Re: [Xen-devel] [PATCH RFC v1 62/74] xen/pvshim: memory hotplug

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.01.18 at 14:36, <roger.pau@xxxxxxxxxx> wrote:
> On Tue, Jan 09, 2018 at 03:42:01AM -0700, Jan Beulich wrote:
>> >>> On 04.01.18 at 14:06, <wei.liu2@xxxxxxxxxx> wrote:
>> > @@ -1015,6 +1024,11 @@ long do_memory_op(unsigned long cmd, 
>> > XEN_GUEST_HANDLE_PARAM(void) arg)
>> >                  __HYPERVISOR_memory_op, "lh",
>> >                  op | (rc << MEMOP_EXTENT_SHIFT), arg);
>> >  
>> > +#ifdef CONFIG_X86
>> > +        if ( pv_shim && op == XENMEM_decrease_reservation )
>> > +            pv_shim_offline_memory(args.nr_extents, args.extent_order);
>> > +#endif
>> 
>> Looking at both of these changes - is it somewhere being made
>> sure that shim containers won't boot in PoD mode?
>> 
>> For the latter change - is this correct when the operation has been
>> preempted? I think you want to offline only the delta between
>> start and args.nr_done.
> 
> AFAICT this function will only be called once, even when preempted.
> On the online case it's only called when args.nr_done == 0, and in the
> offline case it's only called after the work has been completely done.

No, and that's the point of my earlier comment: You call the function
solely based on the value of op, not considering at all whether you
were preempted. Or am I overlooking anything?

Jan


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