Re: [Xen-devel] [PATCH v13 3/3] iommu: add rmrr Xen command line option for extra rmrrs

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 19.01.17 at 18:44, <elena.ufimtseva@xxxxxxxxxx> wrote:
> On Thu, Jan 19, 2017 at 01:29:15AM -0700, Jan Beulich wrote:
>> >>> On 18.01.17 at 20:56, <elena.ufimtseva@xxxxxxxxxx> wrote:
>> > I am looking at rmrr_identity_mapping where the RMRR paddr get converted
>> > to pfn and then mapped with iommu.
>> > If ( rmrr->end_address & ~PAGE_SHIFT_MASK_4K ) == 0, the while loop
>> >     while ( base_pfn < end_pfn )
>> >  will not map that inclusive end_address of rmrr.
>> > Does it seem wrong?
>> 
>> I don't think so, no. end_pfn is being calculated using
>> PAGE_ALIGN_4K(), i.e. rounding up.
> 
> I mean to say, if the end address is already aligned, then the page wont
> be mapped.

Ah, that would be a problem, but would only affect systems with
non-spec compliant firmware, as the doc says: "The reserved
memory region size (Limit - Base + 1) must be an integer multiple of
4KB", along with requiring the base address to be 4k-aligned.

Jan


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