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

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 01.02.11 at 06:48, Haitao Shan <maillists.shan@xxxxxxxxx> wrote:
> What I am thinking about here is:
> 1> Given a BDF, how can Xen determine whether it is a VFs?
> 2> If it is really a VF, how can Xen find its PF? For example, if a VF looks
> like 07:03:0, its PF might be 07:00.0 or 06:00.0 ...
> Perhaps a little assist from Dom0 would be very good.

Getting away without assistance from Dom0 would be much
preferred, but input from your SR-IOV engineers would be
needed on how (if at all) this may be achieved.

> Another question: What would the purpose of your patch be? I mean, you are
> trying to remove MSIX table access right for DomUs, or you are also aiming
> at removing msi->table_base from the trust chain so that guests cannot pass
> arbitrary address down to Xen?

No, passing down the address from Dom0 is fine, but given that
we have to use an alternative approach (reading config space) to
determine the PBA address, it seemed rather reasonable (proven
by what we now see) to verify the value as passed up by Dom0
matches what we would calculate on our own (to provide a hint
at whether the PBA address determination needs any fixing,
which we now know it does).

Jan


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