[Xen-devel] Re: xen dependant on pcpu 0 ?

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 13.10.10 at 16:26, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
> Besides ... returning a bogus address in this piece of code:
> 
>        if ( !dev->domain || !paging_mode_translate(dev->domain) )
>         {
>             struct domain *d = dev->domain;
> 
>             if ( !d )
>                 for_each_domain(d)
>                     if ( !paging_mode_translate(d) &&
>                          (iomem_access_permitted(d, dev->msix_table.first,
>                                                  dev->msix_table.last) ||
>                           iomem_access_permitted(d, dev->msix_pba.first,
>                                                  dev->msix_pba.last)) )
>                         break;
>             if ( d )
>             {
>                 /* XXX How to deal with existing mappings? */
>                 printk("SEIK: err what am i doing here ?? d=%d 
> \n",d->domain_id);
> 
>             }
>         }
> 
> On a freshly booted machine, d seems to be 0 ... that would mean the ( !d ) 
> code path will never be followed since all devices will belong to dom0 at 
> first ?

Not sure what you're trying to say. This code path will not only get
executed on a freshly booted system, but whenever MSI-X gets
first enabled for a device after it having been disabled (perhaps
because of it getting assigned to a guest).

And for the moment Dom0 is still considered an exception (i.e.
may map this space writable), so on initial boot it doesn't matter
whether the device is considered un-owned or owned by Dom0.

Jan


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