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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

Any Acks/Nacks?

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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