Re: [Xen-devel] [PATCH] xen/arm: Allow balooning working with 1:1 memory mapping

[Julien Grall <julien.grall@xxxxxxxxxx>]

Ping, any input for X86 maintainers (Keir, Jan)?

On 11/14/2013 04:18 PM, Julien Grall wrote:
> On 11/14/2013 03:34 PM, Stefano Stabellini wrote:
> > On Thu, 14 Nov 2013, Julien Grall wrote:
> > > With the lake of iommu, dom0 must have a 1:1 memory mapping for all
> > > these guest physical address. When the ballon decides to give back a
> > > page to the kernel, this page must have the same address as previously.
> > > Otherwise, we will loose the 1:1 mapping and will break DMA-capable
> > > device.
> > >
> > > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > > CC: Keir Fraser <keir@xxxxxxx>
> > > CC: Jan Beulich <jbeulich@xxxxxxxx>
> > > ---
> > >   xen/common/memory.c | 42 ++++++++++++++++++++++++++++++++++++++++--
> > >   1 file changed, 40 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/xen/common/memory.c b/xen/common/memory.c
> > > index 50b740f..df36d43 100644
> > > --- a/xen/common/memory.c
> > > +++ b/xen/common/memory.c
> > > @@ -28,6 +28,9 @@
> > >   #include <public/memory.h>
> > >   #include <xsm/xsm.h>
> > >   #include <xen/trace.h>
> > > +#ifdef CONFIG_ARM
> > > +#include <asm/platform.h>
> > > +#endif
> > >
> > >   struct memop_args {
> > >       /* INPUT */
> > > @@ -90,7 +93,7 @@ static void increase_reservation(struct memop_args *a)
> > >
> > >   static void populate_physmap(struct memop_args *a)
> > >   {
> > > -    struct page_info *page;
> > > +    struct page_info *page = NULL;
> > >       unsigned long i, j;
> > >       xen_pfn_t gpfn, mfn;
> > >       struct domain *d = a->domain;
> > > @@ -122,7 +125,33 @@ static void populate_physmap(struct memop_args *a)
> > >           }
> > >           else
> > >           {
> > > -            page = alloc_domheap_pages(d, a->extent_order,
> > > a->memflags);
> > > +#ifdef CONFIG_ARM
> > > +            if ( d == dom0 &&
> > > platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
> > > +            {
> > > +                mfn = gpfn;
> > > +                if (!mfn_valid(mfn))
> > > +                {
> > > +                    gdprintk(XENLOG_INFO, "Invalid mfn
> > > 0x%"PRI_xen_pfn"\n",
> > > +                             mfn);
> > > +                    goto out;
> > > +                }
> > > +
> > > +                page = mfn_to_page(mfn);
> > > +                if ( !get_page(page, d) )
> > > +                {
> > > +                    gdprintk(XENLOG_INFO,
> > > +                             "mfn 0x%"PRI_xen_pfn" doesn't belong to
> > > dom0\n",
> > > +                             mfn);
> > > +                    goto out;
> > > +                }
> > > +                put_page(page);
> > > +            }
> > > +            else
> > > +#endif
> > I don't know if the x86 maintainers would like that, but I would prefer
> > to remove the ifdef CONFIG_ARM.
> > You just need to define a new function called is_dom0_mapped_11, that
> > always returns false on x86 and on ARM is implemented by d == dom0 &&
> > platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11).
> > Then you can use it on common code.
> With this solution, it's less clear that it's ARM specific code. We are
> introducing a workaround that will never be used on x86.
>
> I would wait an opinion from other maintainers before sending a new
> version of this patch.
--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel