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=-8.9 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=unavailable 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 49AC9C07E9B for ; Mon, 5 Jul 2021 19:04:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DEF461986 for ; Mon, 5 Jul 2021 19:04:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229910AbhGETGm (ORCPT ); Mon, 5 Jul 2021 15:06:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:36488 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229770AbhGETGm (ORCPT ); Mon, 5 Jul 2021 15:06:42 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3D07161978; Mon, 5 Jul 2021 19:03:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625511844; bh=o012umLuvyjggdb73nB1nx1kOYsPv1SNeUIs18hDcAw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GRwf1cGaUQnGNSK48BMiS8/L53RP5G/QW+0L7WarqJg3vdXhPi76IMHEfxJBcIPa3 O/IVWGS61Gw63qZ6P/lu+E1G7lOjBRQgMMYZUlxciRBcXpXeaEm0Nt8VlI20vyORW0 5Yt77iWQoVMzfxA0eNrndYooJS41ndFVzjZWCxmusBkktvSuT3rDjxcvXFg+FyE3zq Tiys8WKwLxyKU0wwkmXs/VX0V/xsNc/cZvd76dhCDw80UkiEfPmHKQyUCziEG4n9+X zngjj2Bp6GquWJbjoHo8XOCLo60dYdheBX5hvWTEA+kb21c5xQf9Khdj2j/E3DZMQq mzeeqFIjv4raA== Date: Mon, 5 Jul 2021 20:03:52 +0100 From: Will Deacon To: Nathan Chancellor Cc: Robin Murphy , Claire Chang , Rob Herring , mpe@ellerman.id.au, Joerg Roedel , Frank Rowand , Konrad Rzeszutek Wilk , boris.ostrovsky@oracle.com, jgross@suse.com, Christoph Hellwig , Marek Szyprowski , benh@kernel.crashing.org, paulus@samba.org, "list@263.net:IOMMU DRIVERS" , Stefano Stabellini , grant.likely@arm.com, xypron.glpk@gmx.de, Thierry Reding , mingo@kernel.org, bauerman@linux.ibm.com, peterz@infradead.org, Greg KH , Saravana Kannan , "Rafael J . Wysocki" , heikki.krogerus@linux.intel.com, Andy Shevchenko , Randy Dunlap , Dan Williams , Bartosz Golaszewski , linux-devicetree , lkml , linuxppc-dev@lists.ozlabs.org, xen-devel@lists.xenproject.org, Nicolas Boichat , Jim Quinlan , Tomasz Figa , bskeggs@redhat.com, Bjorn Helgaas , chris@chris-wilson.co.uk, Daniel Vetter , airlied@linux.ie, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com, Jianxiong Gao , joonas.lahtinen@linux.intel.com, linux-pci@vger.kernel.org, maarten.lankhorst@linux.intel.com, matthew.auld@intel.com, rodrigo.vivi@intel.com, thomas.hellstrom@linux.intel.com, Tom Lendacky , Qian Cai Subject: Re: [PATCH v15 06/12] swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing Message-ID: <20210705190352.GA19461@willie-the-truck> References: <20210624155526.2775863-7-tientzu@chromium.org> <20210630114348.GA8383@willie-the-truck> <20210701074045.GA9436@willie-the-truck> <20210702135856.GB11132@willie-the-truck> <0f7bd903-e309-94a0-21d7-f0e8e9546018@arm.com> 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-kernel@vger.kernel.org Hi Nathan, I may have just spotted something in these logs... On Fri, Jul 02, 2021 at 10:55:17PM -0700, Nathan Chancellor wrote: > [ 2.340956] pci 0000:0c:00.1: Adding to iommu group 4 > [ 2.340996] pci 0000:0c:00.2: Adding to iommu group 4 > [ 2.341038] pci 0000:0c:00.3: Adding to iommu group 4 > [ 2.341078] pci 0000:0c:00.4: Adding to iommu group 4 > [ 2.341122] pci 0000:0c:00.6: Adding to iommu group 4 > [ 2.341163] pci 0000:0d:00.0: Adding to iommu group 4 > [ 2.341203] pci 0000:0d:00.1: Adding to iommu group 4 > [ 2.361821] pci 0000:00:00.2: AMD-Vi: Found IOMMU cap 0x40 > [ 2.361839] pci 0000:00:00.2: AMD-Vi: Extended features (0x206d73ef22254ade): > [ 2.361846] PPR X2APIC NX GT IA GA PC GA_vAPIC > [ 2.361861] AMD-Vi: Interrupt remapping enabled > [ 2.361865] AMD-Vi: Virtual APIC enabled > [ 2.361870] AMD-Vi: X2APIC enabled > [ 2.362272] AMD-Vi: Lazy IO/TLB flushing enabled So at this point, the AMD IOMMU driver does: swiotlb = (iommu_default_passthrough() || sme_me_mask) ? 1 : 0; where 'swiotlb' is a global variable indicating whether or not swiotlb is in use. It's picked up a bit later on by pci_swiotlb_late_init(), which will call swiotlb_exit() if 'swiotlb' is false. Now, that used to work fine, because swiotlb_exit() clears 'io_tlb_default_mem' to NULL, but now with the restricted DMA changes, I think that all the devices which have successfully probed beforehand will have stale pointers to the freed structure in their 'dev->dma_io_tlb_mem' field. Will