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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 11372C388F7 for ; Fri, 13 Nov 2020 09:40:16 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 8EEE222263 for ; Fri, 13 Nov 2020 09:40:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="G0WRqRMN"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="sehyT5t2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8EEE222263 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=bWS+LCx4AxyS91mi7qk5iUX8MjBMxwnG06p3sBQm9Dw=; b=G0WRqRMNoxXfbQz5yaT/Pv+Dv SOVwExD9kKzEVzK1ISHWlAqkrehj+f2u4hsYWNaOJdEyIcPOGNF1mvahqWnAkwswRTgLu5qWo+ZS4 i0CPcIQOryUmqGl+yfq6RHqQBhGvBE+9zAQVgaS5rRB3h2ekyF/d8sLC5CAjYZ1nieXpKq4/F+lzZ bxXmDCMNWI6meMwp5PV+KXEDylz2bTipCXnGbZZClA/54qNLBmIjavHQVNUya2uSSEGmu7sh9AJtA qFsUmEVgefm9NT90VzqeaBXJeOQ6Go7O+e83AmmxnxnNER6XnQWKVy2eWOVmocsU20Wc3zhDBtLrl aGCjkRyJA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kdVYP-00037C-7Q; Fri, 13 Nov 2020 09:39:37 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kdVXB-0002VB-PX for linux-arm-kernel@lists.infradead.org; Fri, 13 Nov 2020 09:38:24 +0000 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 915D122267; Fri, 13 Nov 2020 09:38:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605260300; bh=TS3RQbahQ1aCWxlNBrLZsbJ5uEZyLzGE0YxtwgY+69U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sehyT5t29MrChZlNZalMKfhNWEmG8CalXXxHhNb4OeEvpSMZcxf2aJDDCrPNj093B bIU7FKMMHbvpyNDYmKBDjVxndotDz5017Lt1AL/DZcZRbBsoiAR8ZpJhUijb74ix1q WAvIpv0UGk9yyB3UPPBZmkZVWjNexEP+5J5bh0/8= From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 12/14] arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched system Date: Fri, 13 Nov 2020 09:37:17 +0000 Message-Id: <20201113093720.21106-13-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201113093720.21106-1-will@kernel.org> References: <20201113093720.21106-1-will@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201113_043822_021762_87586256 X-CRM114-Status: GOOD ( 17.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Marc Zyngier , kernel-team@android.com, Vincent Guittot , Juri Lelli , Quentin Perret , Peter Zijlstra , Catalin Marinas , Johannes Weiner , linux-kernel@vger.kernel.org, Qais Yousef , Suren Baghdasaryan , Ingo Molnar , Li Zefan , Greg Kroah-Hartman , Tejun Heo , Will Deacon , Morten Rasmussen 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 If we want to support 32-bit applications, then when we identify a CPU with mismatched 32-bit EL0 support we must ensure that we will always have an active 32-bit CPU available to us from then on. This is important for the scheduler, because is_cpu_allowed() will be constrained to 32-bit CPUs for compat tasks and forced migration due to a hotplug event will hang if no 32-bit CPUs are available. On detecting a mismatch, prevent offlining of either the mismatching CPU if it is 32-bit capable, or find the first active 32-bit capable CPU otherwise. Signed-off-by: Will Deacon --- arch/arm64/kernel/cpufeature.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index dfded018af44..853f3ac876a3 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1237,6 +1237,8 @@ has_cpuid_feature(const struct arm64_cpu_capabilities *entry, int scope) static int enable_mismatched_32bit_el0(unsigned int cpu) { + static int lucky_winner = -1; + struct cpuinfo_arm64 *info = &per_cpu(cpu_data, cpu); bool cpu_32bit = id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0); @@ -1245,6 +1247,22 @@ static int enable_mismatched_32bit_el0(unsigned int cpu) static_branch_enable_cpuslocked(&arm64_mismatched_32bit_el0); } + if (cpumask_test_cpu(0, cpu_32bit_el0_mask) == cpu_32bit) + return 0; + + if (lucky_winner >= 0) + return 0; + + /* + * We've detected a mismatch. We need to keep one of our CPUs with + * 32-bit EL0 online so that is_cpu_allowed() doesn't end up rejecting + * every CPU in the system for a 32-bit task. + */ + lucky_winner = cpu_32bit ? cpu : cpumask_any_and(cpu_32bit_el0_mask, + cpu_active_mask); + get_cpu_device(lucky_winner)->offline_disabled = true; + pr_info("Asymmetric 32-bit EL0 support detected on CPU %u; CPU hot-unplug disabled on CPU %u\n", + cpu, lucky_winner); return 0; } -- 2.29.2.299.gdc1121823c-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel