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 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 2C310C44502 for ; Wed, 21 Jan 2026 10:15:18 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.1209571.1521538 (Exim 4.92) (envelope-from ) id 1viVEu-0000qm-PZ; Wed, 21 Jan 2026 10:15:04 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1209571.1521538; Wed, 21 Jan 2026 10:15:04 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1viVEu-0000qf-MD; Wed, 21 Jan 2026 10:15:04 +0000 Received: by outflank-mailman (input) for mailman id 1209571; Wed, 21 Jan 2026 10:15:03 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1viVEt-0000qS-Di for xen-devel@lists.xenproject.org; Wed, 21 Jan 2026 10:15:03 +0000 Received: from SN4PR0501CU005.outbound.protection.outlook.com (mail-southcentralusazlp170110003.outbound.protection.outlook.com [2a01:111:f403:c10d::3]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 0b92b4d0-f6b2-11f0-b15e-2bf370ae4941; Wed, 21 Jan 2026 11:15:01 +0100 (CET) Received: from MN2PR10CA0034.namprd10.prod.outlook.com (2603:10b6:208:120::47) by MW3PR12MB4476.namprd12.prod.outlook.com (2603:10b6:303:2d::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.10; Wed, 21 Jan 2026 10:14:57 +0000 Received: from BL6PEPF00020E62.namprd04.prod.outlook.com (2603:10b6:208:120:cafe::82) by MN2PR10CA0034.outlook.office365.com (2603:10b6:208:120::47) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.20.9542.9 via Frontend Transport; Wed, 21 Jan 2026 10:14:56 +0000 Received: from satlexmb07.amd.com (165.204.84.17) by BL6PEPF00020E62.mail.protection.outlook.com (10.167.249.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.4 via Frontend Transport; Wed, 21 Jan 2026 10:14:56 +0000 Received: from localhost (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Wed, 21 Jan 2026 04:14:55 -0600 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: 0b92b4d0-f6b2-11f0-b15e-2bf370ae4941 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=lrDogGQnxmp2zTt5CQh+Yl/NCjXmReTCfsBaVtvZ88fh7Gra9GS0FotXyxEkRJsFGHGfleMv7qBfHvDYvraZlDkP3k/foSYPYiBgMj+3pSNQONwwPYY3y0XPQGkQNRJdJ3tOU/tSa/L7oztA/Pb3TOfWF8tlivyA04dqnQin9RTrdI8+C1wCz4scINLw27PSwaHjDFlRQnqJPJFruvQkLaxUCu9GuzV70aj3ULOyJyCu0+YXUJpB7t7lHXHOaKjp+6hGR0d+YdzR8eDuM+Ab21ZhyJTlrA+wH3q+ZwZfRge4qP/U7GVckkaH8ij90WJuKG3DY2TT7IuJtqWtZXZSoA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=kb/tGiyo3qWKeaMR0COArIKTzjNddp3s/jztw8KHiG4=; b=sX6RjPHc72jxNXPXLUbBCGdsVptYihoDucUCS6jdnvUcg3/gu5ws3NB8tHUtIU9CfD5zQ0dwdwpQr8AqsukG/lds0faYCsfmDt5+lrDG+byWjdOMhRY0djjV0ULI15cRBJP+9N53pIWyzMu3AkEs0C58ea82xBO66chJ340CjcjWjdoQAHmazA+IhQkYMkwfk8oTKNDDTnX0EQaztXXhc5tW9qzKpWydm5SD7L8b56PjO5rU1fqzXGHeWKIBlc9vfVYQcEMfe8yoLttYNZNVnSYne/+3q6Ri4CstrviaaT/W46XAwejbts49KonnFv2PJLRt9WFv4+Eglo84JOUGeg== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=vates.tech smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=kb/tGiyo3qWKeaMR0COArIKTzjNddp3s/jztw8KHiG4=; b=5aqNW6pVPZbx5Sa/iCqShgGb7xpnUcpm3hx++snenVdppPO6bqStzEXOiAcmw5vU/jifdOpVoTv5vHsOAw8PXFfKfFRIUJQH7/4xs4AB/Y3FqBx3fvxzMUDflI9IBOiRpAVD2AEDr5PGnKR92WgHx5Xk5Q+S+0X11WVDoTv8B20= X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" Date: Wed, 21 Jan 2026 11:14:53 +0100 Message-ID: CC: Anthony PERARD , Juergen Gross , Andrew Cooper , "Jan Beulich" , Grygorii Strashko Subject: Re: [RFC PATCH v2] x86/hvm: Allow pre-enabling x2apic mode on BSP From: Alejandro Vallejo To: Teddy Astie , X-Mailer: aerc 0.20.1 References: <0cb4d1f91212a65baf924ed0ef825d8adb4b5423.1762958551.git.teddy.astie@vates.tech> In-Reply-To: <0cb4d1f91212a65baf924ed0ef825d8adb4b5423.1762958551.git.teddy.astie@vates.tech> X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF00020E62:EE_|MW3PR12MB4476:EE_ X-MS-Office365-Filtering-Correlation-Id: 569e70f8-3c70-4186-9b90-08de58d5ed6d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|82310400026|36860700013|1800799024|7053199007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?R3VpQWRmbWtIT244SWVHWkdkRjd5dzU3WHlZQ0o3VUFQRkZIVFdjdmNKMk1i?= =?utf-8?B?NUJ0SWZSTEo3V244dHd6alk4elpaZGhhcFhXK2p0eDlSMlNrdXlEYWRZeE1F?= =?utf-8?B?MlhoMy8wTW42ZzdoKzV3RnVya01sRFk5QlpqNzZjb2dwRE14OU9yY2pIY1h3?= =?utf-8?B?TTRkVStVUFZ5dzNoNWlYeHpPL2FYRlc0Z0Z1MjQwcnlYOEtWbHBBOXR5L2xY?= =?utf-8?B?cXp4VmNGczJ5Q1NROWdOalpIWXdpcGhhQnJTNTNSUExrelU2ZVQ1ZitvNGFQ?= =?utf-8?B?eDQyakhvajZOd0tvWk1Ea3FwUW5MbmNxQXYzZFdyaVBzWWpHYm01NGxxM1ZL?= =?utf-8?B?N0xxd1dSc2FhYStUNTRCZ2E4eXkyZStBZXFHWUVCTEFVR2hoczZtQ3Q1MUdv?= =?utf-8?B?bzBGM3ZLKzFsNWVBeW42NnZaZ0IvMUNJSFpCTHBaSUZGMmtQUjYvcjF1SkJV?= =?utf-8?B?SjZaMkRRbjFEUWdUV3FCcWNvTjFtTi9LVU1OK0ZDeTlETk9SZnZkcjRab1ZH?= =?utf-8?B?dkhTc3p1WTA3OTRRbjBGWDZQMDRuaERPZDlJRHhoYWhZTHhoNHJPNFdhaWlU?= =?utf-8?B?b29PRFNwOW9YYjRZOG13dlZIOTI0M2ZvODk3TjFYSmZIMDEyWDg5Ym9BRlNI?= =?utf-8?B?V1lnY3BUNVdPdzhuWis3RWhJcUJoNXVJV1VHMEVVN2hsazVkbnRWTi9NTk0x?= =?utf-8?B?WU1VdDNSTndaelY3cXlPTm9rM2VjRGpkaFJLa1AwTHhId1NwRk9sNEtNVlFM?= =?utf-8?B?R2VXT1IyZlZ3anpwSGh4dU14V3krTU9ua3dVMHQ1VHFFcUlRcDJsWVRZWURi?= =?utf-8?B?VmEvTVpSQytsQzlLaGJVMWNPUFMxNTdSeDE1bHRUMzhnZWZ6SmliU1UvUXc1?= =?utf-8?B?MlF6eHpMMjZKWUZqOGJycmRMMEZVUHJ2UHQzVTFFZkZyS1NqNkpMZnl4QUZB?= =?utf-8?B?SmQ5SFdsOWlqNEdIdnJRZUlzK2F6anZSbjExdU9QYU5tN0s3YjM3WGdyRUhw?= =?utf-8?B?S1ZhaytZNDcxalpkaStLM1FJMHRHVEFuYkJ3VCtyUHUrV1RFb2k5RkdCV00x?= =?utf-8?B?SGxlNG9nVXVpaFV5cVFEaWp6NUwwcm43bDJHRWlKQTQvT1lzZEhPd2dvNUl6?= =?utf-8?B?ZUgzZW9KVjNjUnNqVXJnZUlGTWtQbFE3RGoxK1FRRzMrMENYaVJVWndzZmg1?= =?utf-8?B?U2N5dCtiaWFPRVVEWWNvZ0R1NjAzdEYzd042Qm1vNW1qZXo2ckx2bXhYY1RO?= =?utf-8?B?NElPUDRud29YOVdLbElXaWRlNjljS01VenIxenh1K1ByamYyb3M5Vnp1VE56?= =?utf-8?B?K3kwV0cyY0JjWDZNY2xwTXBWSWFuYjVRd2VlK1F3Z2FkWXdhQTFkdVFRREdl?