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Re: [Xen-devel] [PATCH] enable port accesses with (almost) fullregister

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>, "Tian, Kevin" <kevin.tian@xxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] enable port accesses with (almost) fullregister context
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 11 Sep 2006 21:04:50 +0100
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On 11/9/06 8:58 pm, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:

> On 11/9/06 6:24 pm, "Tian, Kevin" <kevin.tian@xxxxxxxxx> wrote:
>> Hi, Keir,
>> Say in the driver domain case, does dom0-only bitmap need to sync with admin
>> bitmaps? Or simply depend on the assumption that dom0 won't use io ports
>> granted to other domains?
> There's no checking of that kind of thing already. Xen will happily allow
> I/O memory and I/O ports to be assigned write access for multiple domains
> simultaneously. It's up to control tools, or a sysadmin, to implement or
> enforce a more sophisticated policy if that is what is wanted.

Maybe I misunderstood the question. If control tools update an admin bitmap
today, then future port accesses by the guest are affected. If this dom0
special bitmap is implemented, it is probably the case that we will not
filter it through dom0's admin bitmap. As you say, we'll assume that special
ports wouldn't be assigned to other domU's anyway.

 -- Keir

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