From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tim Deegan <tim@xen.org>
Subject: Re: [PATCH 11/38] arm: implement p2m lookup
Date: Thu, 7 Jun 2012 10:03:34 +0100
Message-ID: <20120607090334.GC70339@ocelot.phlegethon.org>
References: <1338565113.17466.141.camel@zakaz.uk.xensource.com>
	<1338565207-2888-1-git-send-email-ian.campbell@citrix.com>
	<1338565207-2888-11-git-send-email-ian.campbell@citrix.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
Content-Disposition: inline
In-Reply-To: <1338565207-2888-11-git-send-email-ian.campbell@citrix.com>
List-Unsubscribe: <http://lists.xen.org/cgi-bin/mailman/options/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xen.org>
List-Help: <mailto:xen-devel-request@lists.xen.org?subject=help>
List-Subscribe: <http://lists.xen.org/cgi-bin/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xen.org?subject=subscribe>
Sender: xen-devel-bounces@lists.xen.org
Errors-To: xen-devel-bounces@lists.xen.org
To: Ian Campbell <ian.campbell@citrix.com>
Cc: xen-devel@lists.xen.org
List-Id: xen-devel@lists.xenproject.org

At 15:39 +0000 on 01 Jun (1338565180), Ian Campbell wrote:
> +/*
> + * Lookup the MFN corresponding to a domain's PFN.
> + *
> + * There are no processor functions to do a stage 2 only lookup therefore we
> + * do a a software walk.
> + */
> +paddr_t p2m_lookup(struct domain *d, paddr_t paddr)
> +{
> +    struct p2m_domain *p2m = &d->arch.p2m;
> +    lpae_t pte, *first = NULL, *second = NULL, *third = NULL;
> +    paddr_t maddr = INVALID_PADDR;
> +
> +    spin_lock(&p2m->lock);
> +
> +    first = __map_domain_page(p2m->first_level);
> +    if ( !first[first_table_offset(paddr)].p2m.valid )
> +        goto done_err;
> +    if ( !first[first_table_offset(paddr)].p2m.table )
> +    {
> +        pte = first[first_table_offset(paddr)];
> +        goto done;
> +    }

This would be neater as: 
       pte = first[first_table_offset(paddr)];
       if ( !pte.p2m.valid || !pte.p2m.table )
           goto done;

and test for pte.valid at 'done'.

It would be nice to do the three levels in a loop as well, but the weird
way the table bit behaves in third-level entries might make that more
confusing than the straight-line version.

Tim.