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

[Julien Grall <julien.grall@linaro.org>]

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