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

[Mats Petersson <mats.petersson@citrix.com>]

On 16/01/13 14:28, Ian Campbell wrote:
> Any Acks/Nacks?
>
> This touches both ARM and x86 (although x86 only notionally until the
> PVH stuff is merged).
Acked-by: Mats Petersson <mats.petersson@citrix.com>
>
> 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@citrix.com>
>> Cc: Mats Petersson <mats.petersson@citrix.com>
>> Cc: Mukesh Rathor <mukesh.rathor@oracle.com>
>> Cc: Jan Beulich <JBeulich@suse.com>
>> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>> Cc: tim@xen.org
>> Cc: stefano.stabellini@citrix.com
>> Cc: keir@xen.org
>> ---
>>   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);
>