[Xen-devel] Re: Comments on Xen bug 1732

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 31.01.11 at 13:02, Haitao Shan <maillists.shan@xxxxxxxxx> wrote:
> I am wondering whether we can trust msi->table_base for the moment?

But that's already the case. A warning is issued if it doesn't match
what we read from the BAR, but what comes from Dom0 is being
used. The PBA, which doesn't gets passed up from Dom0, gets
determined by reading the device's config space (and is going to
be zero or close to it when the BAR is blank). Xen itself doesn't
use it for anything but trying to write-protect the corresponding
MFN.

> Simply removing the warnings can of course suppress the symptom. But
> assuming MSIX table at pfn 0 and changing its p2m type are a concern to me.
> But probably this won't trigger anything bad, since this pfn is seldom used?

We should not use MFN zero here (and that really is what I
intended the warnings to catch).

Jan


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