Re: [Xen-devel] [PATCH v2 12/23] x86: monitor.o is currently HVM only

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Wed, Aug 29, 2018 at 10:42 AM Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
>
> On Mon, Aug 27, 2018 at 09:18:29AM -0600, Jan Beulich wrote:
> > >>> On 26.08.18 at 14:19, <wei.liu2@xxxxxxxxxx> wrote:
> > > There has been plan to make PV work, but it is not yet there.  Provide
> > > stubs to make it build with !CONFIG_HVM.
> > >
> > > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> > > ---
> > >  xen/arch/x86/Makefile         |  2 +-
> > >  xen/include/asm-x86/monitor.h | 14 ++++++++++++++
> > >  2 files changed, 15 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
> > > index 9b9b63a..43f9189 100644
> > > --- a/xen/arch/x86/Makefile
> > > +++ b/xen/arch/x86/Makefile
> > > @@ -45,7 +45,7 @@ obj-y += microcode_amd.o
> > >  obj-y += microcode_intel.o
> > >  obj-y += microcode.o
> > >  obj-y += mm.o x86_64/mm.o
> > > -obj-y += monitor.o
> > > +obj-$(CONFIG_HVM) += monitor.o
> > >  obj-y += mpparse.o
> > >  obj-y += nmi.o
> > >  obj-y += numa.o
> > > diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
> > > index 4988903..09f7f8a 100644
> > > --- a/xen/include/asm-x86/monitor.h
> > > +++ b/xen/include/asm-x86/monitor.h
> > > @@ -99,10 +99,24 @@ static inline uint32_t
> > > arch_monitor_get_capabilities(struct domain *d)
> > >  int arch_monitor_domctl_event(struct domain *d,
> > >                                struct xen_domctl_monitor_op *mop);
> > >
> > > +#ifdef CONFIG_HVM
> > > +
> > >  int arch_monitor_init_domain(struct domain *d);
> > >
> > >  void arch_monitor_cleanup_domain(struct domain *d);
> > >
> > > +#else
> > > +
> > > +static inline int arch_monitor_init_domain(struct domain *d)
> > > +{
> > > +    return 0;
> > > +}
> > > +
> > > +static inline void arch_monitor_cleanup_domain(struct domain *d)
> > > +{}
> > > +
> > > +#endif
> >
> > Wouldn't the entire XEN_DOMCTL_VM_EVENT_OP_MONITOR case
> > in vm_event_domctl() then better be put in an #ifdef instead?
>
> I didn't do that because that was common to both ARM and x86.
>
> But now looking at the ARM counterpart, it is not supported either. When
> it is eventually supported on ARM, it will be likely to be dependent on
> CONFIG_HVM anyway. So I think I can put XEN_DOMCTL_VM_EVENT_OP_MONITOR
> under CONFIG_HVM.
>

It is not that it is not supported, it is that it's not (yet) needed.
I think it would be better to have ifdef CONFIG_HVM only in code
that's reached on x86 and not common ones.

Tamas

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