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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 2D0EFC433F5 for ; Mon, 20 Sep 2021 17:35:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1998D6339B for ; Mon, 20 Sep 2021 17:35:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348156AbhITRgf (ORCPT ); Mon, 20 Sep 2021 13:36:35 -0400 Received: from mail-ot1-f49.google.com ([209.85.210.49]:45929 "EHLO mail-ot1-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351638AbhITRef (ORCPT ); Mon, 20 Sep 2021 13:34:35 -0400 Received: by mail-ot1-f49.google.com with SMTP id l7-20020a0568302b0700b0051c0181deebso24569598otv.12; Mon, 20 Sep 2021 10:33:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=D/fnKawn3e+PlYXmYSKy1jDEJMKkz3oshJ3rc6YnaMw=; b=uo1aYta0/my5D9xHjBDUZthBcj07VYM+k2Z5wC2RLO9SXtrQTQdNTIIL+pjXBRiUpX dsO4SIZ0oJZibmxPIazgN1fNykjGh1zFN5kCOQTVChnUgLfh2YpA0DOrEE1jMX/pSwiz qYdVfjte64vmO30vJLJj3t5spOiGdwpvITyu3vjdrlHdEUbBC0cRZnofadPGeQgig7Q2 trN6bKiIPA91MBit6k7yjULGJnzDD21kPpPk2EuFVCh24pZf9LJ6Yxm04FQGkF33/Re8 eI1KTfNsTFw+x1+ysdnIziwHmO7Al15k61HA1zhFnj34qFSFTBRiAtzPy4k/K+TGTGqg PCYQ== X-Gm-Message-State: AOAM531eWmIJcwNYm46nw/IOrL5ycn9r+giz+18rKDzPsl0Fi4/h1+J7 2w08M6JlfYKhNNV+pjLciThobCXboIazIoi+vvg= X-Google-Smtp-Source: ABdhPJzJCYEFPitZMZzYluNMtLoOtNASKL6dUFfbGgBbEnA/TfjStj/Yb08kNaZPL2SgbMtzdMvOTkrcrIWJAA/2jzg= X-Received: by 2002:a9d:4d93:: with SMTP id u19mr22249291otk.86.1632159187086; Mon, 20 Sep 2021 10:33:07 -0700 (PDT) MIME-Version: 1.0 References: <20210910122820.26886-1-justin.he@arm.com> <20210910143223.6705-1-justin.he@arm.com> <20210916160827.GA4525@lpieralisi> <20210920170055.GA13861@lpieralisi> In-Reply-To: <20210920170055.GA13861@lpieralisi> From: "Rafael J. Wysocki" Date: Mon, 20 Sep 2021 19:32:56 +0200 Message-ID: Subject: Re: [PATCH v2] Revert "ACPI: Add memory semantics to acpi_os_map_memory()" To: Lorenzo Pieralisi Cc: Ard Biesheuvel , Rafael Wysocki , "Rafael J. Wysocki" , Jia He , Will Deacon , Len Brown , Robert Moore , Erik Kaneda , Linux ARM , Linux Kernel Mailing List , ACPI Devel Maling List , "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" , Hanjun Guo , Catalin Marinas , Harb Abdulhamid Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Mon, Sep 20, 2021 at 7:03 PM Lorenzo Pieralisi wrote: > > On Thu, Sep 16, 2021 at 05:08:27PM +0100, Lorenzo Pieralisi wrote: > > On Fri, Sep 10, 2021 at 07:28:49PM +0200, Ard Biesheuvel wrote: > > > On Fri, 10 Sept 2021 at 16:32, Jia He wrote: > > > > > > > > This reverts commit 437b38c51162f8b87beb28a833c4d5dc85fa864e. > > > > > > > > After this commit, a boot panic is alway hit on an Ampere EMAG server > > > > with call trace as follows: > > > > Internal error: synchronous external abort: 96000410 [#1] SMP > > > > Modules linked in: > > > > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0+ #462 > > > > Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 0.14 02/22/2019 > > > > pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > > > > [...snip...] > > > > Call trace: > > > > acpi_ex_system_memory_space_handler+0x26c/0x2c8 > > > > acpi_ev_address_space_dispatch+0x228/0x2c4 > > > > acpi_ex_access_region+0x114/0x268 > > > > acpi_ex_field_datum_io+0x128/0x1b8 > > > > acpi_ex_extract_from_field+0x14c/0x2ac > > > > acpi_ex_read_data_from_field+0x190/0x1b8 > > > > acpi_ex_resolve_node_to_value+0x1ec/0x288 > > > > acpi_ex_resolve_to_value+0x250/0x274 > > > > acpi_ds_evaluate_name_path+0xac/0x124 > > > > acpi_ds_exec_end_op+0x90/0x410 > > > > acpi_ps_parse_loop+0x4ac/0x5d8 > > > > acpi_ps_parse_aml+0xe0/0x2c8 > > > > acpi_ps_execute_method+0x19c/0x1ac > > > > acpi_ns_evaluate+0x1f8/0x26c > > > > acpi_ns_init_one_device+0x104/0x140 > > > > acpi_ns_walk_namespace+0x158/0x1d0 > > > > acpi_ns_initialize_devices+0x194/0x218 > > > > acpi_initialize_objects+0x48/0x50 > > > > acpi_init+0xe0/0x498 > > > > > > > > As mentioned by Lorenzo: > > > > "We are forcing memory semantics mappings to PROT_NORMAL_NC, which > > > > eMAG does not like at all and I'd need to understand why. It looks > > > > like the issue happen in SystemMemory Opregion handler." > > > > > > > > Hence just revert it before everything is clear. > > > > > > > > > > Can we try to find the root cause first? -rc1 is not even out yet, and > > > reverting it now means we can not resubmit it until the next merge > > > window. > > > > I am waiting to debug this on an eMAG but I noticed something that > > I wanted to bring up. > > > > SystemMemory Operation region handler - ie > > > > acpi_ex_system_memory_space_handler() > > > > maps the Operation Region (that AFAICS is MMIO, it is _not_ memory) > > with acpi_os_map_memory() and I believe that's what is causing this > > bug. > > > > On the other hand, acpi_os_map_generic_address(), to handle spaceid > > ACPI_ADR_SPACE_SYSTEM_MEMORY, uses acpi_os_map_iomem() that is more > > in line with my expectations. > > Hi Rafael, > > I wanted to ask please if you have any insights on why > > (1) acpi_ex_system_memory_space_handler() > (2) acpi_os_map_generic_address() > > Use two different calls to map memory for the _same_ address space ID > (SystemMemory). > > (3) acpi_os_map_memory() > vs > (4) acpi_os_map_iomem() I don't really have a good answer here. On x86 this doesn't really matter and that's where acpi_ex_system_memory_space_handler() was first introduced. It is not only used for IOMEM (there are SystemMemory operation regions in RAM), but since it may be in IOMEM, it should assume so. > I am struggling to understand why (1) uses (3) ("memory semantics") when > (2) uses (4) - it is actually unclear how the distinction between > the two mapping APIs is to be drawn and on what basis one should > choose which one to use. > > I am still waiting to grab some HW to debug this report but the issue > here is that we are mapping an OpRegion SystemMemory with (3) in the > memory space handler and given the patch we are reverting we end up > mapping the operation region with normal non-cacheable memory attributes > that probably the physical address range behind the OpRegion does not > support. If that is the case, there needs to be a mechanism to decide what kind of mapping to use for SystemMemory operation regions based on the type of physical memory the address range in question is located in. > > Question is: is the mapping in acpi_ex_system_memory_space_handler() > > wrong (and should be patched with acpi_os_map_iomem() ?) > > > > On x86 this should not change a thing, on ARM it would. > > > > I don't think it is right to map SystemMemory Operation regions with > > memory semantics but on the other hand, other than the EFI memory map, > > there is nothing we can do to determine what a SystemMemory Operation > > region address space actually represents. > > > > Thoughts ? Before embarking on patching > > > > acpi_ex_system_memory_space_handler() > > > > I want to make sure my understanding of the SystemMemory space is > > correct, comments welcome. > > > > I will pinpoint the trigger for this bug shortly and before doing > > anything else. > > > > Thanks, > > Lorenzo