Re: Re: [RFC PATCH v4 0/6] arm64: tlb: add support for TTL feature

[Peter Zijlstra]

On Wed, Mar 25, 2020 at 12:49:45PM +0800, Zhenyu Ye wrote:
> Hi Peter,
> 
> On 2020/3/24 23:01, Peter Zijlstra wrote:
> > On Tue, Mar 24, 2020 at 09:45:28PM +0800, Zhenyu Ye wrote:
> >> In order to reduce the cost of TLB invalidation, the ARMv8.4 TTL
> >> feature allows TLBs to be issued with a level allowing for quicker
> >> invalidation.  This series provide support for this feature. 
> >>
> >> Patch 1 and Patch 2 was provided by Marc on his NV series[1] patches,
> >> which detect the TTL feature and add __tlbi_level interface.
> > 
> > I realy hate how it makes vma->vm_flags more important for tlbi.
> > 
> 
> Thanks for your review.
> 
> The tlbi interfaces only have two parameters: vma and addr. If we
> try to not use vma->vm_flags, we may should have to add a parameter
> to some of these interfaces(such as flush_tlb_range), which are
> common to all architectures.
> 
> I'm not sure if this is feasible, because this feature is only
> supported by ARM64 currently.

Power (p9-radix) also has level dependent invalidation instructions, so
at the very least you can hook them up as well.