Re: [PATCH 1/3] KVM: X86: Add "nopvspin" parameter to disable PV spinlocks

[Zhenzhong Duan]

On 2019/9/30 23:41, Vitaly Kuznetsov wrote:
> Zhenzhong Duan<zhenzhong.duan@xxxxxxxxxx>  writes:
>
> > There are cases where a guest tries to switch spinlocks to bare metal
> > behavior (e.g. by setting "xen_nopvspin" on XEN platform and
> > "hv_nopvspin" on HYPER_V).
> >
> > That feature is missed on KVM, add a new parameter "nopvspin" to disable
> > PV spinlocks for KVM guest.
> >
> > This new parameter is also intended to replace "xen_nopvspin" and
> > "hv_nopvspin" in the future.
> Any reason to not do it right now? We will probably need to have compat
> code to support xen_nopvspin/hv_nopvspin too but emit a 'is deprecated'
> warning.

Sorry the description isn't clear, I'll fix it.

I did the compat work in the other two patches.
[PATCH 2/3] xen: Mark "xen_nopvspin" parameter obsolete and map it to "nopvspin"
[PATCH 3/3] x86/hyperv: Mark "hv_nopvspin" parameter obsolete and map it to "nopvspin"

> > The global variable pvspin isn't defined as __initdata as it's used at
> > runtime by XEN guest.
> >
> > Refactor the print stuff with pr_* which is preferred.
> Please do it in a separate patch.

Ok, I'll do that in v2. Thanks for review.

Zhenzhong