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

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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.

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