From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by smtp.lore.kernel.org (Postfix) with ESMTPS id A4313C43217
	for <linuxppc-dev@archiver.kernel.org>; Tue, 12 Apr 2022 06:21:55 +0000 (UTC)
Received: from boromir.ozlabs.org (localhost [IPv6:::1])
	by lists.ozlabs.org (Postfix) with ESMTP id 4Kcwc170Qdz3bcQ
	for <linuxppc-dev@archiver.kernel.org>; Tue, 12 Apr 2022 16:21:53 +1000 (AEST)
Authentication-Results: lists.ozlabs.org;
 spf=none (no SPF record) smtp.mailfrom=lst.de
 (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de;
 receiver=<UNKNOWN>)
Received: from verein.lst.de (verein.lst.de [213.95.11.211])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by lists.ozlabs.org (Postfix) with ESMTPS id 4KcwbZ35h4z2xSM
 for <linuxppc-dev@lists.ozlabs.org>; Tue, 12 Apr 2022 16:21:28 +1000 (AEST)
Received: by verein.lst.de (Postfix, from userid 2407)
 id CD9FC68AA6; Tue, 12 Apr 2022 08:21:20 +0200 (CEST)
Date: Tue, 12 Apr 2022 08:21:20 +0200
From: Christoph Hellwig <hch@lst.de>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH 10/15] swiotlb: add a SWIOTLB_ANY flag to lift the low
 memory restriction
Message-ID: <20220412062120.GA7796@lst.de>
References: <20220404050559.132378-1-hch@lst.de>
 <20220404050559.132378-11-hch@lst.de> <Yk4vfAd0J5u+wUsq@char.us.oracle.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Yk4vfAd0J5u+wUsq@char.us.oracle.com>
User-Agent: Mutt/1.5.17 (2007-11-01)
X-BeenThere: linuxppc-dev@lists.ozlabs.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>
Cc: linux-hyperv@vger.kernel.org, linux-ia64@vger.kernel.org,
 linux-pci@vger.kernel.org, linux-riscv@lists.infradead.org,
 Christoph Hellwig <hch@lst.de>, linux-s390@vger.kernel.org,
 Stefano Stabellini <sstabellini@kernel.org>, Joerg Roedel <joro@8bytes.org>,
 x86@kernel.org, tboot-devel@lists.sourceforge.net,
 xen-devel@lists.xenproject.org, David Woodhouse <dwmw2@infradead.org>,
 Tom Lendacky <thomas.lendacky@amd.com>,
 Anshuman Khandual <anshuman.khandual@arm.com>,
 Boris Ostrovsky <boris.ostrovsky@oracle.com>,
 linux-arm-kernel@lists.infradead.org, Juergen Gross <jgross@suse.com>,
 linuxppc-dev@lists.ozlabs.org, linux-mips@vger.kernel.org,
 iommu@lists.linux-foundation.org, Robin Murphy <robin.murphy@arm.com>,
 Lu Baolu <baolu.lu@linux.intel.com>
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

On Wed, Apr 06, 2022 at 08:25:32PM -0400, Konrad Rzeszutek Wilk wrote:
> > diff --git a/arch/powerpc/platforms/pseries/svm.c b/arch/powerpc/platforms/pseries/svm.c
> > index c5228f4969eb2..3b4045d508ec8 100644
> > --- a/arch/powerpc/platforms/pseries/svm.c
> > +++ b/arch/powerpc/platforms/pseries/svm.c
> > @@ -28,7 +28,7 @@ static int __init init_svm(void)
> >  	 * need to use the SWIOTLB buffer for DMA even if dma_capable() says
> >  	 * otherwise.
> >  	 */
> > -	swiotlb_force = SWIOTLB_FORCE;
> > +	ppc_swiotlb_flags |= SWIOTLB_ANY | SWIOTLB_FORCE;
> 
> This is the only place you set the ppc_swiotlb_flags.. so I wonder why
> the '|=' instead of just '=' ?

Preparing for setting others and not clobbering the value.