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RE: [Xen-devel] granting access to MSI-X table and pending bit array

To: <yunhong.jiang@xxxxxxxxx>,<konrad.wilk@xxxxxxxxxx>
Subject: RE: [Xen-devel] granting access to MSI-X table and pending bit array
From: "Jan Beulich" <jbeulich@xxxxxxxxxx>
Date: Thu, 05 Aug 2010 18:44:28 +0100
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>>> "Jiang, Yunhong"  07/15/10 10:24 AM >>>
>Will the small window for qemu exists still? QEMU may setup the mapping before 
>the msix_capability_init().

Yes, I think so, as Dom0 still is permitted to map this area writable (revoking 
this requires a qemu fix to be committed at the same time, or a prerequisite 
fix to make qemu map this area read-only, which I think doesn't fit well within 
the MMIO model used there).

>BTW, I'm not sure if mapping as RO this will solve the sharing issue (i.e. the 
>PBA or table entry share with other resource).

Not if the device meets the standard's requirement of these two tables being 
allowed to share a page between them, but not with any other resource.


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