Re: [Xen-devel] [PATCH] xen: arm: invalidate caches after map_domain_page done

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 01/08/14 12:37, Andrii Tseglytskyi wrote:
> > The page you are trying to map belongs to a guest, right? When the guest
> > writes data in this page. Does it map with cacheable attribute or not? I
> > suspect no.
> Hard to say. This page is allocated using usual kernel API such as
> kmalloc(). Then its pfn is stored in MMU 1-st level translation
> pagetable.
If it's allocated from kmalloc then the page is allocated with cacheable 
attribute.
> Before storing - kernel driver flush corresponding cache ranges.
Clean and invalidate the cache, right?

> After
> this - remoteproc_iommu framework translates pfns to mfns.
> So - I would expect that after map_domain_page() function call all
> data will be valid.
Actually with your explanation me too. :)

I'm run out of idea. Maybe Ian or Stefano have any clue.

> > I think your current problem is the cache contains stall data. In this case
> > you have to only invalidate the cache.
> May work. But it looks like new helper should be introduced in this
> case. I see that only clean_and_invalidate_xen_dcache_va_range API is
> present, no standalone API for invalidating only.
You can add a new helper. I suspect it will be necessary sooner or later 
in other places.
Regards,

--
Julien Grall

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