Re: [PATCH v3 04/13] nEPT: Define EPT-specific link_shadow_page()

From: Paolo Bonzini <pbonzini@redhat.com>
To: Jun Nakajima <jun.nakajima@intel.com>
Cc: kvm@vger.kernel.org, Gleb Natapov <gleb@redhat.com>
Subject: Re: [PATCH v3 04/13] nEPT: Define EPT-specific link_shadow_page()
Date: Mon, 20 May 2013 14:43:18 +0200	[thread overview]
Message-ID: <519A1A66.3040209@redhat.com> (raw)
In-Reply-To: <1368939152-11406-4-git-send-email-jun.nakajima@intel.com>

Il 19/05/2013 06:52, Jun Nakajima ha scritto:
> From: Nadav Har'El <nyh@il.ibm.com>
> 
> Since link_shadow_page() is used by a routine in mmu.c, add an
> EPT-specific link_shadow_page() in paging_tmp.h, rather than moving
> it.
> 
> Signed-off-by: Nadav Har'El <nyh@il.ibm.com>
> Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>
> Signed-off-by: Xinhao Xu <xinhao.xu@intel.com>
> ---
>  arch/x86/kvm/paging_tmpl.h | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> index 4c45654..dc495f9 100644
> --- a/arch/x86/kvm/paging_tmpl.h
> +++ b/arch/x86/kvm/paging_tmpl.h
> @@ -461,6 +461,18 @@ static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw,
>  	}
>  }
>  
> +#if PTTYPE == PTTYPE_EPT
> +static void FNAME(link_shadow_page)(u64 *sptep, struct kvm_mmu_page *sp)
> +{
> +	u64 spte;
> +
> +	spte = __pa(sp->spt) | VMX_EPT_READABLE_MASK | VMX_EPT_WRITABLE_MASK |
> +		VMX_EPT_EXECUTABLE_MASK;
> +
> +	mmu_spte_set(sptep, spte);
> +}
> +#endif

The function is small enough that likely the compiler will inline it.
You can just handle it unconditionally with FNAME().

Paolo

>  /*
>   * Fetch a shadow pte for a specific level in the paging hierarchy.
>   * If the guest tries to write a write-protected page, we need to
> @@ -513,7 +525,11 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
>  			goto out_gpte_changed;
>  
>  		if (sp)
> +#if PTTYPE == PTTYPE_EPT
> +			FNAME(link_shadow_page)(it.sptep, sp);
> +#else
>  			link_shadow_page(it.sptep, sp);
> +#endif
>  	}
>  
>  	for (;
> @@ -533,7 +549,11 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
>  
>  		sp = kvm_mmu_get_page(vcpu, direct_gfn, addr, it.level-1,
>  				      true, direct_access, it.sptep);
> +#if PTTYPE == PTTYPE_EPT
> +		FNAME(link_shadow_page)(it.sptep, sp);
> +#else
>  		link_shadow_page(it.sptep, sp);
> +#endif
>  	}
>  
>  	clear_sp_write_flooding_count(it.sptep);
> 