Re: [Xen-devel] [PATCH v6 06/11] xen, x86: factor out map and unmap from the memory_mapping DOMCTL

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.04.14 at 18:14, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 21/04/2014 14:44, Arianna Avanzini wrote:
>> --- a/xen/include/asm-x86/p2m.h
>> +++ b/xen/include/asm-x86/p2m.h
>> @@ -32,6 +32,18 @@
>>   #include <asm/mem_sharing.h>
>>   #include <asm/page.h>    /* for pagetable_t */
>>   
>> +/* Map MMIO regions in the p2m: start_gfn and end_gfn is the range, 
>> inclusive
>> + * of the end_gfn frame number, in the guest physical address space to map,
>> + * starting from the machine frame number mfn. */
>> +int map_mmio_regions(struct domain *d,
>> +                     unsigned long start_gfn,
>> +                     unsigned long end_gfn,
>> +                     unsigned long mfn);
>> +int unmap_mmio_regions(struct domain *d,
>> +                       unsigned long start_gfn,
>> +                       unsigned long end_gfn,
>> +                       unsigned long mfn);
>> +
>>   extern bool_t opt_hap_1gb, opt_hap_2mb;
>>   
>>   /*
> 
> Given that you are changing all of this, please please take the time to 
> change these functions (and others in the series, where appropriate) to 
> take parameters more like (struct domain *d, unsigned long gfn, unsigned 
> long mfn, unsigned long count)
> 
> With a count parameter as opposed to a start/end pair, there can be no 
> confusion regarding inclusive/exclusive ranges, or at which point to 
> subtract 1.  It will also resemble the information in the hypercall, and 
> avoids needing to recalculate nr_mfns everywhere.

Ian had asked for this too. But I'm not sure - neither a [start,end)
pair nor start plus count can express the full address range; only
a [start,end] pair can. That said, I realize that we're not going to
ever see a (reasonable) use of these functions covering the entire
address space...

Jan


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