From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-00069f02.pphosted.com (mx0b-00069f02.pphosted.com [205.220.177.32]) (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 776B7383C96; Wed, 23 Sep 2026 17:26:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=205.220.177.32 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790184372; cv=fail; b=ZfZU5n/PJf5sNUigL3BLP1vkT7HNxZmSAQIEv+4Q6iPG5Bb/Fb+gSfsVnPBS1wrn/MAgIp4neREY/mPWM5lEzafXE+9FxYUSO7H6mvOZGRzPMrK6KAvS3+XvdEYaPMtcx5GXe3W661Z7PDxp4vSzRN6g++jB0H9UedgmVBpFCf4= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790184372; c=relaxed/simple; bh=z8jqCNW7OlgJlptdqfMlccH6zvvQK/3N0sA9PqJO2eg=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=Eddj4tk5xUovBXwGjAr52IarwA10LRhXRbGEq/2rtj/8ulb3BG7HA28SRHLjCWR7zBkg/6nm5Eb+ziFAlW3D1gYxJJ8NmawGiIiNv86DNqvlC+m0ci/nyC0SPxPubTG9Wy+uywqd12zzegIwjkuC1DG4jiXyltjdz1BG5BOPo9A= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com; spf=pass smtp.mailfrom=oracle.com; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b=fjQxQZ/r; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b=LLZ4IWG7; arc=fail smtp.client-ip=205.220.177.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oracle.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oracle.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="fjQxQZ/r"; dkim=pass (1024-bit key) header.d=oracle.onmicrosoft.com header.i=@oracle.onmicrosoft.com header.b="LLZ4IWG7" Received: from pps.filterd (m0246630.ppops.net [127.0.0.1]) by mx0b-00069f02.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 68NErt1E2391957; Wed, 23 Sep 2026 17:25:38 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s= corp-2025-04-25; bh=bzeFiOyIyT8zYtgtmYcxL7TwHu2PZS4CR44T5EF94j0=; b= fjQxQZ/rP4dC8goPIuzPfvxR7lf2xVg8PGx6ocFSJVxhFPi/jWypy3CITjGdrVdv SQhWG3lbgOYgA3UDWcwRx3KfKRDhfnqECtyw9Zyekr7cF1rZsrLKgxFpxKDjBQOs JCYRk+I07TAaXGbgbIQa1jRbwA3bAxMgm245Mci86snype62f4vuUlXLqrL8iE8y ozz2FDPOsmagmAFDBPeE4SBX49zqdk1BCA2VXCmlJuULzH7yqo3HTtlKz5oBgtX+ P2Dwik6mEGUbqX5BIPjXMfqILXjUBUUKJRsiCrhCgSUbFxiLspSglOErPwZXT6/6 jGBIEEzb0/xbLgGn149Dwg== Received: from iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (iadpaimrmta03.appoci.oracle.com [130.35.103.27]) by mx0b-00069f02.pphosted.com (PPS) with ESMTPS id 4gsk1ge85m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 23 Sep 2026 17:25:38 +0000 (GMT) Received: from pps.filterd (iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com [127.0.0.1]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (8.18.1.7/8.18.1.7) with ESMTP id 