Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2F752C4167B for ; Tue, 14 Dec 2021 19:03:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237307AbhLNTDj (ORCPT ); Tue, 14 Dec 2021 14:03:39 -0500 Received: from mga09.intel.com ([134.134.136.24]:10765 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234429AbhLNTDh (ORCPT ); Tue, 14 Dec 2021 14:03:37 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1639508617; x=1671044617; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=moCcawZ7TdWbgzj24jFWevKSGpg/rJ0aDgg6BUfDmHk=; b=hw4E+UXeMyJUwSRQ+YIF1aIptpEZnRd55zIL939soR6YeZ9zqmmYHHfQ ThoaYxGbz7g+Vur8t/dswj2VDPkaolFOKqjGBv5HysJ5a/E/ioyTuwpwq eh1WvFtlDKv+xHXU7v+Qz22lZp34YA0IV3r5atGJoW82mUzfKMIL+MJGT BrZNqOFBtvDr0we1M21cZMrM5Ct/V1lWZD3FIHI2t94xfxS3xSoYeV0tS zeLlCAOZjnsQ9RHSNvP7Du6w7FMt3AZEji8FClmHB8thM4NinHI15iZxB qmH5v+qMrvjrKIRDvwLEJJjAoIQdKDvQNv565lCaerfLDQS3V2omgs0eh A==; X-IronPort-AV: E=McAfee;i="6200,9189,10197"; a="238870440" X-IronPort-AV: E=Sophos;i="5.88,205,1635231600"; d="scan'208";a="238870440" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2021 10:40:52 -0800 X-IronPort-AV: E=Sophos;i="5.88,205,1635231600"; d="scan'208";a="505470613" Received: from soniasah-mobl2.amr.corp.intel.com (HELO [10.212.242.116]) ([10.212.242.116]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Dec 2021 10:40:51 -0800 Subject: Re: [PATCH V7 1/5] swiotlb: Add swiotlb bounce buffer remap function for HV IVM To: Tianyu Lan , 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, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, davem@davemloft.net, kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, arnd@arndb.de, hch@infradead.org, m.szyprowski@samsung.com, robin.murphy@arm.com, thomas.lendacky@amd.com, Tianyu.Lan@microsoft.com, michael.h.kelley@microsoft.com Cc: 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, brijesh.singh@amd.com, konrad.wilk@oracle.com, hch@lst.de, joro@8bytes.org, parri.andrea@gmail.com References: <20211213071407.314309-1-ltykernel@gmail.com> <20211213071407.314309-2-ltykernel@gmail.com> <198e9243-abca-b23e-0e8e-8581a7329ede@intel.com> <3243ff22-f6c8-b7cd-26b7-6e917e274a7c@gmail.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <3243ff22-f6c8-b7cd-26b7-6e917e274a7c@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/21 8:36 PM, Tianyu Lan wrote: > On 12/14/2021 12:45 AM, Dave Hansen wrote: >> On 12/12/21 11:14 PM, Tianyu Lan wrote: >>> In Isolation VM with AMD SEV, bounce buffer needs to be accessed via >>> extra address space which is above shared_gpa_boundary (E.G 39 bit >>> address line) reported by Hyper-V CPUID ISOLATION_CONFIG. The access >>> physical address will be original physical address + >>> shared_gpa_boundary. >>> The shared_gpa_boundary in the AMD SEV SNP spec is called virtual top of >>> memory(vTOM). Memory addresses below vTOM are automatically treated as >>> private while memory above vTOM is treated as shared. >> >> This seems to be independently reintroducing some of the SEV >> infrastructure.  Is it really OK that this doesn't interact at all with >> any existing SEV code? >> >> For instance, do we need a new 'swiotlb_unencrypted_base', or should >> this just be using sme_me_mask somehow? > >        Thanks for your review. Hyper-V provides a para-virtualized > confidential computing solution based on the AMD SEV function and not > expose sev&sme capabilities to guest. So sme_me_mask is unset in the > Hyper-V Isolation VM. swiotlb_unencrypted_base is more general solution > to handle such case of different address space for encrypted and > decrypted memory and other platform also may reuse it. I don't really understand how this can be more general any *not* get utilized by the existing SEV support.