Re: [Xen-devel] [PATCH v1 2/8]: PVH mmu changes

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2012-09-24 at 15:04 +0100, Stefano Stabellini wrote:
> On Fri, 21 Sep 2012, Mukesh Rathor wrote:
> > +struct pvh_remap_data {
> > +   unsigned long fgmfn;            /* foreign domain's gmfn */
> > +   pgprot_t prot;
> > +   domid_t  domid;
> > +   struct xen_pvh_pfn_info *pvhinfop;
> > +};
> > +
> > +static int pvh_map_pte_fn(pte_t *ptep, pgtable_t token, unsigned long 
> > addr, 
> > +                   void *data)
> > +{
> > +   int rc;
> > +   struct pvh_remap_data *remapp = data;
> > +   struct xen_pvh_pfn_info *pvhp = remapp->pvhinfop;
> > +   unsigned long pfn = page_to_pfn(pvhp->pi_paga[pvhp->pi_next_todo++]);
> > +   pte_t pteval = pte_mkspecial(pfn_pte(pfn, remapp->prot));
> > +
> > +   if ((rc=pvh_add_to_xen_p2m(pfn, remapp->fgmfn, remapp->domid)))
> > +           return rc;
> > +   native_set_pte(ptep, pteval);
> > +
> > +   return 0;
> > +}
> > +
> > +/* The only caller at moment passes one gmfn at a time.
> > + * PVH TBD/FIXME: expand this in future to honor batch requests.
> > + */
> > +static int pvh_remap_gmfn_range(struct vm_area_struct *vma,
> > +                           unsigned long addr, unsigned long mfn, int nr,
> > +                           pgprot_t prot, unsigned domid,
> > +                           struct xen_pvh_pfn_info *pvhp)
> > +{
> > +   int err;
> > +   struct pvh_remap_data pvhdata;
> > +
> > +   if (nr > 1)
> > +           return -EINVAL;
> > +
> > +   pvhdata.fgmfn = mfn;
> > +   pvhdata.prot = prot;
> > +   pvhdata.domid = domid;
> > +   pvhdata.pvhinfop = pvhp;
> > +   err = apply_to_page_range(vma->vm_mm, addr, nr << PAGE_SHIFT,
> > +                             pvh_map_pte_fn, &pvhdata);
> > +   flush_tlb_all();
> > +   return err;
> > +}
> > +
> >  #define REMAP_BATCH_SIZE 16
> >  
> >  struct remap_data {
> > @@ -2329,7 +2468,9 @@ static int remap_area_mfn_pte_fn(pte_t *ptep, 
> > pgtable_t token,
> >  int xen_remap_domain_mfn_range(struct vm_area_struct *vma,
> >                            unsigned long addr,
> >                            unsigned long mfn, int nr,
> > -                          pgprot_t prot, unsigned domid)
> > +                          pgprot_t prot, unsigned domid,
> > +                          struct xen_pvh_pfn_info *pvhp)
> > +
> 
> xen_remap_domain_mfn_range is a cross-architecture call (it is available
> on ARM as well). We cannot leak architecture specific informations like
> xen_pvh_pfn_info in the parameter list.
> It seems to be that xen_pvh_pfn_info contains arch-agnostic information:
> in that case you just need to rename the struct to something more
> generic. Otherwise if it really contains x86 specific info, you can
> change it into an opaque pointer.

... or explode it into the relevant constituents struct members which
need to be passed over the interface when calling these functions.

Ian.


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