68NHKPpw038281; Wed, 23 Sep 2026 17:25:37 GMT Received: from sn4pr0501cu005.outbound.protection.outlook.com (mail-southcentralusazon11011069.outbound.protection.outlook.com [40.93.194.69]) by iadpaimrmta03.imrmtpd1.prodappiadaev1.oraclevcn.com (PPS) with ESMTPS id 4gu1rc0ymm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 23 Sep 2026 17:25:37 +0000 (GMT) ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=NIjS+jL1RS0RiTw1qjxoPJ3wWB4fH50DhoTFk/4SdWpONpcS0ABOtInfZA0JnVAbs5lsT/MoEBHCR35WEwD+cuiJzgYN/68MoI4+WbN0HQ20q4OLvQI/XuBU/cnWBZlSfkwnaAedFwqmEytLghsIC2hxVjD56dLFG67F6LEVdDOsGu5m+ng9LXzJCuPrZCVT7vv1J4a0ez756zkP/xq1zYGCaTjE9ZW2e0qaMf+M6qqGCaFgG5rl3v6VFJlndGEN6VSbvcpiV2JBh2J2Wt0lfJglj6tXy2HOIYjfhL0w1Pz6rD/oinNNCHcorCiZuXCjTFD/y0uK4ql/eJD4j5PnRw== 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=bzeFiOyIyT8zYtgtmYcxL7TwHu2PZS4CR44T5EF94j0=; b=gTkj2kjZ/geIgnCrqDcMHOD+9uvB59KSXHEg4AwH121uKJa6aX8HdQYnAm4WotqkiXNFGGWpCPNzqYm5/TCT7tqb9esKzmAbbLkjKKHjAbju3idQVONfNjylfQl9gXlmbTFHFZ5mNsXrf/Jn8+YoZXkVzWdpfU8mjn6a0BxW/A+nL4nlnv6BZ2G2oYlnWHb5OnUhaoJT1hojCpg3yHDNXI4lefqTtFRbHHhrELo4TsTLbZ8k5pSWkb7oT5H/VzxOYVrAOxzTBnXjPKOtlQhffNfv8BTTd2UfbH2r124mDVU6fkzumkn/RO8xpWWnNJPvalLqqv5nzeoQsF2/jurJrA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=oracle.com; dmarc=pass action=none header.from=oracle.com; dkim=pass header.d=oracle.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.onmicrosoft.com; s=selector2-oracle-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=bzeFiOyIyT8zYtgtmYcxL7TwHu2PZS4CR44T5EF94j0=; b=LLZ4IWG7BoOsTUcQWRPudJFpGuodYOezEqvtpGgPGz3kOyhSSRFbnvx3wpKzUF4cSgGtpoArfZJdWKrOvk1RI+SZD3DFKnzyZmzVR3MTQCd/RBLTbaOpsIkAfUpAY75k3dulXA/RqG5wDZLAbHt7xNkks7A3LDWljpnkZuJWm1s= Authentication-Results: mx.microsoft.com 1; dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=oracle.com; Received: from CO1PR10MB5506.namprd10.prod.outlook.com (2603:10b6:303:161::7) by CH4PR10MB8075.namprd10.prod.outlook.com (2603:10b6:610:236::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.451.14; Wed, 23 Sep 2026 17:25:31 +0000 Received: from CO1PR10MB5506.namprd10.prod.outlook.com ([fe80::da72:a0a9:5f18:cda4]) by CO1PR10MB5506.namprd10.prod.outlook.com ([fe80::da72:a0a9:5f18:cda4%6]) with mapi id 15.21.0451.004; Wed, 23 Sep 2026 17:25:31 +0000 Message-ID: <02e6b16a-67d0-439e-868b-435fe1c38400@oracle.com> Date: Wed, 23 Sep 2026 10:25:28 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC 2/2] sched/core: Defer preempted remote vCPU task clock updates To: Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com, dwmw2@infradead.org, joe.jin@oracle.com