= =?utf-8?B?dFRGRDNaMTJaVlpoNGVkSWlyWkxNS2o5L2FZOVNoVHd4OTE4cUZNRGtrd1k3?= =?utf-8?B?N3lmamxuemJaKysyZzNEYnl6UmxhbldSdW1hRFFPSUxLcDQzTHgyTCtEREJl?= =?utf-8?B?OXJBdTIxN29rejFhbHdZRm5rcnkyaWd3UW0yRGZUNGo2eE8vRmVxMFZvQ1dZ?= =?utf-8?B?Q254blhrdFFBV0NoK1lwdXVnR1Z3S2VyQXV0RmFyUlhjaFM5ZWZrZnQwMlQ2?= =?utf-8?B?bmZxWC9OdHlKSWdhaVdtT0JSOW4xN1RsYUQvMDVxMFVLUHdiejB3eGNvT2RT?= =?utf-8?B?SlFVNjF2OHNWMGtCcEF0U2d5WnVxeGMvU0N4TU85V01vY2p0WG1rSjZPOUg0?= =?utf-8?B?YktlRjlWaHJ1aTFLZzhhRXZiRld1WS91QmVXRTVMWnlZeGx0QjlpR1hydHRZ?= =?utf-8?B?ZDFUMyt3SnhLcU1mUzN0Z1IybmtOOFpZS2kxZUpvYW5OV3ZoYUJPcWQ3Y2t2?= =?utf-8?B?ZHQ1amU0VUZ0cDBZdUQrUVdCTlh6dTZ2Y1V2L0lhVFZhb0pGSHNGa2dPSUdY?= =?utf-8?B?TXRVOVBkSVRtTmo4REZaMzZZdVJVTHZQVEVBZjFPQXBUWXRlNnU3WkhoeE1n?= =?utf-8?B?OXN2ZCs2cmUySmpQYzlsMS9ENFRMQ0d3dTJrc2xtbzdtL2xuT0tkd3FJaWx1?= =?utf-8?B?bEhGclZiK3pFb1grOGxicTJ6QUdJY290TTN0Ry8yRG5MMW0yZDhseE13Zzlh?= =?utf-8?B?VDdGNHdGZGErMVVzZWFxSitZcDB2c1JwZkN5WnFmWEFkV3dpRlRsNFhTV3FB?= =?utf-8?B?aWgyc1hzZEtPVUVPRGlidEUzcWhHK3RhTDlSWCtZU2F1cXlVMzQ1bzdKNnhW?= =?utf-8?B?a3ptaEhKb0FwUzB5bVdBRmh5SlZBPT0=?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(82310400026)(36860700013)(1800799024)(7053199007);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Jan 2026 10:14:56.7413 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 569e70f8-3c70-4186-9b90-08de58d5ed6d X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF00020E62.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW3PR12MB4476 On Wed Nov 12, 2025 at 3:51 PM CET, Teddy Astie wrote: > Introduce a new option to start the BSP vCPU in x2APIC mode instead > of xAPIC mode. Expose this in xl through a new "x2apic_mode" option. > > Signed-off-by: Teddy Astie > --- > Cc: Andrew Cooper > Cc: Jan Beulich > Cc: Alejandro Vallejo > Cc: Grygorii Strashko > > Later on, we could consider with this option to use x2APIC ACPI > tables instead of xAPIC ones. > > There is also some room into introducing a new Kconfig option to > only support x2apic mode, which would change how the "Xen default" > would behave. > > changed in v2: > - only pre-enable instead of forcing > - use domain builder to pre-enable instead of introducing a new domain c= reation flag Hmmm. For dom0less/Hyperlaunch and CPU hotplug it'd be beneficial to actual= ly have it in the domain creation struct, I think, annoying as this might soun= d (because it's a circle back to what you had before) could we keep the misc_= flag with the different meaning of "preenable x2APIC" rather than "force"? Then on each vCPU creation (or even hotplug) we could check whether they ne= ed to be preinitialised as x2APIC or not. Otherwise hotplug needs different treat= ment. On the plus side, Hyperlaunch would merely have a new trivial binding rathe= r than an ad-hoc solution. Cheers, Alejandro