Re: [Xen-devel] [PATCH 03 of 16] amd iommu: Add iommu emulation for hvm guest

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 15.12.11 at 15:09, Wei Wang2 <wei.wang2@xxxxxxx> wrote:
> On Thursday 15 December 2011 14:35:55 Tim Deegan wrote:
>> Hi,
>>
>> At 16:29 +0100 on 14 Dec (1323880164), Wei Wang wrote:
>> > +static struct page_info* guest_iommu_get_page(struct list_head *pglist,
>> > +                                              unsigned int entry_size,
>> > +                                              unsigned int pos)
>> > +{
>> > +    int idx;
>> > +    struct list_head *head;
>> > +    struct guest_pages *gpage = NULL;
>> > +
>> > +    idx = (pos * entry_size) >> PAGE_SHIFT;
>> > +    list_for_each( head, pglist )
>> > +    {
>> > +        gpage = list_entry(head, struct guest_pages, list);
>> > +        if ( (--idx) < 0 )
>> > +            break;
>> > +    }
>>
>> Given that you allocate all these elements together, and free them, all
>> together, why not just use an array instead of a linked list?
>>
>> Cheers,
>>
>> Tim.
> The numbers of element might be variant. But array should also work, 
> considering iommu tables has max. length of 2MB, the array length is small.

Small enough so the array would fit in a single page?

Jan


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