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

[Keir Fraser <keir@xen.org>]

Acked-by: Keir Fraser <keir@xen.org>

On 16/01/2013 14:39, "Stefano Stabellini" <Stefano.Stabellini@eu.citrix.com>
wrote:

> Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> 
> On Wed, 16 Jan 2013, Ian Campbell wrote:
>> 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@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);
>> 
>> 
>>