RE: [Xen-devel] [VTD][PATCH] Use bitmap to solve domain-id limitation issue

["Han, Weidong" <weidong.han@xxxxxxxxx>]

Hi Keir,

I baked a new patch. It removes the mapping list, stores iommu domain id
in struct hvm_iommu instead. In addition, add a spinlock to protect
domain id bitmap. Pls review it. Thanks.

Randy (Weidong)

Keir Fraser wrote:
> Why must a list be walked every time you want to translate
> domid->iommu_id? Wouldn't you be better to store it in struct
> hvm_iommu? 
> 
> Under what lock is the list of domid/iommu_id mappings protected?
> Under what lock is the allocation bitmap protected (if necessary)?
> 
> This patch is definitely in the right direction, I just think it's
> not fully baked yet...
> 
>  -- Keir
> 
> On 29/11/07 13:33, "Han, Weidong" <weidong.han@xxxxxxxxx> wrote:
> 
>> The Capability register reports the domain-id width supported by
>> hardware. For implementations supporting less than 16-bit domainids,
>> unused bits of domain identifier field(87:72) in Context entry are
>> treated as reserved by hardware. For example, for an implementation
>> supporting 4-bit domain-ids, bits 87:76 of this field are treated as
>> reserved. 16 is a small number, overflow is easy to happen. What's
>> more, context-entries programmed with the same domain identifier
>> must always reference the same address translation structure
>> (through the ASR field). So Dom16 will conflict with Dom0, and
>> device assignment fails. 
>> 
>> This patch implements a domaid id bitmap to solve above issue.
>> 
>> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel

Attachment: domid-2.patch
Description: domid-2.patch

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