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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 5351BC433E0 for ; Sat, 1 Aug 2020 08:57:17 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1557C20716 for ; Sat, 1 Aug 2020 08:57:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1557C20716 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id C491A20365; Sat, 1 Aug 2020 08:57:16 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 3Uqi-5Ws87dV; Sat, 1 Aug 2020 08:57:15 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 882532036B; Sat, 1 Aug 2020 08:57:15 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 45CF1C0050; Sat, 1 Aug 2020 08:57:15 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 10FA4C004D for ; Sat, 1 Aug 2020 08:57:13 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id E144187841 for ; Sat, 1 Aug 2020 08:57:12 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 48Y1U40Q7NvV for ; Sat, 1 Aug 2020 08:57:11 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by whitealder.osuosl.org (Postfix) with ESMTPS id 9EC18889BA for ; Sat, 1 Aug 2020 08:57:11 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 2175668C4E; Sat, 1 Aug 2020 10:57:07 +0200 (CEST) Date: Sat, 1 Aug 2020 10:57:06 +0200 From: Christoph Hellwig To: David Rientjes , Linus Torvalds Subject: revert scope for 5.8, was Re: dma-pool fixes Message-ID: <20200801085706.GA2991@lst.de> References: <20200728124114.GA4865@lst.de> <20200728153055.GA16701@lst.de> <18a3b93cc5ba3e0e39ae1b14759ce31121d54045.camel@suse.de> <20200731130903.GA31110@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Amit Pundir , jeremy.linton@arm.com, iommu@lists.linux-foundation.org, linux-rpi-kernel@lists.infradead.org, Robin Murphy , Christoph Hellwig 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" On Sat, Aug 01, 2020 at 01:20:07AM -0700, David Rientjes wrote: > To follow-up on this, the introduction of the DMA atomic pools in 5.8 > fixes an issue for any AMD SEV enabled guest that has a driver that > requires atomic DMA allocations (for us, nvme) because runtime decryption > of memory allocated through the DMA API may block. This manifests itself > as "sleeping in invalid context" BUGs for any confidential VM user in > cloud. > > I unfortunately don't have Amit's device to be able to independently debug > this issue and certainly could not have done a better job at working the > bug than Nicolas and Christoph have done so far. I'm as baffled by the > results as anybody else. > > I fully understand the no regressions policy. I'd also ask that we > consider that *all* SEV guests are currently broken if they use nvme or > any other driver that does atomic DMA allocations. It's an extremely > serious issue for cloud. If there is *anything* that I can do to make > forward progress on this issue for 5.8, including some of the workarounds > above that Amit requested, I'd be very happy to help. Christoph will make > the right decision for DMA in 5.8, but I simply wanted to state how > critical working SEV guests are to users. I'm between a rock and a hard place here. If we simply want to revert commits as-is to make sure both the Raspberry Pi 4 and thone phone do not regress we'll have to go all the way back and revert the whole SEV pool support. I could try to manual revert of the multiple pool support, but it is very late for that. Or maybe Linus has decided to cut a -rc8 which would give us a little more time. - _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu