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 Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id EC272C433EF for ; Mon, 16 May 2022 07:34:59 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 9A9CF416FA; Mon, 16 May 2022 07:34:59 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id u31TX2f5Nt1R; Mon, 16 May 2022 07:34:58 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 3DE4B40983; Mon, 16 May 2022 07:34:58 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id DCF1EC0039; Mon, 16 May 2022 07:34:57 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 358DFC002D for ; Mon, 16 May 2022 07:34:56 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 1074F81DB2 for ; Mon, 16 May 2022 07:34:56 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp1.osuosl.org (amavisd-new); dkim=pass (2048-bit key) header.d=infradead.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id goasy-TqN7fs for ; Mon, 16 May 2022 07:34:55 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by smtp1.osuosl.org (Postfix) with ESMTPS id 89CBF81DAB for ; Mon, 16 May 2022 07:34:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=w8WGy4XS5eXPvdu5YfW76lcCrip857Hkkv2txNUtWbk=; b=cWV3k/N+6vmcSCEINsuc1SyYS3 BfmjTHk8hKu4jUjnIDxdZHymMOVX+efbSeMcixkrZjvghh6lLqsfQn2nWR+Nb8WWuwn+519/VmTMK IUG1/z574qcIEOO7Efev4KCTIkmUiAMfeni4g71Gb+bS9m+oZgKGYNOqZsAxdkTo3nkIiz32hxQUz 87ixaZ+4IKzE1q16evyHuw0NSokd0xtA76pXi+/hQe2uZj/pz4UCSiG6xFUCDrznojMQ8kyn3Jpib M7EpBmbbtu9OrPW/54vHY2DMtxo4uOoWAd3NQIB3mJL32X3fKzFNA+Fhx206UUIo5/cR6deYR0QJE LVYGJI6g==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nqVFh-006Ubt-57; Mon, 16 May 2022 07:34:49 +0000 Date: Mon, 16 May 2022 00:34:49 -0700 From: Christoph Hellwig To: Tianyu Lan Subject: Re: [RFC PATCH V2 1/2] swiotlb: Add Child IO TLB mem support Message-ID: References: <20220502125436.23607-1-ltykernel@gmail.com> <20220502125436.23607-2-ltykernel@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220502125436.23607-2-ltykernel@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Cc: parri.andrea@gmail.com, michael.h.kelley@microsoft.com, wei.liu@kernel.org, Tianyu Lan , linux-hyperv@vger.kernel.org, konrad.wilk@oracle.com, linux-kernel@vger.kernel.org, hch@infradead.org, iommu@lists.linux-foundation.org, kirill.shutemov@intel.com, thomas.lendacky@amd.com, andi.kleen@intel.com, brijesh.singh@amd.com, vkuznets@redhat.com, kys@microsoft.com, robin.murphy@arm.com, hch@lst.de X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" I don't really understand how 'childs' fit in here. The code also doesn't seem to be usable without patch 2 and a caller of the new functions added in patch 2, so it is rather impossible to review. Also: 1) why is SEV/TDX so different from other cases that need bounce buffering to treat it different and we can't work on a general scalability improvement 2) per previous discussions at how swiotlb itself works, it is clear that another option is to just make pages we DMA to shared with the hypervisor. Why don't we try that at least for larger I/O? _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu