Re: [Xen-devel] netif & grant tables

[Stefan Berger <stefanb@xxxxxxxxxx>]

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 07/02/2005 11:34:58 AM:

> > It could be done implicitly, meaning that if you give a domain a 
backend
> > (netif/blkif), that privilege flag will automatically be set by XEN-D 
and
> > used when creating the domain, or explicitly where one specifies the
> > flag(s) to set in the VM config file.
> 
> Doing it implicitly would probably be sensible.
> 
> > From what I can see this does not work anymore - I used to do that 
also.
> > Passing a PCI device to a partition results in an error since the
> > xc_physdev_pci_access_modify call ends in an error.
> 
> Assigning PCI devices is broken in unstable at the moment.  It'll be 
coming 
> back at some stage.
> 
> > I am not sure how 'privilege' is defined.
> 
> Very coarsely at present: IIRC right now domain who's got access to a 
PCI 
> device is as privileged as dom0.  This means they're allowed to map 
memory of 
> other domains, do dom0 ops, etc.
> 
> Grant tables will enable us to deprivilege guests somewhat, then we'll 
split 
> privileges down into more fine-grained capabilities.
> 
Setting the privileged bit in a user domain gets grant tables to work: 
should this bit be set for those kind of domains or rather the IS_PRIV() 
test be removed from the call path which basically would allow all user 
domains to do mapping by default?

    Stefan

> Cheers,
> Mark
> 
> > The privilege does so far not 
> > only mean to do dom 0 ops, but seems to also limit guest domains of 
doing
> > other things - like the backend problem I see. I agree, though, that 
for
> > grant table support a backend should not need privileges.
> >
> > > Cheers,
> > > Mark
> >
> > Cheers,
> >    Stefan
> 
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