Re: [Xen-devel] [PATCH v5 4/5] x86/mm: put HVM only code under CONFIG_HVM

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Sep 24, 2018 at 04:58:23PM +0100, George Dunlap wrote:
> On 09/21/2018 04:54 PM, Wei Liu wrote:
> > Going through the code, HAP, EPT, PoD and ALTP2M depend on HVM code.
> > Put these components under CONFIG_HVM. This further requires putting
> > one of the vm event under CONFIG_HVM.
> > 
> > Altp2m requires a bit more attention because its code is embedded in
> > generic x86 p2m code.
> > 
> > Also make hap_enabled evaluate to false when !CONFIG_HVM. Make sure it
> > evaluate its parameter to avoid unused variable warnings in its users.
> > 
> > Also sort items in Makefile while at it.
> > 
> > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> > Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
> > Acked-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> 
> One comment...
> 
> > diff --git a/xen/include/asm-x86/altp2m.h b/xen/include/asm-x86/altp2m.h
> > index 64c7618..41fdd82 100644
> > --- a/xen/include/asm-x86/altp2m.h
> > +++ b/xen/include/asm-x86/altp2m.h
> > @@ -18,12 +18,14 @@
> >  #ifndef __ASM_X86_ALTP2M_H
> >  #define __ASM_X86_ALTP2M_H
> >  
> > +#ifdef CONFIG_HVM
> > +
> >  #include <xen/types.h>
> >  #include <xen/sched.h>         /* for struct vcpu, struct domain */
> >  #include <asm/hvm/vcpu.h>      /* for vcpu_altp2m */
> >  
> >  /* Alternate p2m HVM on/off per domain */
> > -static inline bool_t altp2m_active(const struct domain *d)
> > +static inline bool altp2m_active(const struct domain *d)
> >  {
> >      return d->arch.altp2m_active;
> >  }
> > @@ -37,5 +39,14 @@ static inline uint16_t altp2m_vcpu_idx(const struct vcpu 
> > *v)
> >  {
> >      return vcpu_altp2m(v).p2midx;
> >  }
> > +#else
> > +
> > +static inline bool altp2m_active(const struct domain *d)
> > +{
> > +    return false;
> > +}
> > +
> > +uint16_t altp2m_vcpu_idx(const struct vcpu *v);
> 
> Hmm, this looks like another, "I assume calls to this function will be
> optimized out in the !CONFIG_HVM case"?

Yes.

> 
> I'd appreciate at least a comment when you do that sort of thing. :-)

Will do.

> 
> With a comment added:
> 
> Reviewed-by: George Dunlap <george.dunlap@xxxxxxxxxx>

Thanks.

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