Re: [Xen-devel] [PATCH 07/14] xen: balloon: do not update stage 1 pagetable for autotranslated guests

[Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>]

On Fri, 5 Oct 2012 13:05:01 +0100
Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> wrote:

> On Thu, 4 Oct 2012, Ian Campbell wrote:
> > This is unnecessary (since the page will be removed from the p2m)
> > and can be tricky if the page is in the middle of a superpage, as
> > it is on ARM.
> > 
> 
> I think that this patch is correct. I'll leave to Konrad whether we
> should carry the original incorrect PVH patch and this separate fix or
> just merge the two of them.
> 
> 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > ---
> > Also effects PVH but in a benign way I think.
> >
> >  drivers/xen/balloon.c |   23 +++--------------------
> >  1 files changed, 3 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> > index 7885a19..1b56ae0 100644
> > --- a/drivers/xen/balloon.c
> > +++ b/drivers/xen/balloon.c
> > @@ -357,15 +357,7 @@ static enum bp_state
> > increase_reservation(unsigned long nr_pages)
> > BUG_ON(!xen_feature(XENFEAT_auto_translated_physmap) &&
> > phys_to_machine_mapping_valid(pfn)); 
> > -           if (xen_pv_domain() && 
> > -               xen_feature(XENFEAT_auto_translated_physmap)) {
> > -                   /* PVH: we just need to update native page
> > table */
> > -                   pte_t *ptep;
> > -                   unsigned int level;
> > -                   void *addr = __va(pfn << PAGE_SHIFT);
> > -                   ptep = lookup_address((unsigned long)addr,
> > &level);
> > -                   set_pte(ptep, pfn_pte(pfn, PAGE_KERNEL));
> > -           } else
> > +           if (!xen_feature(XENFEAT_auto_translated_physmap))
> >                     set_phys_to_machine(pfn, frame_list[i]);
> >  
> >             /* Link back into the page tables if not highmem.
> > */ @@ -427,21 +419,12 @@ static enum bp_state
> > decrease_reservation(unsigned long nr_pages, gfp_t gfp) 
> >             scrub_page(page);
> >  
> > -           if (xen_pv_domain() && !PageHighMem(page)) {
> > -                   if
> > (xen_feature(XENFEAT_auto_translated_physmap)) {
> > -                           unsigned int level;
> > -                           pte_t *ptep;
> > -                           void *addr = __va(pfn <<
> > PAGE_SHIFT);
> > -                           ptep = lookup_address((unsigned
> > long)addr, 
> > -                                                   &level);
> > -                           set_pte(ptep, __pte(0));
> > -
> > -                   } else {
> > +           if (xen_pv_domain() && !PageHighMem(page) &&
> > +               !xen_feature(XENFEAT_auto_translated_physmap))
> > { ret = HYPERVISOR_update_va_mapping(
> >                                     (unsigned long)__va(pfn <<
> > PAGE_SHIFT), __pte_ma(0), 0);
> >                             BUG_ON(ret);
> > -                   }
> >             }
> >     }
> >  
> > -- 
> > 1.7.2.5
> > 


I've made this change in my tree also. So, its good for PVH also. 

thanks
Mukesh


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