Re: [PATCH V2] arm64: tlbflush: avoid writing RES0 bits

[Will Deacon]

On Tue, Mar 27, 2018 at 08:03:07PM -0500, Shanker Donthineni wrote:
> On 03/27/2018 12:36 PM, Will Deacon wrote:
> > On Tue, Mar 27, 2018 at 09:53:16AM -0500, Shanker Donthineni wrote:
> >>>> @@ -154,8 +163,8 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
> >>>>           return;
> >>>>       }
> >>>>   -    start = asid | (start >> 12);
> >>>> -    end = asid | (end >> 12);
> >>>> +    start = __TLBI_VADDR(start, asid);
> >>>> +    end = __TLBI_VADDR(end, asid);
> > 
> > Can you test this bit too, please? ;)
> > 
> 
> I've verified the basic boot functionality on QDF2400 platform. But I can see now
> after your comments, it leads to TLB conflicts because of ASID is truncated to zero
> due to two times 48bit shift.     
> 
> Thanks for catching this one.

I just noticed it during review. In general, if you're making changes
relating to virtual memory stuff I'd *strongly* advise you to do more
than a basic boot test. It's amazing how much appears to run fine when
stuff like TLB invalidation is completely broken.

Anyway, thanks for turning around a new version so quickly.

Will