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[23.128.96.18]) by mx.google.com with ESMTP id e28si2151096ioc.25.2021.09.22.04.12.44; Wed, 22 Sep 2021 04:13:03 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=Dcx93AOY; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235428AbhIVLNL (ORCPT + 99 others); Wed, 22 Sep 2021 07:13:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:34520 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235424AbhIVLNI (ORCPT ); Wed, 22 Sep 2021 07:13:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B91A3611C0; Wed, 22 Sep 2021 11:11:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1632309098; bh=NnGf5aanVMI9Q2QeFfrZ/JPAh/XVIHVqkQ7T6ebXJJ0=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=Dcx93AOYCAeK8ldIhELD+2bl1FpqFopZnW1zfXEiMvH6KCjgcCIVnV/or16NekSUp 4oa+rED5QWprtkKiPzTIbOKpl5HNmDsQp2iAwwfxQkV7XiG5q6JajCqznDg4BK7KbV eB0BMXS9FcHrT0x6uQC7qQkSPTZOxFGAJ1lT0p4zWrDSVlPBKo5NZykeltOsKh6IEX Y1fcqJ4cSSnI6WoJaeAZBX5jMMuYDJtwip9onLBSAHemGrpGs5fCow3fId5ErAbWW1 ZmPULABxQTemNn6QrtiopM6d5zOXhsxtG1XAbynXUfPvjGNCxwOfJvG6Rh6tTrDO5U 6XfB8HMYCIdww== Received: by mail-oi1-f178.google.com with SMTP id s69so3773182oie.13; Wed, 22 Sep 2021 04:11:38 -0700 (PDT) X-Gm-Message-State: AOAM5334OrtXBehHgTsFgml2/W/64m6NBmHym842APlr9MACSNBcV/hS UrQ/guPhM4c/W+RPc5brejlskwruNoAtm2HtX4g= X-Received: by 2002:aca:3114:: with SMTP id x20mr7585573oix.174.1632309098052; Wed, 22 Sep 2021 04:11:38 -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> <20210921100512.GA28390@lpieralisi> In-Reply-To: <20210921100512.GA28390@lpieralisi> From: Ard Biesheuvel Date: Wed, 22 Sep 2021 13:11:26 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2] Revert "ACPI: Add memory semantics to acpi_os_map_memory()" To: Lorenzo Pieralisi Cc: "Rafael J. Wysocki" , 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-kernel@vger.kernel.org On Tue, 21 Sept 2021 at 12:05, Lorenzo Pieralisi wrote: > > On Mon, Sep 20, 2021 at 07:32:56PM +0200, Rafael J. Wysocki wrote: > > 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. > > Thank you Rafael. The mechanism we are currently relying on is the EFI > memory map but if the Opregion address is not described there then we > are left with a default choice to make (theoretically I may also parse > all _CRS in the namespace to find whether a resource include the > Opregion and I may infer attributes from the _CRS resource entry). > I'm not sure that would help, as I would expected the memory described by _CRS to be mostly mutually exclusive from memory used by OpRegions. > Maybe we should update the ACPI specs to enforce it; with current > firmware the idea of using the OS expected *usage* of memory (ie > memory vs IO) described by the mapping function prototype can't work > as this revert shows (even though it would be better if I manage > to find what the precise issue is). > > We can't map something with specific attributes if we don't know > whether the physical address space backing the region supports it. > We don't have a a safe default in either direction, so I agree this is a hole in the specs. > I am left with little choice: I assume the best thing I could do > to fix the original bug is to use ioremap_* in acpi_data_show() > instead of acpi_os_map/unmap_memory() to map that memory with > specific attributes (for BERT error regions, they must be RAM > so, _hopefully_, we know it can be mapped with eg normal memory > mappings). > > Thoughts ? > One thing I just realized is that the EFI memory map is not a complete solution to begin with, as it may not cover hot/coldplugged memory regions that are only described via ACPI. Did you make any progress with the eMAG?