Re: [Xen-devel] [PATCH 4/4] x86/PoD: Command line option to prohibit any PoD operations

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.11.15 at 15:32, <ian.campbell@xxxxxxxxxx> wrote:
> On Mon, 2015-11-02 at 06:53 -0700, Jan Beulich wrote:
>> > > > On 30.10.15 at 19:33, <andrew.cooper3@xxxxxxxxxx> wrote:
>> > --- a/xen/common/memory.c
>> > +++ b/xen/common/memory.c
>> > @@ -818,6 +818,10 @@ long do_memory_op(unsigned long cmd,
>> > XEN_GUEST_HANDLE_PARAM(void) arg)
>> >          if ( unlikely(start_extent >= reservation.nr_extents) )
>> >              return start_extent;
>> >  
>> > +        if ( unlikely(!opt_pod_enabled) &&
>> > +             (reservation.mem_flags & XENMEMF_populate_on_demand) )
>> > +            return start_extent;
>> 
>> A few lines down we can see that XENMEMF_populate_on_demand
>> gets honored only for XENMEM_populate_physmap. Perhaps you
>> shouldn't fail the other two which ignore the flag anyway?
> 
> Setting an unexpected flag surely ought to be an error? Admittedly that
> particular ship may have sailed WRT this public ABI.

Without that latter aspect I would certainly answer the question
with "Yes".

Jan


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