Re: [Xen-devel] [PATCH for-next RFC 6/8] x86: make probe_xen return boolean value

[Wei Liu <wl@xxxxxxx>]

On Wed, Sep 25, 2019 at 12:44:27PM +0200, Roger Pau Monné wrote:
> On Mon, Sep 23, 2019 at 11:09:29AM +0100, Wei Liu wrote:
> > We need indication whether it has succeeded or not.
> > 
> > Signed-off-by: Wei Liu <liuwe@xxxxxxxxxxxxx>
> 
> The code LGTM, I have just a suggestion on the approach.
> 
> > ---
> >  xen/arch/x86/guest/hypervisor.c | 5 ++++-
> >  xen/arch/x86/guest/xen/xen.c    | 7 ++++---
> >  xen/include/asm-x86/guest/xen.h | 4 ++--
> >  3 files changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/xen/arch/x86/guest/hypervisor.c 
> > b/xen/arch/x86/guest/hypervisor.c
> > index b0a724bf13..fb572b0402 100644
> > --- a/xen/arch/x86/guest/hypervisor.c
> > +++ b/xen/arch/x86/guest/hypervisor.c
> > @@ -34,7 +34,10 @@ void __init probe_hypervisor(void)
> >      if ( !(cpuid_ecx(1) & cpufeat_mask(X86_FEATURE_HYPERVISOR)) )
> >          return;
> >  
> > -    probe_xen();
> > +    if ( probe_xen() )
> > +        return;
> > +
> > +    /* Hyper-V probing to follow. */
> 
> Instead of having to append a new probe_foo here every time support for
> running on a new hypervisor is added, you could do something similar
> to what's done in REGISTER_VPCI_INIT, where each hypervisor would
> register it's own set of helpers and probe function in a specific
> section, and then you would just iterate over all the guest support
> that's compiled in Xen.
> 
> That would also prevent you from having to export a dummy probe_xen
> helper if CONFIG_XEN_GUEST is not defined.
> 
> Anyway, maybe that's overkill...

Let's see what Andrew and Jan think.

Either works for me -- it is just a matter of writing code, but
obviously the less work the better. :-)

Wei.

> 
> Thanks, Roger.

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