linux-kernel - Re: [Xen-devel] [PATCH v11 08/12] xen/pvh: MMU changes for PVH

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Message-ID: <alpine.DEB.2.02.1312181514510.8667@kaball.uk.xensource.com>
Date:	Wed, 18 Dec 2013 15:15:19 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	<xen-devel@...ts.xenproject.org>, <linux-kernel@...r.kernel.org>,
	<boris.ostrovsky@...cle.com>, <david.vrabel@...rix.com>,
	<mukesh.rathor@...cle.com>, <jbeulich@...e.com>
Subject: Re: [Xen-devel] [PATCH v11 08/12] xen/pvh: MMU changes for PVH

On Wed, 18 Dec 2013, Konrad Rzeszutek Wilk wrote:
> > > @@ -1834,6 +1845,9 @@ static void convert_pfn_mfn(void *v)
> > >  	pte_t *pte = v;
> > >  	int i;
> > >  
> > > +	if (xen_feature(XENFEAT_auto_translated_physmap))
> > > +		return;
> > > +
> > >  	/* All levels are converted the same way, so just treat them
> > >  	   as ptes. */
> > >  	for (i = 0; i < PTRS_PER_PTE; i++)
> > 
> > This is getting pretty bad.
> > Can we find a way to refactor xen_setup_kernel_pagetable so that we
> > don't need all this? Maybe we need a new function?
> 
> Is it that bad? Doing a copy of xen_setup_kernel_pagetable just
> for PVH strikes me as error prone. Having the checks in the
> functions that xen_setup_kernel_pagetable is much easier and
> nicer I think.
> 
> Maybe if we did a big 'if (xen_feature(XEN..)' inside of
> xen_setup_kernel_pagetable that would be easier?

Yes, that should make things clearer.
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