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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 E5D66C47DD9 for ; Fri, 22 Mar 2024 19:53:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=xxSOiiz7DI+h9AylzJ/2OjVbLQvpp2wNP3i7AuoMCww=; b=zYu2GxziTLxmnk PhCc4mFSaKohFSQUJYjfX4PXK9iITyhantA/TXlXXsHkPyh8HRkQ2sj04s39asoiuoG5UfRKP5hXL uUIESpycE3Tc6AuO0mY+dyRdu89b+9IGa3euKLvfLCLFlD7d36BWu7jIamgwfsrJ/xXDP91339WM+ zG/93Ao5QtSwBFFkevBditMlY3N3Bhp6qOMb5JnHxZcOfwZufowJjyMCzK8SQ8zT6GtJFqW8GpiSi CtVLMESIsHta2qUby4gO8DUONT5uEca7Mo73YbS23JVaqquQXSdUPCC/QeUC8CkvUGVEbdsqOl8sb YSHyD+cRhivPMHnNU6Ag==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rnkwo-00000008YMI-46Qw; Fri, 22 Mar 2024 19:53:02 +0000 Received: from fout3-smtp.messagingengine.com ([103.168.172.146]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rnkwl-00000008YLa-3bHM for linux-arm-kernel@lists.infradead.org; Fri, 22 Mar 2024 19:53:01 +0000 Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailfout.nyi.internal (Postfix) with ESMTP id 147B913800EE; Fri, 22 Mar 2024 15:52:57 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Fri, 22 Mar 2024 15:52:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=tyhicks.com; h= cc:cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:subject :subject:to:to; s=fm1; t=1711137177; x=1711223577; bh=SDe9rNbXis 2QKNa9pGytu06HZGUqYjzBkgt7/9/1dz8=; b=HvCYZyr5O3L/UydCTC5xfpLLy3 KqBlUl4a1x1yS2iMt+r4mpd7R0OzkQMWuqUlCOm879HnJaGq65Trchp+6wc5fI92 U7oiN7k1K10otaVkFjDuFz8ul528JNpjl+ehVIEIAB6Oamp3J0uqGOaE5vtul276 MvwMKoi7TgeRmO3d0RLaq9h27YrlsfutW75c8FAF/Z/UOFUZB8PX36bCeyvZlc30 5ZQlOZqWXmQ4vmWTVREIb+AQdLPy6jB5jLTcVGKHZKWHo5UMrw7+B+HH48Yx3LXj bwlQ/+SLZAlyaCb+aXBvFw0cyz+SN/OeeKJDq4LwLb8GtlP0rv6CB7fpIc4g== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:subject:subject:to :to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm2; t=1711137177; x=1711223577; bh=SDe9rNbXis2QKNa9pGytu06HZGUq YjzBkgt7/9/1dz8=; b=Rj6wfpM1eqRiPgpB3/qkn1p4txZDVo3Gcuix4+CvR0s0 LyMFGwXmfdGrD8hg5u8sB6gLeqOyvon3JJRQjiURCIeqkmOV880Qo8hkfN3zZvX6 7U6C0KlTwR+BNYRdXDSKmAFTH8l62k2cgmfDIy/G1qiwCigQFxtr5DFJLi+D0N6L K/bUC+LjfWJ5mE1jEAhu6SzeyOLY3UYM1igfZO5ObAt4NNwkBDIza1ILhm7F/1GT 7pOOVDQBXd5uG3vH4AhdCHHbPAOzK4dR82lVdByL7MVlP3gkA/n4wR2aqUqkFfCK +P/8t/uGREghrQYpvI6eAB2BbrdkqCxVRGlhJvufwQ== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvledruddtvddgieeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepvfihlhgv rhcujfhitghkshcuoegtohguvgesthihhhhitghkshdrtghomheqnecuggftrfgrthhtvg hrnhepvdehvddttdfhfefhtdfgleehfeeggfdujeeuveekudevkedvgeejtddtfefgleei necuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomheptghoug gvsehthihhihgtkhhsrdgtohhm X-ME-Proxy: Feedback-ID: i78e14604:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 22 Mar 2024 15:52:55 -0400 (EDT) Date: Fri, 22 Mar 2024 14:52:52 -0500 From: Tyler Hicks To: Will Deacon Cc: Jason Gunthorpe , Robin Murphy , Jerry Snitselaar , linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Dexuan Cui , Easwar Hariharan Subject: Re: Why is the ARM SMMU v1/v2 put into bypass mode on kexec? Message-ID: References: <120d0dec-450f-41f8-9e05-fd763e84f6dd@arm.com> <20240319154756.GB2901@willie-the-truck> <20240319175007.GC66976@ziepe.ca> <20240322155529.GE5634@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240322155529.GE5634@willie-the-truck> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240322_125300_055521_742F7CC6 X-CRM114-Status: GOOD ( 16.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2024-03-22 15:55:29, Will Deacon wrote: > Hey Jason, > > On Tue, Mar 19, 2024 at 02:50:07PM -0300, Jason Gunthorpe wrote: > > On Tue, Mar 19, 2024 at 03:47:56PM +0000, Will Deacon wrote: > > > > > Right, it's hard to win if DMA-active devices weren't quiesced properly > > > by the outgoing kernel. Either the SMMU was left in abort (leading to the > > > problems you list above) or the SMMU is left in bypass (leading to possible > > > data corruption). Which is better? > > > > For whatever reason (and I really don't like this design) alot of work > > was done on x86 so that device continues to work as-was right up until > > the crash kernel does the first DMA operation. Including having the > > crash kernel non disruptively inherit and retain the IOMMU > > configuration. (eg see translation_pre_enabled() stuff in intel > > driver) > > Right, I'm also not thrilled about trying to implement that :) > What we have at the moment seems to be good enough to avoid folks > complaining about it. > > For the case Tyler is reporting, though, I _think_ it's just a standard > kexec() rather than a crashkernel. That's correct. Tyler _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel