On Thu, Sep 04, 2014 at 10:25:43AM -0700, Mario Smarduch wrote:
> On 09/03/2014 08:29 PM, wanghaibin wrote:
> > On 2014/9/4 7:01, Mario Smarduch wrote:
> >
> >> On 09/02/2014 07:42 PM, wanghaibin wrote:
> >>> On 2014/8/27 8:04, Mario Smarduch wrote:
> >>>
[...]
> >>>
> >>>
> >>> About CONFIG_ARM , I suggest cancle this limmit..
> >>> I just implement a few interfaces for ARM64 , and tested this patch using VNC, it's work.
> >>>
> >> Yes I was planing to do that once ARMv7 and generic/arch split for
> >> dirty log and tlb flush functions are settled. I realize at this time
> >> ARMv8 just needs it's own tlb flush and it's done. But I need a strong
> >> test case before claiming ARMv8 support
> >>
> >> I have some ideas on testing it but migration is probably most
> >> reliable and the only use case really.
> >>
> >> Can you elaborate on your test environment for ARMv8 (you could
> >> email off-line if too long, also thanks for testing!).
I don't mind merging this code for ARMv7 only. For sure, Mario you
would need to test your setup with ARMv8 carefully before we could merge
this for v8, and we should revisit the pud_huge considerations for
ARMv8, although I suspect we're alright given we have similar code in
clear_pud_entry().
> >>
> >>>
> >>> I think this code should be :
> >>>
> >>> if (!pud_none(*pud)) { /* check the *pud valid first */
> >>> BUG_ON(kvm_pud_huge(*pud));
> >>> stage2_wp_pmd_range(pud, addr, next);
> >>> }
> >>
> >> I may be missing something here but not sure how the update improves
> >> anything? Definitely follow-up if I'm off on this.
> >>
[...]
> >
> > So, maybe this problem is that:
> > the first: we should check the *pud is valid/none or not.
> > the second: check the *pud is huge or not.
> I see check for huge pud only if pud is not NULL, sounds good.
Yes, please make this change so this doesn't bite us later when we add
ARMv8 support (whenever that is, now or later).
>
> You also bring up a use case for dirty page logging (other then
> migration), it appears QEMU VNC server uses it for screen updates
> on client.
>
It would be good to test the v7 path with this as well if possible.
-Christoffer
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