Re: [Xen-devel] [RFC PATCH 2/3] arch, arm32: add the XEN_DOMCTL_memory_mapping hypercall

[Arianna Avanzini <avanzini.arianna@xxxxxxxxx>]

On 03/04/2014 04:08 AM, Julien Grall wrote:
> Hello Eric,
> 
> On 04/03/14 02:06, Eric Trudeau wrote:
>> Last I checked, map_mmio_regions takes paddr_t, not frame numbers.
> 
> Right.
> 

Thank you both, I have tried to fix by using the correct conversion macro.

>> Beware:  I found that map_mmio_regions was off by one page unless I changed
>> "gfn + nr_mfns - 1" to "gfn + nr_mfns".
>> This may have been fixed in more recent upstream code.
> 
> That makes me think, map_mmio_regions is buggy if the range is not correctly
> aligned. For instance:
> 
> start_gaddr = 0x1001 and end_gaddr = 0x2001, we only map 0x1000-0x2000 to the
> domain.
> 
> The problem is the same with p2m_populate_ram (even if I doubt that RAM range 
> is
> not page-aligned).
> 
> I see 2 solutions to fix it:
>     - Change map_mmio_regions prototype to use frame is instead address.
>         - Aligned the input addresses.
> 
> IHMO, the former seems to be better, at least it avoid developer to discover
> that some bits was mapped under his feet.
> 

Sorry if I intrude here, thank you for pointing that out. As of now I have tried
to simply pass aligned addresses to map_mmio_regions() when it is invoked by the
memory_mapping hypercall.
Sorry for the additional question, do you think that it would be appropriate to
add to the series a patch implementing one of the above-described solutions (the
one believed to be better)?


> Ian, do you have any opinion?
> 
> Regards,
> 


-- 
/*
 * Arianna Avanzini
 * avanzini.arianna@xxxxxxxxx
 * 73628@xxxxxxxxxxxxxxxxxxx
 */

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