Re: [PATCH v3 3/4] Revert "xen: Introduce 'xen_nopv' to disable PV extensions for HVM guests."

[Zhenzhong Duan]

On 2019/7/2 11:48, Boris Ostrovsky wrote:
> On Mon, Jul 01, 2019 at 10:20:27AM +0800, Zhenzhong Duan wrote:
> > This reverts commit 8d693b911bb9c57009c24cb1772d205b84c7985c.
> >
> > Instead we use an unified parameter 'nopv' for all the hypervisor
> > platforms.
> >
> > Signed-off-by: Zhenzhong Duan<zhenzhong.duan@xxxxxxxxxx>
> > Reviewed-by: Juergen Gross<jgross@xxxxxxxx>
> > Cc: Boris Ostrovsky<boris.ostrovsky@xxxxxxxxxx>
> > Cc: Juergen Gross<jgross@xxxxxxxx>
> > Cc: Stefano Stabellini<sstabellini@xxxxxxxxxx>
> > Cc: Thomas Gleixner<tglx@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar<mingo@xxxxxxxxxx>
> > Cc: Borislav Petkov<bp@xxxxxxxxx>
> > ---
> >   Documentation/admin-guide/kernel-parameters.txt |  4 ----
> >   arch/x86/xen/enlighten_hvm.c                    | 12 +-----------
> >   2 files changed, 1 insertion(+), 15 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 21e08af..d5c3dcc 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -5251,10 +5251,6 @@
> >   			Disables the ticketlock slowpath using Xen PV
> >   			optimizations.
> >   
> > -	xen_nopv	[X86]
> > -			Disables the PV optimizations forcing the HVM guest to
> > -			run as generic HVM guest with no PV drivers.
> > -
> So someone upgrades the kernel and suddenly things work differently?
>
> At least there should be a warning that the option has been replaced
> with 'nopv' (but I would actually keep this option working as well).

OK, I'll add new patch to map xen_nopv to nopv. So if 'xen_nopv' is 
used, we go

to the path for 'nopv'. I will be same effect.

Thanks

Zhenzhong