From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F72438B124 for ; Wed, 19 Aug 2026 05:48:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=198.175.65.18 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787118520; cv=fail; b=UIAMb3oNVXOC0isct3SoJ7izTUi2KmQM2SKOlja9s2q7QHJ3W0wX2QDcEjcZOiOf4UNWhTeZbWSTZ6skuEpfJTjqDoDLgOyq9/zAU33KE+qadOQ7Y0RDR8NbDEbBIZ/1OROtRIYrSXLkI/6/0igoOVSsSm7tk2Aon+CHLdrvszE= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787118520; c=relaxed/simple; bh=Ia73iC7BY6+BwCrbTUotH5cvTTH8WPia56DguAvKwho=; h=Date:From:To:CC:Subject:Message-ID:References:Content-Type: Content-Disposition:In-Reply-To:MIME-Version; b=uXiqRX+k9pNFMUHMC3Ld5Ra8IYR25HvgDw2vlxF1ygd7opbi/5RLncsOl1odd1pBwePxXHP+RFAs0E1PILv8ED3wJKRgr1tlLY2QFlSiEmRhede//wVYdQ7HlQnM6K1uiV5Zog/mBstG6W2cmC1m9NLelsMu41asIKRKMdRee84= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=nXV7BaZv; arc=fail smtp.client-ip=198.175.65.18 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="nXV7BaZv" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1787118519; x=1818654519; h=date:from:to:cc:subject:message-id:references: in-reply-to:mime-version; bh=Ia73iC7BY6+BwCrbTUotH5cvTTH8WPia56DguAvKwho=; b=nXV7BaZvi9BXAmQNEzedmoYZnvBzKAgYJWdBiIxW8280zLEb71gWAkfP 3wNfvgXnsbrE7XOcW5IqAOgD3Wzttl49lMRMJ8MX1NN5f4LocnSvRx+Ol q4nJgqOO9NqZPoJ/i4ygx2Rfde4lSNRJb57Tar5PsJn044eJlJ6h+xdKn T1zkQf/0TXmUb5/QOacBSuptBqqyrnDXp/+ru+fxwM1y/JPzGS3R1umA7 Yq3d94ibabXuft8O/Zn5ZHCUIMNP+Q76uFOG3ewyH92/gSqu2KuSQ3ZQh xs5ed8qWfcVG3uAwyAF2fBrM6ai3xgtvcNbXMrIQWFI3YkysCn0wXTkRR Q==; X-CSE-ConnectionGUID: r7sdM/7wTNmpcxAarc3PQg== X-CSE-MsgGUID: Uo38EFCrTGOohUxWBOu2Qw== X-IronPort-AV: E=McAfee;i="6800,10657,11879"; a="87684720" X-IronPort-AV: E=Sophos;i="6.25,231,1779174000"; d="scan'208";a="87684720" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2026 22:48:38 -0700 X-CSE-ConnectionGUID: RAaxsbXUQe+ZiaQQBlhKhw== X-CSE-MsgGUID: Y4JCnXayTZaj8qxodGsQzg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,231,1779174000"; d="scan'208";a="267403618" Received: from orsmsx903.amr.corp.intel.com ([10.22.229.25]) by fmviesa004.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Aug 2026 22:48:37 -0700 Received: from ORSMSX901.amr.corp.intel.com (10.22.229.23) by ORSMSX903.amr.corp.intel.com (10.22.229.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.45; Tue, 18 Aug 2026 22:48:36 -0700 Received: from ORSEDG901.ED.cps.intel.com (10.7.248.11) by ORSMSX901.amr.corp.intel.com (10.22.229.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.45 via Frontend Transport; Tue, 18 Aug 2026 22:48:36 -0700 Received: from SN4PR2101CU001.outbound.protection.outlook.com (40.93.195.49) by edgegateway.intel.com (134.134.137.111) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.45; Tue, 18 Aug 2026 22:48:36 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=XXPb0Ty2s7Uh26Po9U6+dTNmMqYq3AMICir5v/yMvl/AZsWaHrEeItFWb5SOK3ZRjpGtVei8xSDTAGwB9SEs3U2Epybzvd/vYmrI5OERjaHRT9dHny/JVrrf5HGKkgyQdbkK71bzTJZunmn3E63abToXx35hDQ5i7wWj0w75wScqQl9UNIG8+w5S/TEYtSGfGIRBQ3fuVP6LQJuW7YGGkyVfLpQCt73vI4VnoZJ4TA7n4nejzBTzbY/+9MPJL1kqceRa7slUnWCRKFMuAsihJYKvdeXwgNdy62H1PJUPHVdidycvaY/bxIVV5yvOYvy0Unv32Gv3V21/gfpudC8WVA== 