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=-5.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 E628FC2B9F4 for ; Mon, 14 Jun 2021 13:50:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0BCA611CE for ; Mon, 14 Jun 2021 13:50:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234225AbhFNNwM (ORCPT ); Mon, 14 Jun 2021 09:52:12 -0400 Received: from foss.arm.com ([217.140.110.172]:36608 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233803AbhFNNwH (ORCPT ); Mon, 14 Jun 2021 09:52:07 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 294C36D; Mon, 14 Jun 2021 06:50:04 -0700 (PDT) Received: from [10.57.9.136] (unknown [10.57.9.136]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4A2A83F70D; Mon, 14 Jun 2021 06:49:57 -0700 (PDT) Subject: Re: [RFC PATCH V3 08/11] swiotlb: Add bounce buffer remap address setting function To: Christoph Hellwig , Tianyu Lan Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, arnd@arndb.de, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, rppt@kernel.org, hannes@cmpxchg.org, cai@lca.pw, krish.sadhukhan@oracle.com, saravanand@fb.com, Tianyu.Lan@microsoft.com, konrad.wilk@oracle.com, m.szyprowski@samsung.com, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, joro@8bytes.org, will@kernel.org, xen-devel@lists.xenproject.org, davem@davemloft.net, kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, netdev@vger.kernel.org, vkuznets@redhat.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, sunilmut@microsoft.com References: <20210530150628.2063957-1-ltykernel@gmail.com> <20210530150628.2063957-9-ltykernel@gmail.com> <20210607064312.GB24478@lst.de> From: Robin Murphy Message-ID: <94038087-a33c-93c5-27bf-7ec1f6f5f0e3@arm.com> Date: Mon, 14 Jun 2021 14:49:51 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <20210607064312.GB24478@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 2021-06-07 07:43, Christoph Hellwig wrote: > On Sun, May 30, 2021 at 11:06:25AM -0400, Tianyu Lan wrote: >> From: Tianyu Lan >> >> For Hyper-V isolation VM with AMD SEV SNP, the bounce buffer(shared memory) >> needs to be accessed via extra address space(e.g address above bit39). >> Hyper-V code may remap extra address space outside of swiotlb. swiotlb_ >> bounce() needs to use remap virtual address to copy data from/to bounce >> buffer. Add new interface swiotlb_set_bounce_remap() to do that. > > Why can't you use the bus_dma_region ranges to remap to your preferred > address? FWIW, I think a better generalisation for this would be allowing set_memory_decrypted() to return an address rather than implicitly operating in-place, and hide all the various hypervisor hooks behind that. Robin.