From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 051FDC83000 for ; Tue, 28 Apr 2020 22:53:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C52F52070B for ; Tue, 28 Apr 2020 22:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588114437; bh=ywVtSYZTVnlMl6doGY8VJNhfjwkHTSTfeN9miNjuHLc=; h=Date:From:To:cc:Subject:In-Reply-To:References:List-ID:From; b=t1xntNC6ATNh873ihjZbVyrPYU69dGil78w3Uqv/VywJ2s34hd19FefFh3mSw2vIL Zt4+I35dlh0ZTtfYxKWLKdVVyX6n5R7A6wpMDktzXaUwH9zya1r4f66GkfSL11ghdx YDGfqSru1UB1oXDIO5XRlwMAfUC3PUqnhnxGuWeU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726559AbgD1Wx4 (ORCPT ); Tue, 28 Apr 2020 18:53:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:40740 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726042AbgD1Wx4 (ORCPT ); Tue, 28 Apr 2020 18:53:56 -0400 Received: from localhost (c-67-164-102-47.hsd1.ca.comcast.net [67.164.102.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id ACB2E206D9; Tue, 28 Apr 2020 22:53:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588114436; bh=ywVtSYZTVnlMl6doGY8VJNhfjwkHTSTfeN9miNjuHLc=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=K8ywBOYNFWIro+8tTcJPkzDdktI4MKmTQFI2jKuDDCZxz/UPDSdJCkEwANhDBlV4Z +AD2jXT3SglB96bLRp2T+E2dhPpvIycmfgpopwde4gOSyMWOMgY/EG/59z2V1xC782 pzdsNh2DvdLoOlNaBrJ/mPX3Dl7yMXVfFt5esrDw= Date: Tue, 28 Apr 2020 15:53:55 -0700 (PDT) From: Stefano Stabellini X-X-Sender: sstabellini@sstabellini-ThinkPad-T480s To: Srivatsa Vaddagiri cc: konrad.wilk@oracle.com, mst@redhat.com, jasowang@redhat.com, jan.kiszka@siemens.com, will@kernel.org, stefano.stabellini@xilinx.com, iommu@lists.linux-foundation.org, virtualization@lists.linux-foundation.org, virtio-dev@lists.oasis-open.org, tsoni@codeaurora.org, pratikp@codeaurora.org, christoffer.dall@arm.com, alex.bennee@linaro.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/5] virtio: Add bounce DMA ops In-Reply-To: <1588073958-1793-6-git-send-email-vatsa@codeaurora.org> Message-ID: References: <1588073958-1793-1-git-send-email-vatsa@codeaurora.org> <1588073958-1793-6-git-send-email-vatsa@codeaurora.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 28 Apr 2020, Srivatsa Vaddagiri wrote: > For better security, its desirable that a guest VM's memory is > not accessible to any entity that executes outside the context of > guest VM. In case of virtio, backend drivers execute outside the > context of guest VM and in general will need access to complete > guest VM memory. One option to restrict the access provided to > backend driver is to make use of a bounce buffer. The bounce > buffer is accessible to both backend and frontend drivers. All IO > buffers that are in private space of guest VM are bounced to be > accessible to backend. [...] > +static int __init virtio_bounce_setup(struct reserved_mem *rmem) > +{ > + unsigned long node = rmem->fdt_node; > + > + if (!of_get_flat_dt_prop(node, "no-map", NULL)) > + return -EINVAL; > + > + return virtio_register_bounce_buffer(rmem->base, rmem->size); > +} > + > +RESERVEDMEM_OF_DECLARE(virtio, "virtio_bounce_pool", virtio_bounce_setup); Is this special reserved-memory region documented somewhere?