| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
[Xen-devel] Re: [XEN-IOMMU] Proposal of DMA protection/isolation support
|
To: |
Wei Wang2 <wei.wang2@xxxxxxx> |
|
Subject: |
[Xen-devel] Re: [XEN-IOMMU] Proposal of DMA protection/isolation support |
|
From: |
Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> |
|
Date: |
Wed, 16 Jan 2008 18:25:59 +0000 |
|
Cc: |
muli@xxxxxxxxxx, "Dannowski, Uwe" <Uwe.Dannowski@xxxxxxx>, "Hohmuth, Michael" <Michael.Hohmuth@xxxxxxx>, "Woller, Thomas" <thomas.woller@xxxxxxx>, iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, elsie.wahlig@xxxxxxx, amit.shah@xxxxxxxxxxxx |
|
Delivery-date: |
Wed, 16 Jan 2008 10:26:20 -0800 |
|
Envelope-to: |
www-data@xxxxxxxxxxxxxxxxxx |
|
In-reply-to: |
<1200503754.4026.108.camel@xxxxxxxxxxxx> |
|
List-help: |
<mailto:xen-devel-request@lists.xensource.com?subject=help> |
|
List-id: |
Xen developer discussion <xen-devel.lists.xensource.com> |
|
List-post: |
<mailto:xen-devel@lists.xensource.com> |
|
List-subscribe: |
<http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe> |
|
List-unsubscribe: |
<http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe> |
|
Sender: |
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
|
Thread-index: |
AchYbT20fA4yXsRgEdyOUgAWy6hiGQ== |
|
Thread-topic: |
[XEN-IOMMU] Proposal of DMA protection/isolation support |
|
User-agent: |
Microsoft-Entourage/11.3.6.070618 |
On 16/1/08 17:15, "Wei Wang2" <wei.wang2@xxxxxxx> wrote:
>> Local pages could always be mapped into the iommu, and only remote pages
>> would need to be temporarily mapped via the gnttab hooks.
> I remembered that vtd patch used to hook page assignment to for this,
> but it was soon replaced with statical 1:1 mapping. Could you suggest me
> how to trace local page changes instead of mapping whole the physical
> ram?
alloc_domheap_pages() if you want to map MFNs. populate_physmap() if you
want to map PFNs. There might be a few other places to hook also but I
expect they're the main ones.
>> 2) When dma layer is invoked to prepare a bus address for native block
>>> device driver. It would be better to have a "hypervisor-aware" dma layer
>>> which always maps virtual address to bus address via hypercall.
>>> __gnttab_dma_map_page() might be a good place to trigger this new
>>> hypercall. Both remote and local pages can be mapped by this way.
>>
>> An extra hypercall here will likely hurt performance.
> I have implemented a prototype for this which removes 1:1 mapping and invoke a
> hypercall for
> dma mapping. Since block driver uses dma_map_sg heavily which is easy to
> batch, I have not seen dramatic performance loss.
It's hard to slow down block-device accesses. What does it do to CPU usage
and max bandwidth on a multi-gigabit NIC?
-- Keir
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home