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=-9.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 903ACC433EF for ; Thu, 23 Sep 2021 12:55:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CEA461019 for ; Thu, 23 Sep 2021 12:55:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241000AbhIWM4h (ORCPT ); Thu, 23 Sep 2021 08:56:37 -0400 Received: from mail-ot1-f45.google.com ([209.85.210.45]:33325 "EHLO mail-ot1-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240787AbhIWM4e (ORCPT ); Thu, 23 Sep 2021 08:56:34 -0400 Received: by mail-ot1-f45.google.com with SMTP id c42-20020a05683034aa00b0051f4b99c40cso8464420otu.0; Thu, 23 Sep 2021 05:55:03 -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=9cnE91Z/Nvkblt8KBxlBOz53Y6ULkVoI6AYMgns74AQ=; b=yqKS/r8R2nGhZknhJArHXXEPv40WzYB6FXPozTajea7bPtIA+bQ6z5wyphkCLuBZ5i O0Z1mlF4NQI5zqn5G6lnKeI8OeTpQjg7O3r4aQsapkfh+xH8VL3eHmvjXquJo7GSAX9a CMHZa6KJ9fqrgSYt/sD25KzSBY5w/EhdfjkpmjoRKIaoLOrww2KjaU5HqjrT7M/nrvWu eMbK0j9VbRCfVE/IjEIfeAlNiC5es2yymzWf5j6/oOsmYh98mu2yddL+8Q6e+FHrmbEa Q7m99wyuKx+TobKVIDu0QeurvzQEEEz5tcRKU86QEi7vYiJ2fmzCUULv7OG3Tjjpj35s gFAw== X-Gm-Message-State: AOAM533uwXCyAOfxV0MraB3X/Vb5Hbz156yxErPdxU7nehAglEn5rNdP fPtu5r6uoc/HswD49JhFSW/O9zN8zRXwwXvT4/k= X-Google-Smtp-Source: ABdhPJy+DM/7fT9mdBRiBQ1UqkGSyZLL8dWzJQl/kV0NQnaajz48gdaoaHkrbTe8M5Xt/wAgkOMXK6u6ADeQd59vYFI= X-Received: by 2002:a05:6830:165a:: with SMTP id h26mr4285920otr.301.1632401703209; Thu, 23 Sep 2021 05:55:03 -0700 (PDT) MIME-Version: 1.0 References: <20210910122820.26886-1-justin.he@arm.com> <20210910143223.6705-1-justin.he@arm.com> <20210922163336.GA24633@lpieralisi> <56147a0b8b9fba46@bloch.sibelius.xs4all.nl> <20210923094031.GA6454@lpieralisi> <56147c6e73afe9f6@bloch.sibelius.xs4all.nl> In-Reply-To: <56147c6e73afe9f6@bloch.sibelius.xs4all.nl> From: "Rafael J. Wysocki" Date: Thu, 23 Sep 2021 14:54:52 +0200 Message-ID: Subject: Re: [PATCH v2] Revert "ACPI: Add memory semantics to acpi_os_map_memory()" To: Mark Kettenis Cc: "Rafael J. Wysocki" , Lorenzo Pieralisi , Jia He , Harb Abdulhamid , Will Deacon , Len Brown , Robert Moore , Erik Kaneda , Linux ARM , Linux Kernel Mailing List , ACPI Devel Maling List , "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" , Ard Biesheuvel , Hanjun Guo , Catalin Marinas , Rafael Wysocki Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Thu, Sep 23, 2021 at 2:26 PM Mark Kettenis wrote: > > > From: "Rafael J. Wysocki" > > Date: Thu, 23 Sep 2021 13:05:05 +0200 > > > > On Thu, Sep 23, 2021 at 11:40 AM Lorenzo Pieralisi > > wrote: > > > > > > On Thu, Sep 23, 2021 at 01:09:58AM +0200, Mark Kettenis wrote: > > > > > Date: Wed, 22 Sep 2021 17:33:36 +0100 > > > > > From: Lorenzo Pieralisi > > > > > > > > > > On Fri, Sep 10, 2021 at 10:32:23PM +0800, 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. > > > > > > > > > > > > Fixes: 437b38c51162 ("ACPI: Add memory semantics to acpi_os_map_memory()") > > > > > > Cc: Lorenzo Pieralisi > > > > > > Cc: Ard Biesheuvel > > > > > > Cc: Hanjun Guo > > > > > > Cc: Catalin Marinas > > > > > > Cc: Rafael J. Wysocki > > > > > > Cc: Harb Abdulhamid > > > > > > > > > > > > Signed-off-by: Jia He > > > > > > > > > > Rewrote the commit log, please take the patch below and repost > > > > > it as a v3. > > > > > > > > > > It would still be great if Ampere can help us understand why > > > > > the NormalNC attributes trigger a sync abort on the opregion > > > > > before merging it. > > > > > > > > To be honest, I don't think you really need an explanation from Ampere > > > > here. Mapping a part of the address space that doesn't provide memory > > > > semantics with NormalNC attributes is wrong and triggering a sync > > > > abort in that case is way better than silently ignoring the access. > > > > > > That's understood and that's what I explained in the revert commit > > > log, no question about it. > > > > > > I was just asking to confirm if that's what's actually happening. > > > > > > > Putting my OpenBSD hat on (where we have our own ACPI OSPM > > > > implementation) I must say that we always interpreted SystemMemory as > > > > memory mapped IO and I think that is a logical choice as SystemIO is > > > > used for (non-memory mapped) IO. And I'd say that the ACPI OSPM code > > > > should make sure that it uses properly aligned access to any Field > > > > object that doesn't use AnyAcc as its access type. Even on x86! And > > > > I'd say that AML that uses AnyAcc fields for SystemMemory OpRegions on > > > > arm64 is buggy. > > > > > > > > But maybe relaxing this when the EFI memory map indicates that the > > > > address space in question does provide memory semantics does make > > > > sense. That should defenitely be documented in the ACPI standard > > > > though. > > > > > > Mapping SystemMemory Opregions as "memory" does not make sense > > > at all to me. Still, that's what Linux ACPICA code does (*if* > > > that's what acpi_os_map_memory() is supposed to mean). > > > > > > https://lore.kernel.org/linux-acpi/20210916160827.GA4525@lpieralisi > > > > It doesn't need to do that, though, if there are good enough arguments > > to change the current behavior (and the argument here is that it may > > be an MMIO region, so mapping it as memory doesn't really work, but it > > also may be a region in memory - there is no rule in the spec by which > > SystemMemory Opregions cannot be "memory" AFAICS) and if that change > > doesn't introduce regressions in the installed base. > > > > > Where do we go from here, to be defined, we still have a bug > > > to fix after the revert is applied. > > > > > > drivers/acpi/sysfs.c > > > > > > maps BERT error regions with acpi_os_map_memory(). > > > > That mechanism is basically used for exporting ACPI tables to user > > space and they are known to reside in memory. Whether or not BERT > > regions should be mapped in the same way is a good question. > > It is not inconceivable that BERT regions actually live in memory of > the BMC that is exposed over a bus that doesn't implement memory > semantics is it? No, it isn't, which is why I think that mapping them as RAM may not be a good idea in general. At the same time, mapping the ACPI tables like the DSDT etc. as RAM is always valid. 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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 523E8C433EF for ; Thu, 23 Sep 2021 12:57:32 +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 0E0F061019 for ; Thu, 23 Sep 2021 12:57:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0E0F061019 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=pX8KQ1DnPJnFxzozQ1vgyx747SlYE3fzzfj98GlZwg8=; b=Ym2PkT+Jkh6tkL P/YqphJf73+GgT0r+dbxhoDM5VvLgLpmX1O54rP0yVzEk+UX+Bhh1a0qVQSa6Run6n8nqRjGN13Qb KqbU9h+oEpbar0nukjU3ZAQtyUPX1I6G2L9eFWmH9re2FePfg13XbutgVQ/R6C1Az4BA/e1JTBPhm JNz5S6ZwOtg8bg0Lyhk1IvKmPEwJVmv652u/iKCNPGfZheRQEyTVHjCjI8a+03v8yNY03tmVi2Mp+ sbMQwg48MfU/ah2YLgcQ+RyFuLvcYDSJ0aUiEEqw7yozVaf4vwKJjWNE6u5yP0EmwSJB/yT9Iwg1U 2gSVwZRgK7s5SS1o0OCg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mTOFn-00BUBN-O7; Thu, 23 Sep 2021 12:55:07 +0000 Received: from mail-ot1-f43.google.com ([209.85.210.43]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mTOFk-00BUB1-65 for linux-arm-kernel@lists.infradead.org; Thu, 23 Sep 2021 12:55:06 +0000 Received: by mail-ot1-f43.google.com with SMTP id g62-20020a9d2dc4000000b0054752cfbc59so2654212otb.1 for ; Thu, 23 Sep 2021 05:55:03 -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=9cnE91Z/Nvkblt8KBxlBOz53Y6ULkVoI6AYMgns74AQ=; b=sbM2ndlQALPw7tyYZFtUJllGKlK2WTD9i5h8JiwHixkhl7qb8PrBGW6h1FblnGmM5q qAY8rrtnl4MtdbS75FPUvbQa6e6cEpsRKSDjhPLIucknP7oQhTouKSy3UPSE/lq98Bex cWptwGnud8bjjJza/MDIvf9dE+FE5o/94xk+rrArEYpQgRNCZRNS52ERz5okHPo+fcVF ay6rtYmz6H6O1TF1QqUfbdFg+KaYIHov5M9pUBumLfXmUublUH0ttEZ0owK3VtR0sWWD boukftmorWS/rECUzn3e6irQcHO5cEUkImd4YSDS+EIIL8dZmnuv8QIgRzIik39ztr+7 65lA== X-Gm-Message-State: AOAM530rrQLkDRNl6/7TFCE14Oz7uQv1BUoD9psFDe/o0Zernz0Bm9VX mIpWF9ErDT+8BSRuK8AacyI812Dd026qagVPpdsX4Nvh X-Google-Smtp-Source: ABdhPJy+DM/7fT9mdBRiBQ1UqkGSyZLL8dWzJQl/kV0NQnaajz48gdaoaHkrbTe8M5Xt/wAgkOMXK6u6ADeQd59vYFI= X-Received: by 2002:a05:6830:165a:: with SMTP id h26mr4285920otr.301.1632401703209; Thu, 23 Sep 2021 05:55:03 -0700 (PDT) MIME-Version: 1.0 References: <20210910122820.26886-1-justin.he@arm.com> <20210910143223.6705-1-justin.he@arm.com> <20210922163336.GA24633@lpieralisi> <56147a0b8b9fba46@bloch.sibelius.xs4all.nl> <20210923094031.GA6454@lpieralisi> <56147c6e73afe9f6@bloch.sibelius.xs4all.nl> In-Reply-To: <56147c6e73afe9f6@bloch.sibelius.xs4all.nl> From: "Rafael J. Wysocki" Date: Thu, 23 Sep 2021 14:54:52 +0200 Message-ID: Subject: Re: [PATCH v2] Revert "ACPI: Add memory semantics to acpi_os_map_memory()" To: Mark Kettenis Cc: "Rafael J. Wysocki" , Lorenzo Pieralisi , Jia He , Harb Abdulhamid , Will Deacon , Len Brown , Robert Moore , Erik Kaneda , Linux ARM , Linux Kernel Mailing List , ACPI Devel Maling List , "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" , Ard Biesheuvel , Hanjun Guo , Catalin Marinas , Rafael Wysocki X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210923_055504_294921_C9A58EF8 X-CRM114-Status: GOOD ( 48.99 ) 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 Thu, Sep 23, 2021 at 2:26 PM Mark Kettenis wrote: > > > From: "Rafael J. Wysocki" > > Date: Thu, 23 Sep 2021 13:05:05 +0200 > > > > On Thu, Sep 23, 2021 at 11:40 AM Lorenzo Pieralisi > > wrote: > > > > > > On Thu, Sep 23, 2021 at 01:09:58AM +0200, Mark Kettenis wrote: > > > > > Date: Wed, 22 Sep 2021 17:33:36 +0100 > > > > > From: Lorenzo Pieralisi > > > > > > > > > > On Fri, Sep 10, 2021 at 10:32:23PM +0800, 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. > > > > > > > > > > > > Fixes: 437b38c51162 ("ACPI: Add memory semantics to acpi_os_map_memory()") > > > > > > Cc: Lorenzo Pieralisi > > > > > > Cc: Ard Biesheuvel > > > > > > Cc: Hanjun Guo > > > > > > Cc: Catalin Marinas > > > > > > Cc: Rafael J. Wysocki > > > > > > Cc: Harb Abdulhamid > > > > > > > > > > > > Signed-off-by: Jia He > > > > > > > > > > Rewrote the commit log, please take the patch below and repost > > > > > it as a v3. > > > > > > > > > > It would still be great if Ampere can help us understand why > > > > > the NormalNC attributes trigger a sync abort on the opregion > > > > > before merging it. > > > > > > > > To be honest, I don't think you really need an explanation from Ampere > > > > here. Mapping a part of the address space that doesn't provide memory > > > > semantics with NormalNC attributes is wrong and triggering a sync > > > > abort in that case is