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=-8.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 A4DC4C07E99 for ; Thu, 8 Jul 2021 16:44:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F2D76142C for ; Thu, 8 Jul 2021 16:44:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229650AbhGHQrN (ORCPT ); Thu, 8 Jul 2021 12:47:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:38410 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229524AbhGHQrN (ORCPT ); Thu, 8 Jul 2021 12:47:13 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 88F256145A; Thu, 8 Jul 2021 16:44:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625762671; bh=W3zJ1dUIVfwK2RD5Gb/pjjaY8IvTpKuqVuwPdbuz25M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Sp+30VCoqVzKdRCHxsdjheJ32Al4GyKkdqY67UI3HBglP9/4ElBHuP/C2H/FyWKo7 e/R4/9B3d7vhaPNlh1DPVXpIf7uT6p/REBIACdKpJwJF9GZS42ymRBAxS0kVUi63dX LFzIygW0HZtu2Ulg0IazOQ0jJMqOOsCWNLsNFVLNWlAdaw+e6puTS7FlMwyfD5gEdI lFB3Rrin6g2B0nXBBJNO+PUuvd4DpkVlBGoDw/jR5Tje1HakbrKaEjYhMjAxMq0G0/ 9JUb/J7ll5Lxx3f7sEDifcv8wjoDYV7KpD0n+YA4MYDlWDIvbopDufBoyo/NtyqWxC FAtOTP/W4ikEQ== Date: Thu, 8 Jul 2021 17:44:19 +0100 From: Will Deacon To: Nathan Chancellor Cc: Robin Murphy , Christoph Hellwig , heikki.krogerus@linux.intel.com, thomas.hellstrom@linux.intel.com, peterz@infradead.org, benh@kernel.crashing.org, joonas.lahtinen@linux.intel.com, dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk, grant.likely@arm.com, paulus@samba.org, Frank Rowand , mingo@kernel.org, Stefano Stabellini , Saravana Kannan , mpe@ellerman.id.au, "Rafael J . Wysocki" , Bartosz Golaszewski , bskeggs@redhat.com, linux-pci@vger.kernel.org, xen-devel@lists.xenproject.org, Thierry Reding , intel-gfx@lists.freedesktop.org, matthew.auld@intel.com, linux-devicetree , Jianxiong Gao , Daniel Vetter , Konrad Rzeszutek Wilk , maarten.lankhorst@linux.intel.com, airlied@linux.ie, Dan Williams , linuxppc-dev@lists.ozlabs.org, jani.nikula@linux.intel.com, Rob Herring , rodrigo.vivi@intel.com, Bjorn Helgaas , Claire Chang , boris.ostrovsky@oracle.com, Andy Shevchenko , jgross@suse.com, Nicolas Boichat , Greg KH , Randy Dunlap , Qian Cai , lkml , "list@263.net:IOMMU DRIVERS" , Jim Quinlan , xypron.glpk@gmx.de, Tom Lendacky , bauerman@linux.ibm.com Subject: Re: [PATCH v15 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing Message-ID: <20210708164418.GB23598@willie-the-truck> References: <0f7bd903-e309-94a0-21d7-f0e8e9546018@arm.com> <20210705190352.GA19461@willie-the-truck> <20210706044848.GA13640@lst.de> <20210706132422.GA20327@willie-the-truck> <20210706140513.GA26498@lst.de> <20210706170657.GD20750@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Jul 06, 2021 at 12:14:16PM -0700, Nathan Chancellor wrote: > On 7/6/2021 10:06 AM, Will Deacon wrote: > > On Tue, Jul 06, 2021 at 04:39:11PM +0100, Robin Murphy wrote: > > > On 2021-07-06 15:05, Christoph Hellwig wrote: > > > > On Tue, Jul 06, 2021 at 03:01:04PM +0100, Robin Murphy wrote: > > > > > FWIW I was pondering the question of whether to do something along those > > > > > lines or just scrap the default assignment entirely, so since I hadn't got > > > > > round to saying that I've gone ahead and hacked up the alternative > > > > > (similarly untested) for comparison :) > > > > > > > > > > TBH I'm still not sure which one I prefer... > > > > > > > > Claire did implement something like your suggestion originally, but > > > > I don't really like it as it doesn't scale for adding multiple global > > > > pools, e.g. for the 64-bit addressable one for the various encrypted > > > > secure guest schemes. > > > > > > Ah yes, that had slipped my mind, and it's a fair point indeed. Since we're > > > not concerned with a minimal fix for backports anyway I'm more than happy to > > > focus on Will's approach. Another thing is that that looks to take us a > > > quiet step closer to the possibility of dynamically resizing a SWIOTLB pool, > > > which is something that some of the hypervisor protection schemes looking to > > > build on top of this series may want to explore at some point. > > > > Ok, I'll split that nasty diff I posted up into a reviewable series and we > > can take it from there. > > For what it's worth, I attempted to boot Will's diff on top of Konrad's > devel/for-linus-5.14 and it did not work; in fact, I got no output on my > monitor period, even with earlyprintk=, and I do not think this machine has > a serial console. Looking back at the diff, I completely messed up swiotlb_exit() by mixing up physical and virtual addresses. > Robin's fix does work, it survived ten reboots with no issues getting to X > and I do not see the KASAN and slub debug messages anymore but I understand > that this is not the preferred solution it seems (although Konrad did want > to know if it works). > > I am happy to test any further patches or follow ups as needed, just keep me > on CC. Cheers. Since this isn't 5.14 material any more, I'll CC you on a series next week. Will