From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH 5/6] xen: arm: add some helpers for
	assessing p2m pte
Date: Tue, 10 Jun 2014 13:29:41 +0100
Message-ID: <1402403381.1250.92.camel@kazak.uk.xensource.com>
References: <1402394127.29980.52.camel@kazak.uk.xensource.com>
	<1402394278-9850-5-git-send-email-ian.campbell@citrix.com>
	<5396EE10.8060804@linaro.org>
	<1402400806.1250.63.camel@kazak.uk.xensource.com>
	<5396F202.4070200@linaro.org>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xen.org>
In-Reply-To: <5396F202.4070200@linaro.org>
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: Julien Grall <julien.grall@linaro.org>
Cc: stefano.stabellini@eu.citrix.com, tim@xen.org, xen-devel@lists.xen.org
List-Id: xen-devel@lists.xenproject.org

On Tue, 2014-06-10 at 12:54 +0100, Julien Grall wrote:
> On 06/10/2014 12:46 PM, Ian Campbell wrote:
> > On Tue, 2014-06-10 at 12:37 +0100, Julien Grall wrote:
> >> On 06/10/2014 10:57 AM, Ian Campbell wrote:
> >>>      mask = SECOND_MASK;
> >>>      second = map_domain_page(pte.p2m.base);
> >>>      pte = second[second_table_offset(paddr)];
> >>> -    if ( !pte.p2m.valid || !pte.p2m.table )
> >>> +    if ( !p2m_table(pte) )
> >>>          goto done;
> >>>  
> >>>      mask = THIRD_MASK;
> >>> @@ -156,11 +161,11 @@ paddr_t p2m_lookup(struct domain *d, paddr_t paddr, p2m_type_t *t)
> >>>      pte = third[third_table_offset(paddr)];
> >>>  
> >>>      /* This bit must be one in the level 3 entry */
> >>> -    if ( !pte.p2m.table )
> >>> +    if ( !p2m_table(pte) )
> >>>          pte.bits = 0;
> >>>  
> >>>  done:
> >>> -    if ( pte.p2m.valid )
> >>> +    if ( p2m_valid(pte) )
> >>
> >> Regardless the current check, I think this should be p2m_entry(pte) to
> >> help code comprehension.
> >>
> >> Indeed, the can only get the address if the pte is pointed to a memory
> >> block.
> > 
> > Yes, but an L3 PTE has the table bit set, which would make
> > p2m_entry(pte) false...
> 
> Hmmm... right. But this bit (ie table bit) doesn't have the same meaning
> on L3. Your comment on p2m_table is confusing.

You mean: /* Remember: L3 entries set the table bit! */ ?

That was intended to be a comment on the two helpers which follow. Do
you have an idea how I could make it clearer? Perhaps appending "So
these two functions will return the opposite to what you expect for L3
ptes"?

> 
> Anyway:
> 
> Acked-by: Julien Grall <julien.grall@linaro.org>
> 

Thanks.