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,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 04AB2C433ED for ; Fri, 23 Apr 2021 15:14:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CE5D2611C1 for ; Fri, 23 Apr 2021 15:14:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231221AbhDWPO6 (ORCPT ); Fri, 23 Apr 2021 11:14:58 -0400 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:59963 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230470AbhDWPO5 (ORCPT ); Fri, 23 Apr 2021 11:14:57 -0400 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.nyi.internal (Postfix) with ESMTP id ED4E35C01C6; Fri, 23 Apr 2021 11:14:20 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Fri, 23 Apr 2021 11:14:20 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm3; bh=16wN/jkdXOhB2Qv50Rj4wzhke1a camhUUODlMup47wE=; b=QjqG0OxtWLeYtWmY8wX4D6A9Nso31fxoBbA8g0Sb1ul tE3iabGKEYnU5ck4VOpNgZk5sxI8lGuF5G6vCv5dnN/ncxHSnpGK/MFytsJZLYMC zJHs1jNXmEM9aEQKIli2dYaxZ7Dcn/zeGySG+oMlLNoIOxPcyaDUx6+qZmv7wDDC 9dtyV5yZpXXvhDpRwlPwLmSk0CNmvUee8h43lveX0+htaH9yI2yvaBix1f507EYC TO1YU7Xc95dG0CKeXdU4DR7RsVXiTCy/bViA5JgMBEG+MxEpqc/gFiRRYOOPiAFa 4VAq6E8Ch08rulpNUp+L2Yk89Vn/4KBLZXi8kzQdTSw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=16wN/j kdXOhB2Qv50Rj4wzhke1acamhUUODlMup47wE=; b=vgJLBXgSZujv/8vrKkr+ev GbND0lNsI5i1bG0eoRjDxlLYFbbKleyKW6sFQrzCYBzeI6DHT4W1ZWA9M+YuiZi8 S7bDl+26j0mJjydn/20R8QpOWDgWdbxBJonfXK3Ja0BPjyBzJrk12BvI4xqPT8UD uQsduMq9h9Lji7ApFKLO88ByAHnvf8g/41Q+KL+cknygTrL1qFFoe8958XmLkLa/ mrZRiQg2u7nIilLIToZBZF9uZb6v2fHnmTJfnOstHoiZPy/cXWyziJw99lHRLABG oE/rbe7w7oECYYfMFSBI+/NNbh5uQjM5RICg+0uRIPpZUi4myNJw5EEJybVUHFBg == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrvdduvddgkeeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvffukfhfgggtuggjsehttdertddttddvnecuhfhrohhmpefirhgvghcu mffjuceoghhrvghgsehkrhhorghhrdgtohhmqeenucggtffrrghtthgvrhhnpedvjeeuje efgeevkeejfffgffevjeelueffgeelvefgudduhfffhfeggfevtdetfeenucffohhmrghi nhepshgvthhuphhsrdhhohifnecukfhppeekfedrkeeirdejgedrieegnecuvehluhhsth gvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepghhrvghgsehkrhhorghh rdgtohhm X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 67E271080067; Fri, 23 Apr 2021 11:14:20 -0400 (EDT) Date: Fri, 23 Apr 2021 17:14:18 +0200 From: Greg KH To: Jianxiong Gao Cc: stable@vger.kernel.org Subject: Re: [PATCH v5.10 0/8] preserve DMA offsets when using swiotlb Message-ID: References: <20210405210230.1707074-1-jxgao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Apr 20, 2021 at 04:38:13PM -0700, Jianxiong Gao wrote: > On Wed, Apr 7, 2021 at 5:51 AM Greg KH wrote: > > > > On Mon, Apr 05, 2021 at 09:02:22PM +0000, Jianxiong Gao wrote: > > > Hi all, > > > > > > This series of backports fixes the SWIOTLB library to maintain the > > > page offset when mapping a DMA address. The bug that motivated this > > > patch series manifested when running a 5.4 kernel as a SEV guest with > > > an NVMe device. However, any device that infers information from the > > > page offset and is accessed through the SWIOTLB will benefit from this > > > bug fix. > > > > But this is 5.10, not 5.4, why mention 5.4 here? > Oops. The cover letter shouldn't mention the kernel version. The bug > is present in both 5.4 and 5.10. Sorry for the confusion.> > > And you are backporting a 5.12-rc feature to 5.10, what happened to > > 5.11? > No. The goal is to backport a bug fix to the LTS releases. > > Why not just use 5.12 to get this new feature instead of using an older > > kernel? It's not like this has ever worked before, right? > > > It's true, that a new feature (SEV virtualization) is what motivated > the bug fix. However, I still think this makes sense to backport to > the LTS releases because it does fix a pre-existing bug that may be > impacting pre-existing setups. How? Anything that installed 5.10 when it was released never had this working, they had to move to 5.12 to get that to work. > In particular, while working on these patches, I got the following feedback: > "There are plenty of other hardware designs that rely on dma mapping > not adding offsets that did not exist, e.g. ahci and various RDMA > NICs." I do not understand that statement, how does that pertain to this patch set? confused, greg k-h