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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 94B25C433FE for ; Fri, 21 Oct 2022 13:54:06 +0000 (UTC) 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:References:Cc:To:From: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=yv1oCFwOcA+7/MBQG65fjNBDEwJt4V4FpRzzY2QPh4I=; b=HZtpqKW7Oopzzo tQDEm9wT2NBoEu/cOQyXm955dzuFJp2M2w7wCTDb9RG8o1eQyrBz0i2arfLYcKQwNYqn/9miZvdZj VWBDjQ0r1Mf/QIHxwKDuP0pd4rKvY9sCcXnL9qY9WW6eFq9+TQnl9YAweq86F+pyzqEaYPVa4H3lM 0NESPcDKtLpU+nsKCG22OqCZmGBPc6wyAQhdjc1Srars1dfHlvmTULw2z8++GjzkQfhwyZuW5vhnX Fb+Sbdv3yw9Ar4ppcnacq4TI0d3F4SycnPj73vU1R9UwVUEJXvzqxebmtuJ4j2R4cvsNnVUoc2IHV KDhnt8Y3qltNuCjouadQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1olsTH-008Iw2-Fg; Fri, 21 Oct 2022 13:53:59 +0000 Received: from fanzine.igalia.com ([178.60.130.6] helo=fanzine2.igalia.com) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1okQgn-00CQzn-4k; Mon, 17 Oct 2022 14:01:58 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:References: Cc:To:From:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=ccNFH8oqnQs0DDOD5l2+8QhyjoRsBFYdAqg8ytBphUI=; b=oE8vLPxK9isTmTE8r4fCiWVZlM TSNd9Ttokv0OcU3WpogrEnpqMIWo+btpSQYm68i5MqeSBOMeZ7f2gncGNjZ0dDeAMMZ28t74kFs1u Lq5hpJIPPTUyIrSMVtIjdRbEyw/8fYk3tk3ER+LXa3TdMdN3C9+CkioZGRdlG2g6y4SGAi1fqeM8n RIy3TKQNMSvTdf2SqdIJiGP0NHPGnZRm6HGEP6QUMwkXhHHu7P+hKyzOlHtoa074vR1nG6aF6zMYV 9090sDEKredFKyak5RKp67fKgmkBez06Tbvnnz7dhNsszQvdw5sfkzkqlkeQKYVpW/CjJRlWMBncz Dp4bVR5g==; Received: from [179.113.159.85] (helo=[192.168.1.60]) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_128_GCM:128) (Exim) id 1okQg7-000Nwb-57; Mon, 17 Oct 2022 16:01:15 +0200 Message-ID: <8e30b99e-70ed-7d5a-ea1f-3b0fadb644bc@igalia.com> Date: Mon, 17 Oct 2022 11:00:46 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.2 Subject: Re: [PATCH V3 01/11] ARM: Disable FIQs (but not IRQs) on CPUs shutdown paths Content-Language: en-US From: "Guilherme G. Piccoli" To: Russell King , Marc Zyngier , linux-arm-kernel@lists.infradead.org, will@kernel.org, Mark Rutland , arnd@arndb.de, Catalin Marinas Cc: kexec@lists.infradead.org, pmladek@suse.com, bhe@redhat.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org, netdev@vger.kernel.org, x86@kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, halves@canonical.com, fabiomirmar@gmail.com, alejandro.j.jimenez@oracle.com, andriy.shevchenko@linux.intel.com, bp@alien8.de, corbet@lwn.net, d.hatayama@jp.fujitsu.com, dave.hansen@linux.intel.com, dyoung@redhat.com, feng.tang@intel.com, gregkh@linuxfoundation.org, mikelley@microsoft.com, hidehiro.kawai.ez@hitachi.com, jgross@suse.com, john.ogness@linutronix.de, keescook@chromium.org, luto@kernel.org, mhiramat@kernel.org, mingo@redhat.com, paulmck@kernel.org, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, stern@rowland.harvard.edu, tglx@linutronix.de, vgoyal@redhat.com, vkuznets@redhat.com, xuqiang36@huawei.com References: <20220819221731.480795-1-gpiccoli@igalia.com> <20220819221731.480795-2-gpiccoli@igalia.com> In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221017_070157_210842_CBE72922 X-CRM114-Status: GOOD ( 11.21 ) X-Mailman-Approved-At: Fri, 21 Oct 2022 06:53:58 -0700 X-BeenThere: kexec@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: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 18/09/2022 10:58, Guilherme G. Piccoli wrote: > On 19/08/2022 19:17, Guilherme G. Piccoli wrote: >> Currently the regular CPU shutdown path for ARM disables IRQs/FIQs >> in the secondary CPUs - smp_send_stop() calls ipi_cpu_stop(), which >> is responsible for that. IRQs are architecturally masked when we >> take an interrupt, but FIQs are high priority than IRQs, hence they >> aren't masked. With that said, it makes sense to disable FIQs here, >> but there's no need for (re-)disabling IRQs. >> >> More than that: there is an alternative path for disabling CPUs, >> in the form of function crash_smp_send_stop(), which is used for >> kexec/panic path. This function relies on a SMP call that also >> triggers a busy-wait loop [at machine_crash_nonpanic_core()], but >> without disabling FIQs. This might lead to odd scenarios, like >> early interrupts in the boot of kexec'd kernel or even interrupts >> in secondary "disabled" CPUs while the main one still works in the >> panic path and assumes all secondary CPUs are (really!) off. >> >> So, let's disable FIQs in both paths and *not* disable IRQs a second >> time, since they are already masked in both paths by the architecture. >> This way, we keep both CPU quiesce paths consistent and safe. >> >> Cc: Marc Zyngier >> Cc: Michael Kelley >> Cc: Russell King >> Signed-off-by: Guilherme G. Piccoli >> Monthly ping - let me know if there's something I should improve in order this fix is considered! Thanks, Guilherme _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec