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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 2D021C433F5 for ; Wed, 22 Sep 2021 13:14:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D537A61100 for ; Wed, 22 Sep 2021 13:14:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D537A61100 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=VdaplnaD3lgaQiHeoDv1l++XcVfemZtZ10nye0l59jY=; b=l6kUuzPva5Tm+Q KPVgb8NWeNklYps8MhapT/hH1l/EpA9srBgeLOqeuDEjPhE9n4IPtix8IETvHQSkXCgtJYE6Aaafr P/GXcLlug8/yUL7te2r+G7Db51amuvz3mDQZXocJltyURk8W1ksOSPdr01Rri5tuJPoa45PgxCrtX vJgnOgka5Ag5pg/G3YkpD8DdODF6OfYVt+Nmz7Suo8D1mon31DI3zoGMp6m8HEpYgNs4cUVgUCm8S gJKRtgyHRBYXAQ8DI/+GpRUXoQ/u/VMUvAT/yILnT1LpB+/X2HtTKdXZb5e36ZiHqqw7CZTVKe1wj viX7cl32T/UfyeM63ahA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mT22K-008Yjb-Ca; Wed, 22 Sep 2021 13:11:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mT1xv-008XAF-Jv for linux-arm-kernel@lists.infradead.org; Wed, 22 Sep 2021 13:07:16 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 627D711B3; Wed, 22 Sep 2021 06:07:07 -0700 (PDT) Received: from lpieralisi (e121166-lin.cambridge.arm.com [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 55E303F40C; Wed, 22 Sep 2021 06:07:05 -0700 (PDT) Date: Wed, 22 Sep 2021 14:07:00 +0100 From: Lorenzo Pieralisi To: Ard Biesheuvel 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 Subject: Re: [PATCH v2] Revert "ACPI: Add memory semantics to acpi_os_map_memory()" Message-ID: <20210922130700.GA20981@lpieralisi> References: <20210910122820.26886-1-justin.he@arm.com> <20210910143223.6705-1-justin.he@arm.com> <20210916160827.GA4525@lpieralisi> <20210920170055.GA13861@lpieralisi> <20210921100512.GA28390@lpieralisi> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210922_060711_877349_536826F3 X-CRM114-Status: GOOD ( 58.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Sep 22, 2021 at 01:11:26PM +0200, Ard Biesheuvel wrote: > 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? I manage to get the ACPI tables dump. The fault is triggered on a SystemMemory OPregion access (FYI - should be a reset register), probably (but on this only Ampere can help us) because the MMIO range in question does not support the AXI attributes assigned by the NormalNC mapping. I believe mapping SystemMemory Opregions as NormalNC does not make much sense anyway. The UEFI specs seem to hint that the ACPI Op-region cacheability attributes must be determined through the UEFI memory map, not sure whether that means that the OpRegion itself _must_ be in the EFI memory map. I believe we need to go on with the revert and find a way to fix the BERT error region mappings, to make them NormalNC so that we can do unaligned accesses on them. What to do specs side - to be debated, we have to do something because it is impossible to handle it sensibly otherwise. Lorenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel