Re: [Xen-devel] [PATCH 03/38] arm: handy function to print a walk of a domain's p2m.

[Tim Deegan <tim@xxxxxxx>]

At 13:26 +0100 on 07 Jun (1339075605), Ian Campbell wrote:
> On Thu, 2012-06-07 at 09:49 +0100, Tim Deegan wrote:
> > At 15:39 +0000 on 01 Jun (1338565172), Ian Campbell wrote:
> > > Useful for debug but not actually used in this patch.
> > > 
> > > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > > ---
> > >  xen/arch/arm/p2m.c         |   34 ++++++++++++++++++++++++++++++++++
> > >  xen/include/asm-arm/page.h |    1 +
> > >  2 files changed, 35 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > > index 4f624d8..fdbecbc 100644
> > > --- a/xen/arch/arm/p2m.c
> > > +++ b/xen/arch/arm/p2m.c
> > > @@ -5,6 +5,40 @@
> > >  #include <xen/domain_page.h>
> > >  #include <asm/flushtlb.h>
> > >  
> > > +void dump_p2m_lookup(struct domain *d, paddr_t addr)
> > > +{
> > > +    struct p2m_domain *p2m = &d->arch.p2m;
> > > +    lpae_t *first = NULL, *second = NULL, *third = NULL;
> > > +
> > > +    printk("dom%d IPA %#016llx\n", d->domain_id, addr);
> > > +
> > > +    first = __map_domain_page(p2m->first_level);
> > > +    printk("1ST[%#03llx] = %#016llx\n",
> > > +           first_table_offset(addr),
> > > +           first[first_table_offset(addr)].bits);
> > > +    if ( !first[first_table_offset(addr)].p2m.valid ||
> > > +         !first[first_table_offset(addr)].p2m.table )
> > > +        goto done;
> > > +
> > > +    second = map_domain_page(first[first_table_offset(addr)].p2m.base);
> > > +    printk("2ND[%#03llx] = %#016llx\n",
> > > +           second_table_offset(addr),
> > > +           second[second_table_offset(addr)].bits);
> > > +    if ( !second[second_table_offset(addr)].p2m.valid ||
> > > +         !second[second_table_offset(addr)].p2m.table )
> > > +        goto done;
> > > +
> > > +    third = map_domain_page(second[second_table_offset(addr)].p2m.base);
> > > +    printk("3RD[%#03llx] = %#016llx\n",
> > > +           third_table_offset(addr),
> > > +           third[third_table_offset(addr)].bits);
> > > +
> > > +done:
> > > +    if (third) unmap_domain_page(third);
> > > +    if (second) unmap_domain_page(second);
> > > +    if (first) unmap_domain_page(first);
> > > +}
> > 
> > Can this be unified with dump_pt_walk?
> 
> Not all that easily, mainly because dump_pt_walk walks xenheap pages
> (which don't need mapping) while dump_p2m_walk dumps domheap pages
> (which need mapping as we go). I probably could write something generic
> enough but I fear that it would be a mass of if's.

Is there any harm in mapping xenheap pages?  Since this is only invoked
on error paths, we don't particularly need it to be fast. 

Tim.

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