way better than silently ignoring the access. > > > > > > That's understood and that's what I explained in the revert commit > > > log, no question about it. > > > > > > I was just asking to confirm if that's what's actually happening. > > > > > > > Putting my OpenBSD hat on (where we have our own ACPI OSPM > > > > implementation) I must say that we always interpreted SystemMemory as > > > > memory mapped IO and I think that is a logical choice as SystemIO is > > > > used for (non-memory mapped) IO. And I'd say that the ACPI OSPM code > > > > should make sure that it uses properly aligned access to any Field > > > > object that doesn't use AnyAcc as its access type. Even on x86! And > > > > I'd say that AML that uses AnyAcc fields for SystemMemory OpRegions on > > > > arm64 is buggy. > > > > > > > > But maybe relaxing this when the EFI memory map indicates that the > > > > address space in question does provide memory semantics does make > > > > sense. That should defenitely be documented in the ACPI standard > > > > though. > > > > > > Mapping SystemMemory Opregions as "memory" does not make sense > > > at all to me. Still, that's what Linux ACPICA code does (*if* > > > that's what acpi_os_map_memory() is supposed to mean). > > > > > > https://lore.kernel.org/linux-acpi/20210916160827.GA4525@lpieralisi > > > > It doesn't need to do that, though, if there are good enough arguments > > to change the current behavior (and the argument here is that it may > > be an MMIO region, so mapping it as memory doesn't really work, but it > > also may be a region in memory - there is no rule in the spec by which > > SystemMemory Opregions cannot be "memory" AFAICS) and if that change > > doesn't introduce regressions in the installed base. > > > > > Where do we go from here, to be defined, we still have a bug > > > to fix after the revert is applied. > > > > > > drivers/acpi/sysfs.c > > > > > > maps BERT error regions with acpi_os_map_memory(). > > > > That mechanism is basically used for exporting ACPI tables to user > > space and they are known to reside in memory. Whether or not BERT > > regions should be mapped in the same way is a good question. > > It is not inconceivable that BERT regions actually live in memory of > the BMC that is exposed over a bus that doesn't implement memory > semantics is it? No, it isn't, which is why I think that mapping them as RAM may not be a good idea in general. At the same time, mapping the ACPI tables like the DSDT etc. as RAM is always valid. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============6847670900284032706==" MIME-Version: 1.0 From: Rafael J. Wysocki Subject: [Devel] Re: [PATCH v2] Revert "ACPI: Add memory semantics to acpi_os_map_memory()" Date: Thu, 23 Sep 2021 14:54:52 +0200 Message-ID: In-Reply-To: 56147c6e73afe9f6@bloch.sibelius.xs4all.nl List-ID: To: devel@acpica.org --===============6847670900284032706== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Thu, Sep 23, 2021 at 2:26 PM Mark Kettenis w= rote: > > > From: "Rafael J. Wysocki" > > Date: Thu, 23 Sep 2021 13:05:05 +0200 > > > > On Thu, Sep 23, 2021 at 11:40 AM Lorenzo Pieralisi > > wrote: > > > > > > On Thu, Sep 23, 2021 at 01:09:58AM +0200, Mark Kettenis wrote: > > > > > Date: Wed, 22 Sep 2021 17:33:36 +0100 > > > > > From: Lorenzo Pieralisi > > > > > > > > > > On Fri, Sep 10, 2021 at 10:32:23PM +0800, 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 0.1= 4 02/22/2019 > > > > > > pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=3D= --) > > > > > > [...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. > > > > > > > > > > > > Fixes: 437b38c51162 ("ACPI: Add memory semantics to acpi_os_map= _memory()") > > > > > > Cc: Lorenzo Pieralisi > > > > > > Cc: Ard Biesheuvel > > > > > > Cc: Hanjun Guo > > > > > > Cc: Catalin Marinas > > > > > > Cc: Rafael J. Wysocki > > > > > > Cc: Harb Abdulhamid > > > > > > > > > > > > Signed-off-by: Jia He > > > > > > > > > > Rewrote the commit log, please take the patch below and repost > > > > > it as a v3. > > > > > > > > > > It would still be great if Ampere can help us understand why > > > > > the NormalNC attributes trigger a sync abort on the opregion > > > > > before merging it. > > > > > > > > To be honest, I don't think you really need an explanation from Amp= ere > > > > here. Mapping a part of the address space that doesn't provide mem= ory > > > > semantics with NormalNC attributes is wrong and triggering a sync > > > > abort in that case is way better than silently ignoring the access. > > > > > > That's understood and that's what I explained in the revert commit > > > log, no question about it. > > > > > > I was just asking to confirm if that's what's actually happening. > > > > > > > Putting my OpenBSD hat on (where we have our own ACPI OSPM > > > > implementation) I must say that we always interpreted SystemMemory = as > > > > memory mapped IO and I think that is a logical choice as SystemIO is > > > > used for (non-memory mapped) IO. And I'd say that the ACPI OSPM co= de > > > > should make sure that it uses properly aligned access to any Field > > > > object that doesn't use AnyAcc as its access type. Even on x86! A= nd > > > > I'd say that AML that uses AnyAcc fields for SystemMemory OpRegions= on > > > > arm64 is buggy. > > > > > > > > But maybe relaxing this when the EFI memory map indicates that the > > > > address space in question does provide memory semantics does make > > > > sense. That should defenitely be documented in the ACPI standard > > > > though. > > > > > > Mapping SystemMemory Opregions as "memory" does not make sense > > > at all to me. Still, that's what Linux ACPICA code does (*if* > > > that's what acpi_os_map_memory() is supposed to mean). > > > > > > https://lore.kernel.org/linux-acpi/20210916160827.GA4525(a)lpieralisi > > > > It doesn't need to do that, though, if there are good enough arguments > > to change the current behavior (and the argument here is that it may > > be an MMIO region, so mapping it as memory doesn't really work, but it > > also may be a region in memory - there is no rule in the spec by which > > SystemMemory Opregions cannot be "memory" AFAICS) and if that change > > doesn't introduce regressions in the installed base. > > > > > Where do we go from here, to be defined, we still have a bug > > > to fix after the revert is applied. > > > > > > drivers/acpi/sysfs.c > > > > > > maps BERT error regions with acpi_os_map_memory(). > > > > That mechanism is basically used for exporting ACPI tables to user > > space and they are known to reside in memory. Whether or not BERT > > regions should be mapped in the same way is a good question. > > It is not inconceivable that BERT regions actually live in memory of > the BMC that is exposed over a bus that doesn't implement memory > semantics is it? No, it isn't, which is why I think that mapping them as RAM may not be a good idea in general. At the same time, mapping the ACPI tables like the DSDT etc. as RAM is always valid. --===============6847670900284032706==--