Re: [Xen-devel] [PATCH v5 3/4] xen: implement guest_physmap_pin_range and guest_physmap_unpin_range

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 10 Sep 2013, Ian Campbell wrote:
> On Mon, 2013-09-09 at 17:06 +0100, Stefano Stabellini wrote:
> >  
> > +static int pin_one_pte(lpae_t *ptep, void *arg, int level)
> > +{
> > +    lpae_t pte = *ptep;
> > +    ASSERT(level == 3);
> > +
> > +    if ( pte.p2m.avail & P2M_DMA_PIN )
> > +        return -EBUSY;
> > +    pte.p2m.avail |= P2M_DMA_PIN;
> > +    write_pte(ptep, pte);
> > +    return 0;
> > +}
> > +
> > +int guest_physmap_pin_range(struct domain *d,
> > +                            xen_pfn_t gpfn,
> > +                            unsigned int order)
> > +{
> > +    return p2m_walker(d, gpfn << PAGE_SHIFT, order,
> > +                      pin_one_pte, NULL);
> 
> Did we not also discuss accounting and limits on the amount of memory a
> guest can lock down?
 
I am thinking to allow hardware domains (is_hardware_domain(d)) to pin
any number of pages, while preveting any other domains from doing it.

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