Re: [Xen-devel] [PATCH] xen: don't use privcmd_call() from xen_mc_flush()

[Jan Beulich]

>>> On 13.06.18 at 12:05, <JBeulich@xxxxxxxx> wrote:
>>>> On 13.06.18 at 11:58, <jgross@xxxxxxxx> wrote:
>> Using privcmd_call() for a singleton multicall seems to be wrong, as
>> privcmd_call() is using stac()/clac() to enable hypervisor access to
>> Linux user space.
>> 
>> Add a new xen_single_call() function to be use for that purpose.
>> 
>> Reported-by: Jan Beulich <jbeulich@xxxxxxxx>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> 
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Actually I've only now realized that this isn't a real problem right now:
PV can't use SMAP (we don't provide a virtualized version of it), and
HVM/PVH can't use multicalls (which may have to change for PVH Dom0,
so having the change in place is helpful anyway), so the whole
in-kernel logic to collect and issue batches should be unreachable there.

But perhaps the commit message would benefit from a little bit of
re-wording.

Jan