Re: [Xen-devel] [PATCH] xen: return a per-mapping error from XENMEM_add_to_physmap_range.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Jan 16, 2013 at 02:28:51PM +0000, Ian Campbell wrote:
> Any Acks/Nacks?

I took the Linux patch and applied it to my stable/pvh... something
already.

> 
> This touches both ARM and x86 (although x86 only notionally until the
> PVH stuff is merged).
> 
> On Fri, 2013-01-04 at 14:03 +0000, Ian Campbell wrote:
> > Since ARM and PVH dom0 kernel use this to map foreign domain pages
> > they could in the future hit paged out or shared pages etc and
> > therefore need to propagate which frames are -ENOENT and which failed
> > for some other reason.
> > 
> > We have not yet released a version of Xen with this particular
> > hypercall subop so we can change the interface without worrying about
> > compatibility (I think/hope).
> > 
> > This would be used by the privcmd driver, in particular it relates to
> > Mats' patch "improve performance of MMAPBATCH_V2."
> > 
> > NB I have only implemented the ARM side since the PVH side isn't in
> > tree yet.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Cc: Mats Petersson <mats.petersson@xxxxxxxxxx>
> > Cc: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx>
> > Cc: Jan Beulich <JBeulich@xxxxxxxx>
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > Cc: tim@xxxxxxx
> > Cc: stefano.stabellini@xxxxxxxxxx
> > Cc: keir@xxxxxxx
> > ---
> >  xen/arch/arm/mm.c           |    4 ++++
> >  xen/include/public/memory.h |    8 +++++++-
> >  2 files changed, 11 insertions(+), 1 deletions(-)
> > 
> > diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> > index d97b3ea..945e7ac 100644
> > --- a/xen/arch/arm/mm.c
> > +++ b/xen/arch/arm/mm.c
> > @@ -612,6 +612,10 @@ static int xenmem_add_to_physmap_range(struct domain 
> > *d,
> >                                         xatpr->foreign_domid,
> >                                         idx, gpfn);
> >  
> > +        rc = copy_to_guest_offset(xatpr->errs, xatpr->size-1, &rc, 1);
> > +        if ( rc < 0 )
> > +            goto out;
> > +
> >          xatpr->size--;
> >  
> >          /* Check for continuation if it's not the last interation */
> > diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
> > index 3ee2902..62acabd 100644
> > --- a/xen/include/public/memory.h
> > +++ b/xen/include/public/memory.h
> > @@ -236,6 +236,7 @@ DEFINE_XEN_GUEST_HANDLE(xen_add_to_physmap_t);
> >  /* A batched version of add_to_physmap. */
> >  #define XENMEM_add_to_physmap_range 23
> >  struct xen_add_to_physmap_range {
> > +    /* IN */
> >      /* Which domain to change the mapping for. */
> >      domid_t domid;
> >      uint16_t space; /* => enum phys_map_space */
> > @@ -247,8 +248,13 @@ struct xen_add_to_physmap_range {
> >      /* Indexes into space being mapped. */
> >      XEN_GUEST_HANDLE(xen_ulong_t) idxs;
> >  
> > -    /* GPFN in domdwhere the source mapping page should appear. */
> > +    /* GPFN in domid where the source mapping page should appear. */
> >      XEN_GUEST_HANDLE(xen_pfn_t) gpfns;
> > +
> > +    /* OUT */
> > +
> > +    /* Per index error code. */
> > +    XEN_GUEST_HANDLE(int) errs;
> >  };
> >  typedef struct xen_add_to_physmap_range xen_add_to_physmap_range_t;
> >  DEFINE_XEN_GUEST_HANDLE(xen_add_to_physmap_range_t);
> 
> 

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