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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 CD825C433E0 for ; Fri, 12 Feb 2021 12:03:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A290F64E01 for ; Fri, 12 Feb 2021 12:03:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230296AbhBLMDf (ORCPT ); Fri, 12 Feb 2021 07:03:35 -0500 Received: from foss.arm.com ([217.140.110.172]:35890 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229992AbhBLMBI (ORCPT ); Fri, 12 Feb 2021 07:01:08 -0500 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 48B8A113E; Fri, 12 Feb 2021 04:00:22 -0800 (PST) Received: from e121166-lin.cambridge.arm.com (e121166-lin.cambridge.arm.com [10.1.196.255]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 80EA73F719; Fri, 12 Feb 2021 04:00:20 -0800 (PST) Date: Fri, 12 Feb 2021 12:00:15 +0000 From: Lorenzo Pieralisi To: Vincenzo Frascino Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Andrew Morton , Catalin Marinas , Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Andrey Konovalov Subject: Re: [PATCH v13 6/7] arm64: mte: Report async tag faults before suspend Message-ID: <20210212120015.GA18281@e121166-lin.cambridge.arm.com> References: <20210211153353.29094-1-vincenzo.frascino@arm.com> <20210211153353.29094-7-vincenzo.frascino@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210211153353.29094-7-vincenzo.frascino@arm.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 11, 2021 at 03:33:52PM +0000, Vincenzo Frascino wrote: > When MTE async mode is enabled TFSR_EL1 contains the accumulative > asynchronous tag check faults for EL1 and EL0. > > During the suspend/resume operations the firmware might perform some > operations that could change the state of the register resulting in > a spurious tag check fault report. > > Report asynchronous tag faults before suspend and clear the TFSR_EL1 > register after resume to prevent this to happen. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Lorenzo Pieralisi > Signed-off-by: Vincenzo Frascino > --- > arch/arm64/include/asm/mte.h | 4 ++++ > arch/arm64/kernel/mte.c | 20 ++++++++++++++++++++ > arch/arm64/kernel/suspend.c | 3 +++ > 3 files changed, 27 insertions(+) > > diff --git a/arch/arm64/include/asm/mte.h b/arch/arm64/include/asm/mte.h > index 43169b978cd3..33e88a470357 100644 > --- a/arch/arm64/include/asm/mte.h > +++ b/arch/arm64/include/asm/mte.h > @@ -41,6 +41,7 @@ void mte_sync_tags(pte_t *ptep, pte_t pte); > void mte_copy_page_tags(void *kto, const void *kfrom); > void flush_mte_state(void); > void mte_thread_switch(struct task_struct *next); > +void mte_suspend_enter(void); > void mte_suspend_exit(void); > long set_mte_ctrl(struct task_struct *task, unsigned long arg); > long get_mte_ctrl(struct task_struct *task); > @@ -66,6 +67,9 @@ static inline void flush_mte_state(void) > static inline void mte_thread_switch(struct task_struct *next) > { > } > +static inline void mte_suspend_enter(void) > +{ > +} > static inline void mte_suspend_exit(void) > { > } > diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c > index f5aa5bea6dfe..de905102245a 100644 > --- a/arch/arm64/kernel/mte.c > +++ b/arch/arm64/kernel/mte.c > @@ -258,12 +258,32 @@ void mte_thread_switch(struct task_struct *next) > mte_check_tfsr_el1(); > } > > +void mte_suspend_enter(void) > +{ > + if (!system_supports_mte()) > + return; > + > + /* > + * The barriers are required to guarantee that the indirect writes > + * to TFSR_EL1 are synchronized before we report the state. > + */ > + dsb(nsh); > + isb(); > + > + /* Report SYS_TFSR_EL1 before suspend entry */ > + mte_check_tfsr_el1(); > +} > + > void mte_suspend_exit(void) > { > if (!system_supports_mte()) > return; > > update_gcr_el1_excl(gcr_kernel_excl); > + > + /* Clear SYS_TFSR_EL1 after suspend exit */ > + write_sysreg_s(0, SYS_TFSR_EL1); AFAICS it is not needed, it is done already in __cpu_setup() (that is called by cpu_resume on return from cpu_suspend() from firmware). However, I have a question. We are relying on context switch to set sctlr_el1_tfc0 right ? If that's the case, till the thread resuming from low power switches context we are running with SCTLR_EL1_TCF0 not reflecting the actual value. Just making sure that I understand it correctly, I need to check the resume from suspend-to-RAM path, it is something that came up with perf save/restore already in the past. Lorenzo > + > } > > long set_mte_ctrl(struct task_struct *task, unsigned long arg) > diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c > index a67b37a7a47e..25a02926ad88 100644 > --- a/arch/arm64/kernel/suspend.c > +++ b/arch/arm64/kernel/suspend.c > @@ -91,6 +91,9 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) > unsigned long flags; > struct sleep_stack_data state; > > + /* Report any MTE async fault before going to suspend */ > + mte_suspend_enter(); > + > /* > * From this point debug exceptions are disabled to prevent > * updates to mdscr register (saved and restored along with > -- > 2.30.0 >