Re: [Xen-devel] [PATCH 1/4] x86/hyperv: misc cleanup

[Wei Liu <wl@xxxxxxx>]

On Thu, Feb 13, 2020 at 10:46:56AM +0100, Jan Beulich wrote:
> On 12.02.2020 17:09, Wei Liu wrote:
> > --- a/xen/arch/x86/guest/hyperv/private.h
> > +++ b/xen/arch/x86/guest/hyperv/private.h
> > @@ -26,6 +26,6 @@
> >  
> >  DECLARE_PER_CPU(void *, hv_input_page);
> >  DECLARE_PER_CPU(void *, hv_vp_assist);
> > -DECLARE_PER_CPU(unsigned int, hv_vp_index);
> > +DECLARE_PER_CPU(uint32_t, hv_vp_index);
> 
> You've got a co-maintainer ack, i.e. so be it, but FTR this is
> against what CodingStyle says, afaict: "Fixed width types should
> only be used when a fixed width quantity is meant (which for
> example may be a value read from or to be written to a register)."
> If you handed the address (perhaps indirectly, e.g. by converting
> to a physical one first) of this variable to Hyper-V, then things
> would be different. But
> 
>     this_cpu(hv_vp_index) = vp_index_msr;
> 
> would, if unsigned int was wider than 32 bits, not cause any

Did you mean "wouldn't" here?

> issues. And this is the only place the variable currently gets
> accessed, and I expect future uses will just be reads of it (as
> can be seen later in the series).
> 

Yes.

Wei.

> Jan

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