable
> it or something.
> 
> Anyway, if that case don't exist, then yeah.
>