Re: [Xen-devel] [PATCH 1/2] x86/paging: Update paging_mark_dirty() to use mfn_t

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Dec 14, 2016 at 03:28:49PM +0000, Andrew Cooper wrote:
> On 14/12/16 15:13, Jan Beulich wrote:
> >>>> On 14.12.16 at 15:26, <andrew.cooper3@xxxxxxxxxx> wrote:
> >> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> >> ---
> >> CC: Jan Beulich <JBeulich@xxxxxxxx>
> >> CC: Tim Deegan <tim@xxxxxxx>
> >> CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> >> CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> >> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> >> CC: Julien Grall <julien.grall@xxxxxxx>
> >>
> >> The one use of paging_mark_dirty() in common/tmem shows that TMEM currently
> >> wont compile for ARM.
> > I don't understand: It builds prior to this change, so why would it
> > stop building afterwards? Without this remark I'd have given my
> > R-b ...
> 
> Oh.  cli_{get,put}_page() are stubbed to ASSERT(0) on ARM, which
> restricts the paging_mark_dirty() call to !ARM.
> 
> The history is weird here.  The last change here was you taking out the
> __ia64__ code.
> 
> I can't work out why they should be stubbed separately; there is nothing
> overly x86-specific in them.
> 
> Konrad: Any ideas?

My recollection was that nobody had tried tmem under ARM and it made
it just easier to bypass it until the security audit is completed.

But ARM is the perfect candidate for tmem.. I did have enabling tmem
on ARM on my TODO list but it is below migration. Hm.

I am with changes that look "OKish" to the tmem and then fixing
them when I get my hands on enabling tmem on ARM.

> 
> ~Andrew

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