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=Ia73iC7BY6+BwCrbTUotH5cvTTH8WPia56DguAvKwho=; b=Z94SKaj+4JxJbsteMCahFhqmwU1rZGYCFv4beOKtrjuSa6r9ye2P/e5Jiw5ajRn6Lyog2Gb4CtwI7+QVvvV6rkohK7b7LbC+NUkfn2IVBQIM1H4HMM1KAb3ZcK9mXIdTwFr8+fh5p4xYOu9rmc9UpaiOzoX7WB2z+AZeXb8kDb82vhEPq3l7VdgjqknTvnT++ywlVj1FQwb4viZwIJ0DeRHeq6aS1OT0Y8qJOyEKniICcllBtqt8Bzg6dOJj1mvsnl2LpgzztK3mEuAlNz1F4HK+fFdpsTbzjcy/+0f5Qmh/+r3IrdN+ZV7Ygr7DjEPt2iy2zvopRHVakGuoArcfjA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=intel.com; dmarc=pass action=none header.from=intel.com; dkim=pass header.d=intel.com; arc=none Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; Received: from IA0PR11MB8380.namprd11.prod.outlook.com (2603:10b6:208:485::21) by PH8PR11MB6855.namprd11.prod.outlook.com (2603:10b6:510:22c::10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.315.17; Wed, 19 Aug 2026 05:48:27 +0000 Received: from IA0PR11MB8380.namprd11.prod.outlook.com ([fe80::ea8e:eec4:f8d3:f95d]) by IA0PR11MB8380.namprd11.prod.outlook.com ([fe80::ea8e:eec4:f8d3:f95d%2]) with mapi id 15.21.0315.016; Wed, 19 Aug 2026 05:48:27 +0000 Date: Wed, 19 Aug 2026 13:48:18 +0800 From: Chao Gao To: Dongli Zhang CC: , , , Subject: Re: [PATCH 1/1] KVM: x86: lapic: update apic_base and APIC ID together Message-ID: References: <20260818234238.618158-1-dongli.zhang@oracle.com> Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20260818234238.618158-1-dongli.zhang@oracle.com> X-ClientProxiedBy: KL1PR02CA0013.apcprd02.prod.outlook.com (2603:1096:820:c::18) To IA0PR11MB8380.namprd11.prod.outlook.com (2603:10b6:208:485::21) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: IA0PR11MB8380:EE_|PH8PR11MB6855:EE_ X-MS-Office365-Filtering-Correlation-Id: 6af4ff83-af1b-44ed-0026-08defdb57db8 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|1800799024|366016|376014|10067099003|11063799006|56012099006|22082099003|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:IA0PR11MB8380.namprd11.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(23010399003)(1800799024)(366016)(376014)(10067099003)(11063799006)(56012099006)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?eK+JR6m+u/ftjxTcYt7W5gsmf2hWjK15kAJlO+vRDPjWXjATUPwP/GUDhh0h?= =?us-ascii?Q?pPP6wdF/eig3tbYfcNKdcyAionm9VkXP+Q4jz5ilGO7E+iQmIoP38NowcbHn?= =?us-ascii?Q?gn/OxaoslcjOBrP1ivA8rqcCxOZ8qltLGerr+5cCxwvk196vnKA49RuVF5Iu?= =?us-ascii?Q?unl9/TUxrMmB9XAi5A+sYhfJS+2FiR4s4VqyGrLs30kOYgBMmp6L0wdvGjx2?= =?us-ascii?Q?XQImdsrFzTkfG9FQ8Tg5SYTSJAEoQ42YWIItElpcfdvTbDQIwwi6Pn4oAw92?= =?us-ascii?Q?YNzBfmWTF8TizB5ancsXBX2KF59In2f6cUsWK9fAvH6FnwfxhVkxKNvFSHVw?= =?us-ascii?Q?KP3YJRU9dvaQVREuboLGPaXVjzR2LQYhcj91LDAPDbu5GIjOuI3lpdIo2VXK?= =?us-ascii?Q?pZxM5pw466n1HZNpDCKxMRHvhJ7+sCIJL6LgR2KexroHhji4XdTFfp5+YG1f?= =?us-ascii?Q?5o4dN/XrPE6lhWYFMfvdObGrvLTOZUIDrNBCTwzOmAZIOeqzCJjeycZTMx5V?= =?us-ascii?Q?gjd8VSBkIZ2sLuv31caU2lDNy10rICR6LFeD/xo24MdSZkIrKwG/nd4vjptj?= =?us-ascii?Q?OM4dvlNvj6oWZuwLCChJiFzNq/rOuqB0wdvFAKquG2RQ9PZSh138j4CDCFtK?= =?us-ascii?Q?TpEw1WVA0tk/D8uzz+vZCUueT3eTW9tidLQL2kj09xpMyf0KZ6hKGg1fO3oA?= =?us-ascii?Q?gkKMqA9a12ByxyXbbdvGVmZPetuOrxKKB94PoYGXfpToq+/+koS3Jvr01EIk?= =?us-ascii?Q?XKUHjyeb7o6puZXueEylRh6A3LpuwSDtAHqrDzJGtVKNFMTSfkQ56KP3ucFX?