Re: [Xen-devel] [PATCH 2/4] fix XENMEM_add_to_physmap preemption handling

[Tim Deegan <tim@xxxxxxx>]

At 14:35 +0000 on 18 Dec (1387373707), Jan Beulich wrote:
> Just like for all other hypercalls we shouldn't be modifying the input
> structure - all of the fields are, even if not explicitly documented,
> just inputs.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

> @@ -543,22 +543,32 @@ static long memory_exchange(XEN_GUEST_HA
>  }
>  
>  static int xenmem_add_to_physmap(struct domain *d,
> -                                 struct xen_add_to_physmap *xatp)
> +                                 struct xen_add_to_physmap *xatp,
> +                                 unsigned int start)
>  {
> -    struct xen_add_to_physmap start_xatp;
> -    int rc = 0;
> +    unsigned int done = 0;
> +    long rc = 0;
>  
>      if ( xatp->space != XENMAPSPACE_gmfn_range )
> +    {
> +        ASSERT(!start);

I don't think you've enforced this in the caller; you only check that
the guest hasn't supplied an over-sized start-extent.  I think it's
fine just to ignore start for singleton operations anyway.

Cheers,

Tim.

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