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[209.85.160.181]) by smtp.gmail.com with ESMTPSA id f5sm807312qto.67.2021.01.11.23.47.51 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Jan 2021 23:47:52 -0800 (PST) Received: by mail-qt1-f181.google.com with SMTP id j26so1013711qtq.8 for ; Mon, 11 Jan 2021 23:47:51 -0800 (PST) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 0a494c3c-b5dd-4948-8f12-72d22f174c01 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=j7gLFMlxBCQENVWtNxS2npLHFlF1Oh0HPmJ2b4uXz4E=; b=Muj3J6AUcKeWXk2QVKpBxfCJmD1ZNU3ECoTrLMhnZ3l10BcmT1KWV3KJZVJiyjnmgp tXnYNLGybukalejR/JL4Ccq0hthA+yksiWl3Xj9n38DlJXhcHL4x7k7Hi60j74u9oC5X xVXg0JvakYs/Mgnk3DB5tWgDJ2Wm5qz5NT8oI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=j7gLFMlxBCQENVWtNxS2npLHFlF1Oh0HPmJ2b4uXz4E=; b=Oa3apcbV4wI0tAteR7VEip+i9Zzp0LL1r/WbgLTnSpkwsB4iaUe3IXnC2ggtWWvCL+ juolOOVk0O3NSOI+r8n6DDyMdsFb3Ifz/BAJMDwwE6JaJJr2jSSoQn403QHN3QUMFyHk YYL15yL+myslJ7kMay7UmoUDRtMcmykWK2UycXS003XX1ims9QmZMTSiODz5jLTrVLhr 7NFdJKzj4hIWQPk7bWEwKlzCjuevAy+T++eam41jVqFL1kQtBToUsxyv4Es/v+xbG6QB 0bkkPOiKlXqf8tn64FBCquoWgyYwsOEh+Lv/gCUTBZX1x82d5HhMpf91zxOOQwzU4aRG urow== X-Gm-Message-State: AOAM531v/9JHE3RZQmLucQOuAJVyVvfn+WLgMp22jt7QdZRSN+O2Eusj 2DEMgAC/FbbSKlG+lbQ9dSN3VD+u/URqKg== X-Google-Smtp-Source: ABdhPJzYBBUNiHzy/KAKPt3FBBXb8dzo48raxZMt12xAAHNxtCZeyLYwC4fg0m4z/eCZ8wn01L1a9w== X-Received: by 2002:a05:620a:14a:: with SMTP id e10mr3090958qkn.103.1610437672704; Mon, 11 Jan 2021 23:47:52 -0800 (PST) X-Received: by 2002:a05:6638:c52:: with SMTP id g18mr3073726jal.84.1610437670186; Mon, 11 Jan 2021 23:47:50 -0800 (PST) MIME-Version: 1.0 References: <20210106034124.30560-1-tientzu@chromium.org> <20210106034124.30560-6-tientzu@chromium.org> <20210106185757.GB109735@localhost.localdomain> <20210107180032.GB16519@char.us.oracle.com> <4cce7692-7184-9b25-70f2-b821065f3b25@gmail.com> In-Reply-To: <4cce7692-7184-9b25-70f2-b821065f3b25@gmail.com> From: Claire Chang Date: Tue, 12 Jan 2021 15:47:39 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH v3 5/6] dt-bindings: of: Add restricted DMA pool To: Florian Fainelli Cc: Konrad Rzeszutek Wilk , Rob Herring , mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, "list@263.net:IOMMU DRIVERS" , Joerg Roedel , will@kernel.org, Frank Rowand , boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, Christoph Hellwig , Marek Szyprowski , Robin Murphy , grant.likely@arm.com, xypron.glpk@gmx.de, Thierry Reding , mingo@kernel.org, bauerman@linux.ibm.com, peterz@infradead.org, Greg KH , Saravana Kannan , rafael.j.wysocki@intel.com, heikki.krogerus@linux.intel.com, Andy Shevchenko , rdunlap@infradead.org, dan.j.williams@intel.com, Bartosz Golaszewski , linux-devicetree , lkml , linuxppc-dev@lists.ozlabs.org, xen-devel@lists.xenproject.org, Tomasz Figa , Nicolas Boichat Content-Type: text/plain; charset="UTF-8" On Fri, Jan 8, 2021 at 2:15 AM Florian Fainelli wrote: > > On 1/7/21 10:00 AM, Konrad Rzeszutek Wilk wrote: > >>> > >>> > >>> - Nothing stops the physical device from bypassing the SWIOTLB buffer. > >>> That is if an errant device screwed up the length or DMA address, the > >>> SWIOTLB would gladly do what the device told it do? > >> > >> So the system needs to provide a way to lock down the memory access, e.g. MPU. > > > > OK! Would it be prudent to have this in the description above perhaps? > > Yes this is something that must be documented as a requirement for the > restricted DMA pool users, otherwise attempting to do restricted DMA > pool is no different than say, using a device private CMA region. > Without the enforcement, this is just a best effort. Will add in the next version. > -- > Florian