= =?us-ascii?Q?iTFPwjHOfdghK6bMo/CJWqYHL6ZjpyS999CXTsVOMzYHkIoSRpIyjDs0Retg?= =?us-ascii?Q?xEw6Iw4OmmncdLIXyFzGKSge2jGQezoMIHxu6zpWAwfaLlnRhnAujRdd0f3n?= =?us-ascii?Q?evW0yRPPVs4cj8BNk/9mWvmJdgvUN7GwqlS60QbnIdfMHdhj3F4G6QkgSz52?= =?us-ascii?Q?R2SmCxctwoOlkwcrA0nGc0dU6DK17cGNgYyOQumFdMcQaraeQve5dach1GLq?= =?us-ascii?Q?Ux6JTev6JJC7iWlEuI/K4wEom/FvdngE06sso2wgMkmoN+EUFGLYxmNTK4j7?= =?us-ascii?Q?7ZARbhtouW5XmER4U94bgFTgEpdf6ApMSMXdX9G3l9tgV4rw/gDbEMAlNBNr?= =?us-ascii?Q?iD0BTCAXVmhfZitrXiEQlGuEYD7vcs6gwegeCeR0z9jxXFHzbbd9QvMtVV0d?= =?us-ascii?Q?VxIvANZhC+SEKhrBIOLq649UMLIH5N32ewSIfc2f+d6Q9nUKBdb2DfsI6mNj?= =?us-ascii?Q?gmVcFWLozz8bPFka0vGDi5pr6Vb7tSpvpguEvXZ0TKPdDb/pxsidf7qbUbEl?= =?us-ascii?Q?RS4w+aNlM+RNGYS10Z6Z1p+nQk3BnYInLY7V0syyqX3E5EZlzeXjGgt/dESw?= =?us-ascii?Q?nVOcy+TkYMfvzkKidIIfCXJvNY8xX4mJs5K5HprWPv9/dz60mYjWv0S2HmNT?= =?us-ascii?Q?BEnHbzUsfSHQaU9U7qR30D0CiD0dWyHosWCHQ7WdzUHpDWhH8rcyzbUA8no8?= =?us-ascii?Q?mFOKcTE6ohCrRaoKfL3fA5aUXPE7QlwtfM0XwyPMA6V0fsu8hMC0jFvxaHQG?= =?us-ascii?Q?Mj/YlHGkWd8cuEtZPjTxZbic6wgvZojqb+d2kbuaxGeOKoHxiex08qoHMbUE?= =?us-ascii?Q?twKUM4bTFJm31pd5FHy+JIVf5hjI9w86Gn7FiaLJbgVBWcKIvZf10+03WAFj?= =?us-ascii?Q?iYsl8nUtlg=3D=3D?= X-Exchange-RoutingPolicyChecked: Kpw2l3ZqPQOH4bQywqr1IEojCHB3CDFIOkdvh9C5udicXUOxwmdgPSjVaD1IcViewTRInfZRx+p7UtKdFwYJqBzWQNIgZn1HeuvCQzQhwWdiiG52FSkwRVVy/sDPAIAtaeNJTC1kcmIUenbSRJAesKnqFgyLXqvU0FNSlG0beW2zZdKt9nFdWXQXdhcctlWIrxYz0+QHRNpxQcJXsKKSDWyE1z3BVjdoyBzvhkq+VEC4ecN34J4c3wMOzN3/6wW3VdxmKpZjPJuYszgspeWF5zuMH1tNrn95gA7KqXyEmRtkjFGLuVI6DtF0VO7gJFxa4J7a9BMhgrMdEtPIAkdI8w== X-MS-Exchange-CrossTenant-Network-Message-Id: 6af4ff83-af1b-44ed-0026-08defdb57db8 X-MS-Exchange-CrossTenant-AuthSource: IA0PR11MB8380.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Aug 2026 05:48:27.7029 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: P4LRajn5PjG9iPUvsdIwQHDy4O0cD5H4UQyCs61Op0GV2p0Ng/ie5g4AtyfP0w1yGvDGnJ1GHwY/1JetBsjmUQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR11MB6855 X-OriginatorOrg: intel.com On Tue, Aug 18, 2026 at 04:42:38PM -0700, Dongli Zhang wrote: >The commit b2849bec936b ("KVM: VMX: Update SVI during runtime APICv >activation") resolved the loss of EOI issue when apicv is activated after >being inhibited at runtime. However, it does not resolve the cause of the >runtime apicv inhibition. Why lead with commit b2849bec936b? APICv is inhibited and re-activated for other reasons regardless of the race below, so that fix is needed anyway. The race is at best an orthogonal issue. > >The inhibition occurs because apic_base and the APIC ID are not updated >together. > >Although commit 052c3b99cbc8 ("KVM: x86: Reinitialize xAPIC ID when >userspace forces x2APIC => xAPIC") reinitializes the xAPIC ID to the >vCPU ID when userspace forces the APIC to transition directly from x2APIC >to xAPIC mode, the updates are not performed in a single transaction. > >If another thread calls kvm_recalculate_apic_map() during the window >between updating apic_base and the APIC ID, kvm_recalculate_phys_map() may >set xapic_id_mismatch and temporarily inhibit APICv. So the goal is to avoid a _transient_ APICv inhibit in a corner case? If so, please spell out in the changelog why it's worth fixing.