Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 8 Sep 2020 06:36:19 +0100
From:   Christoph Hellwig <hch@infradead.org>
To:     Tom Murphy <murphyt7@tcd.ie>
Cc:     Christoph Hellwig <hch@infradead.org>,
        iommu@lists.linux-foundation.org,
        David Woodhouse <dwmw2@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH V2 5/5] DO NOT MERGE: iommu: disable list appending in
 dma-iommu
Message-ID: <20200908053619.GA15418@infradead.org>
References: <20200903201839.7327-1-murphyt7@tcd.ie>
 <20200903201839.7327-6-murphyt7@tcd.ie>
 <20200907070035.GA25114@infradead.org>
 <CALQxJute8_y=JsW4UV1awSccOjxT_1OyPdymq=R_PurVQzENeQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CALQxJute8_y=JsW4UV1awSccOjxT_1OyPdymq=R_PurVQzENeQ@mail.gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Sep 07, 2020 at 09:18:50PM +0100, Tom Murphy wrote:
> Yeah we talked about passing an attr to map_sg to disable merging at
> the following microconfernce:
> https://linuxplumbersconf.org/event/7/contributions/846/
> As far as I can remember everyone seemed happy with that solution. I
> won't be working on this though as I don't have any more time to
> dedicate to this. It seems Lu Baolu will take over this.

I'm absolutely again passing a flag.  Tha just invites further
abuse.  We need a PCI ID based quirk or something else that can't
be as easily abused.