From patchwork Tue Nov 14 17:50:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Krystian Hebel X-Patchwork-Id: 13455768 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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 8CD39C4167D for ; Tue, 14 Nov 2023 17:57:58 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.633102.987717 (Exim 4.92) (envelope-from ) id 1r2xfV-0003D0-Im; Tue, 14 Nov 2023 17:57:45 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 633102.987717; Tue, 14 Nov 2023 17:57:45 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1r2xfU-00036u-QE; Tue, 14 Nov 2023 17:57:44 +0000 Received: by outflank-mailman (input) for mailman id 633102; Tue, 14 Nov 2023 17:50:46 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1r2xYk-0004wk-Me for xen-devel@lists.xenproject.org; Tue, 14 Nov 2023 17:50:46 +0000 Received: from 5.mo583.mail-out.ovh.net (5.mo583.mail-out.ovh.net [87.98.173.103]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 55eb02bf-8316-11ee-9b0e-b553b5be7939; Tue, 14 Nov 2023 18:50:45 +0100 (CET) Received: from director8.ghost.mail-out.ovh.net (unknown [10.108.4.72]) by mo583.mail-out.ovh.net (Postfix) with ESMTP id 831882530C for ; Tue, 14 Nov 2023 17:50:44 +0000 (UTC) Received: from ghost-submission-6684bf9d7b-x5j2z (unknown [10.110.115.90]) by director8.ghost.mail-out.ovh.net (Postfix) with ESMTPS id 053BA1FD62; Tue, 14 Nov 2023 17:50:43 +0000 (UTC) Received: from 3mdeb.com ([37.59.142.103]) by ghost-submission-6684bf9d7b-x5j2z with ESMTPSA id +FLBOXOzU2V/lwcATVRwWg (envelope-from ); Tue, 14 Nov 2023 17:50:43 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 55eb02bf-8316-11ee-9b0e-b553b5be7939 Authentication-Results: garm.ovh; auth=pass (GARM-103G0053f19ddfa-4a8e-402b-a711-632ec1da18cf, 1C6EC45AC3E1968723EBE40916FD99D0F8B07574) smtp.auth=krystian.hebel@3mdeb.com X-OVh-ClientIp: 213.192.77.249 From: Krystian Hebel To: xen-devel@lists.xenproject.org Cc: Krystian Hebel , Jan Beulich , Andrew Cooper , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Wei Liu Subject: [PATCH 06/10] x86/smp: call x2apic_ap_setup() earlier Date: Tue, 14 Nov 2023 18:50:08 +0100 Message-ID: <7c13554e60cc76516922992b7faf911b91f99a2a.1699981248.git.krystian.hebel@3mdeb.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: References: MIME-Version: 1.0 X-Ovh-Tracer-Id: 12930960431237409136 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvkedrudeffedgudefucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdpvefjgfevmfevgfenuceurghilhhouhhtmecuhedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvvefufffkofgjfhgggfestdekredtredttdenucfhrhhomhepmfhrhihsthhirghnucfjvggsvghluceokhhrhihsthhirghnrdhhvggsvghlseefmhguvggsrdgtohhmqeenucggtffrrghtthgvrhhnpeevtdevieehieeiveekvefhlefftdfhteefueelhfdvhedtjeegkedugfefvdekffenucfkphepuddvjedrtddrtddruddpvddufedrudelvddrjeejrddvgeelpdefjedrheelrddugedvrddutdefnecuvehluhhsthgvrhfuihiivgepgeenucfrrghrrghmpehinhgvthepuddvjedrtddrtddruddpmhgrihhlfhhrohhmpeeokhhrhihsthhirghnrdhhvggsvghlseefmhguvggsrdgtohhmqedpnhgspghrtghpthhtohepuddprhgtphhtthhopeigvghnqdguvghvvghlsehlihhsthhsrdigvghnphhrohhjvggtthdrohhrghdpoffvtefjohhsthepmhhoheekfedpmhhouggvpehsmhhtphhouhht It used to be called from smp_callin(), however BUG_ON() was invoked on multiple occasions before that. It may end up calling machine_restart() which tries to get APIC ID for CPU running this code. If BSP detected that x2APIC is enabled, get_apic_id() will try to use it for all CPUs. Enabling x2APIC on secondary CPUs earlier protects against an endless loop of #GP exceptions caused by attempts to read IA32_X2APIC_APICID MSR while x2APIC is disabled in IA32_APIC_BASE. Signed-off-by: Krystian Hebel --- xen/arch/x86/smpboot.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c index 8ae65ab1769f..a3895dafa267 100644 --- a/xen/arch/x86/smpboot.c +++ b/xen/arch/x86/smpboot.c @@ -184,7 +184,6 @@ static void smp_callin(void) * update until we finish. We are free to set up this CPU: first the APIC. */ Dprintk("CALLIN, before setup_local_APIC().\n"); - x2apic_ap_setup(); setup_local_APIC(false); /* Save our processor parameters. */ @@ -351,6 +350,14 @@ void start_secondary(void *unused) get_cpu_info()->xen_cr3 = 0; get_cpu_info()->pv_cr3 = 0; + /* + * BUG_ON() used in load_system_tables() and later code may end up calling + * machine_restart() which tries to get APIC ID for CPU running this code. + * If BSP detected that x2APIC is enabled, get_apic_id() will try to use it + * for _all_ CPUs. Enable x2APIC on secondary CPUs now so we won't end up + * with endless #GP loop. + */ + x2apic_ap_setup(); load_system_tables(); /* Full exception support from here on in. */