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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58ACDC4167B for ; Thu, 30 Nov 2023 17:40:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346548AbjK3Rjz (ORCPT ); Thu, 30 Nov 2023 12:39:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235211AbjK3Rjy (ORCPT ); Thu, 30 Nov 2023 12:39:54 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4B96210FC; Thu, 30 Nov 2023 09:40:00 -0800 (PST) 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 B54A7143D; Thu, 30 Nov 2023 09:40:46 -0800 (PST) Received: from [10.1.197.60] (eglon.cambridge.arm.com [10.1.197.60]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 185523F6C4; Thu, 30 Nov 2023 09:39:54 -0800 (PST) Message-ID: Date: Thu, 30 Nov 2023 17:39:49 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v9 1/2] ACPI: APEI: set memory failure flags as MF_ACTION_REQUIRED on synchronous events Content-Language: en-GB To: Shuai Xue , rafael@kernel.org, wangkefeng.wang@huawei.com, tanxiaofei@huawei.com, mawupeng1@huawei.com, tony.luck@intel.com, linmiaohe@huawei.com, naoya.horiguchi@nec.com, gregkh@linuxfoundation.org, will@kernel.org, jarkko@kernel.org Cc: linux-acpi@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, linux-edac@vger.kernel.org, acpica-devel@lists.linuxfoundation.org, stable@vger.kernel.org, x86@kernel.org, justin.he@arm.com, ardb@kernel.org, ying.huang@intel.com, ashish.kalra@amd.com, baolin.wang@linux.alibaba.com, bp@alien8.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, lenb@kernel.org, hpa@zytor.com, robert.moore@intel.com, lvying6@huawei.com, xiexiuqi@huawei.com, zhuo.song@linux.alibaba.com References: <20221027042445.60108-1-xueshuai@linux.alibaba.com> <20231007072818.58951-2-xueshuai@linux.alibaba.com> From: James Morse In-Reply-To: <20231007072818.58951-2-xueshuai@linux.alibaba.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Shuai, On 07/10/2023 08:28, Shuai Xue wrote: > There are two major types of uncorrected recoverable (UCR) errors : Is UCR a well known x86 acronym? It's best to just spell this out each time, there is enough jargon in this area already. > > - Action Required (AR): The error is detected and the processor already > consumes the memory. OS requires to take action (for example, offline > failure page/kill failure thread) to recover this uncorrectable error. > > - Action Optional (AO): The error is detected out of processor execution > context. Some data in the memory are corrupted. But the data have not > been consumed. OS is optional to take action to recover this > uncorrectable error. As elsewhere, please don't think of errors as 'action required', this is how things get reported to user-space. Action-required for one thread may be action-optional for another that has the same page mapped - its really not a property of the error. It would be better to describe this as synchronous and asynchronous, or in-band and out-of-band. > The essential difference between AR and AO errors is that AR is a > synchronous event, while AO is an asynchronous event. The hardware will > signal a synchronous exception (Machine Check Exception on X86 and > Synchronous External Abort on Arm64) when an error is detected and the > memory access has been architecturally executed. > When APEI firmware first is enabled, a platform may describe one error > source for the handling of synchronous errors (e.g. MCE or SEA notification > ), or for handling asynchronous errors (e.g. SCI or External Interrupt > notification). In other words, we can distinguish synchronous errors by > APEI notification. For AR errors, kernel will kill current process > accessing the poisoned page by sending SIGBUS with BUS_MCEERR_AR. In > addition, for AO errors, kernel will notify the process who owns the > poisoned page by sending SIGBUS with BUS_MCEERR_AO in early kill mode. > However, the GHES driver always sets mf_flags to 0 so that all UCR errors > are handled as AO errors in memory failure. To make this easier to read: UCR and AR -> synchronous AO -> asynchronous > To this end, set memory failure flags as MF_ACTION_REQUIRED on synchronous > events. > Fixes: ba61ca4aab47 ("ACPI, APEI, GHES: Add hardware memory error recovery support")' Erm, this predates arm64 support, and what you have here doesn't change the behaviour on x86. You can blame 7f17b4a121d0d50 ("ACPI: APEI: Kick the memory_failure() queue for synchronous errors"), which should have covered this. > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c > index ef59d6ea16da..88178aa6222d 100644 > --- a/drivers/acpi/apei/ghes.c > +++ b/drivers/acpi/apei/ghes.c > @@ -101,6 +101,20 @@ static inline bool is_hest_type_generic_v2(struct ghes *ghes) > return ghes->generic->header.type == ACPI_HEST_TYPE_GENERIC_ERROR_V2; > } > > +/* > + * A platform may describe one error source for the handling of synchronous > + * errors (e.g. MCE or SEA), or for handling asynchronous errors (e.g. SCI > + * or External Interrupt). On x86, the HEST notifications are always > + * asynchronous, so only SEA on ARM is delivered as a synchronous > + * notification. > + */ > +static inline bool is_hest_sync_notify(struct ghes *ghes) > +{ > + u8 notify_type = ghes->generic->notify.type; > + > + return notify_type == ACPI_HEST_NOTIFY_SEA; > +} and as you had in earlier versions, sometimes SDEI. SDEI can report by synchronous and asynchronous errors, I wouldn't too surprised if the hardware NMI can be used for the same. It would be good to chase up having a hint of this in the CPER records and pass that in here as a hint. Unfortunately, its not safe to assume either way for SDEI. Reviewed-by: James Morse Thanks, James