Re: [Xen-devel] [RFC PATCH 2/7] iommu: add iommu_lookup_page to lookup guest gfn for a particular IOMMU mapping

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Wed, Feb 17, 2016 at 8:22 PM, Konrad Rzeszutek Wilk
<konrad.wilk@xxxxxxxxxx> wrote:
>> +    {
>> +        *gfn = bfn;
>> +        return 0;
>> +    }
>> +
>> +    if ( !iommu_enabled || !hd->platform_ops ||
>> +            !hd->platform_ops->lookup_page )
>> +        return -ENOMEM;
>
> -ENOMEM ? ENXIO ? Or maybe -ENOSYS for the case when hd->platform_ops
> is not set nor ->lookup_page?

I think ENOTSUPP, perhaps?  ENOMEM means a memory allocation failed
(which it hasn't); ENOSYS means this is an invalid system call (which
it isn't).  ESRCH could be close too, but it seems like that would be
more appropriate when you try to lookup a non-existent BFN.

 -George

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