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RE: [Xen-devel] [PATCH] [VTD] Separate VT-d page table from P2M table

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Subject: RE: [Xen-devel] [PATCH] [VTD] Separate VT-d page table from P2M table
From: "Han, Weidong" <weidong.han@xxxxxxxxx>
Date: Mon, 28 Apr 2008 16:08:16 +0800
Cc: "Xu, Anthony" <anthony.xu@xxxxxxxxx>, "Kay, Allen M" <allen.m.kay@xxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "Nakajima, Jun" <jun.nakajima@xxxxxxxxx>
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Thread-topic: RE: [Xen-devel] [PATCH] [VTD] Separate VT-d page table from P2M table

Attached patch removes the shared option, and only supports separated
VT-d page table.

Randy (Weidong)

Keir Fraser wrote:
> On 22/4/08 16:43, "Li, Xin B" <xin.b.li@xxxxxxxxx> wrote:
>>> Then don't allow EPT 2MB mappings for domains which have passthru
>>> devices? 
>> EPT 2M page is already supported while VT-d 2M not, so for we have to
>> seperate the 2 guys if we want to use 2M page in EPT.
>> and of course we share the page tables if both sides use 4K pages.
> Just share the tables and put up with not having 2MB mappings
> available to you if a guest has devices passed through to it? Doesn't
> sound so bad to me, and you can get the performance back down the
> line by fixing the VT-d hardware to understand superpage mappings.
> We're going to end up with a silly number of p2m structures otherwise.
>  -- Keir

Attachment: vtd-sep-2.patch
Description: vtd-sep-2.patch

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