From mboxrd@z Thu Jan  1 00:00:00 1970
From: Will Deacon <will.deacon@arm.com>
Subject: Re: [PATCH v3 08/32] arm64: KVM: architecture specific MMU backend
Date: Wed, 24 Apr 2013 12:10:02 +0100
Message-ID: <20130424111002.GJ21850@mudshark.cambridge.arm.com>
References: <1365437854-30214-1-git-send-email-marc.zyngier@arm.com>
 <1365437854-30214-9-git-send-email-marc.zyngier@arm.com>
 <20130423225816.GC20569@gmail.com>
 <5177BBEE.1090209@arm.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Christoffer Dall <cdall@cs.columbia.edu>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Christopher Covington <cov@codeaurora.org>
To: Marc Zyngier <Marc.Zyngier@arm.com>
Return-path: <kvm-owner@vger.kernel.org>
Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:39489 "EHLO
	cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1753990Ab3DXLKZ (ORCPT
	<rfc822;kvm@vger.kernel.org>); Wed, 24 Apr 2013 07:10:25 -0400
Content-Disposition: inline
In-Reply-To: <5177BBEE.1090209@arm.com>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On Wed, Apr 24, 2013 at 12:03:10PM +0100, Marc Zyngier wrote:
> On 23/04/13 23:58, Christoffer Dall wrote:
> > I noticed that this doesn't do any cache cleaning.  Are the MMU page
> > table walks guaranteed to be coherent with the MMU on arm64?
> 
> I suppose you meant the cache. In this case, yes. The hardware page
> table walker must snoop the caches.

Also, for ARMv7, SMP implies that the hardware walker snoops the cache. I
recently upstreamed some patches for this (see "ARM: 7691/1: mm: kill unused
TLB_CAN_READ_FROM_L1_CACHE and use ALT_SMP instead" in -next), so you might
want to check if there are any remaining, redundant flushes in kvm for ARMv7.

Will