References: <20260824012716.753022-1-dongli.zhang@oracle.com> <20260824012716.753022-3-dongli.zhang@oracle.com> Content-Language: en-US From: Dongli Zhang In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: PH7P222CA0024.NAMP222.PROD.OUTLOOK.COM (2603:10b6:510:33a::24) To CO1PR10MB5506.namprd10.prod.outlook.com (2603:10b6:303:161::7) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CO1PR10MB5506:EE_|CH4PR10MB8075:EE_ X-MS-Office365-Filtering-Correlation-Id: 1f12aca2-d626-4622-e0fd-08df1997ab06 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|23010399003|376014|7416014|1800799024|56012099006|10067099003|4143699003|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:CO1PR10MB5506.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(366016)(23010399003)(376014)(7416014)(1800799024)(56012099006)(10067099003)(4143699003)(22082099003)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?U1djc2U2ODc5REJHTzh2TmgxZmVZYXhBRENTNFA3ZjE0cy9pS3dHTEloTGVi?= =?utf-8?B?bnlSNi9idjloTC9reUh3V0lpZjdQdGFrbVJ4WldwK0NRQVNlS1J5V3B0dXFQ?= =?utf-8?B?aUNPenFPUEJXa1BzWGlyY2xTb1RkcUFzcUg0U1cxVXNaRFlVODlWWXc0aENJ?= =?utf-8?B?dWtHVy9hNVZFUW1sdm4rcE5BMVowZUoxZ21ZSC9iMmZlZWxKZWNPbVdWaDZ3?= =?utf-8?B?NEpuTkNERG5McHBuVHVockhnSWlLcS9HTGlzUStNMHFYSFBMWldDUXNNSDRq?= =?utf-8?B?aDNkRmpBQ2ZjQU4wTEFNbW4rS1ljclAvaE5wck5jR3VSNVlwUThVNkdQdGlS?= =?utf-8?B?YlEzTlloV2kzK2xIZlVXdHZKalFjam1LRDdVeHpvTndKVUt4R05XNU9LZ1ha?= =?utf-8?B?bzNDRDFFMXhmYU5wWThxekgrYS94bEd2Zm9YOTlLOXlSSFBIUkJTZUpHeDhy?= =?utf-8?B?MWxIVlVRaWpzWU53Nk9IL2syS0dabWxYL256V3dnR21MRnkzdEYyZTR4Q1ly?= =?utf-8?B?UHU5NGhJUkhGZ1F2c2lGclNKN1RzMmFIeitLN01BUjhGKzkwc0k1bWc5aVFo?= =?utf-8?B?Ni9jSnpRSnlUdG5QUmJvcWhaZ285Rm90Tm8wMjYzREhtUXNCaFRQMDlRSFRT?= =?utf-8?B?bzhGS0JRdDlud1lqVjlJNmpJVnQ3T0RyNmhoMEx0cEk5YWMyenUzVTlaVzhW?= =?utf-8?B?NUNGOHpEcXlkdGVNQXBTZUdqNkQyV2d2NWxtK1NVMG54OEc5a21QanpRNFU2?= =?utf-8?B?cTc2T2FtTlZsL3NiaG5nN2JXQ01CTzRMZXhOL3FNcE1wTXBaWldnblhmdDVq?= =?utf-8?B?ZkVCOFRxY3dIQ3VNNkYreEcvWlVoWjdiWU54Zmk1bnF3aXdzS3VZNC9YUnM0?= =?utf-8?B?a2RTYW1LRnQxZXY3V2pocjM0RENxN051bjVTM3l0QmVNVTN6ZFJ0VndvbVk4?= =?utf-8?B?WENxMlppNWZiUThYaGpZT0dZU1JEZ0htSWZJWjJLaitGSjl6TklzOHloS2Zn?= =?utf-8?B?eUplZmFLRUNoRnk2QnFFZUNnUTZ5NjdyYkRyU3VDUjBYMWtkVG5kMlB6RmFL?= =?utf-8?B?M0U0ZmdRVXZwT3ZKK3ppMkNlZEE0VS9sK3NHMHltaEdWVDhPT0xTbHBVUSsr?= =?utf-8?B?M0NISmszNGNrK21zamgzeGtwK3lJTWNuV2c1RUhBNWFkc0ZhK3A2UFptQ251?= =?utf-8?B?VDM0VHZzMldPYXNYbWZlWjhsa2taNGZ0dXpVNi9oSzh5MU1RcDV2MlFRWFJ2?= =?utf-8?B?cVo4dVNVTHg5Z3h4SWZSNUJtSTVJa0xPL0tTeXR3MkdRanhicHprcm9mZ0J3?= =?utf-8?B?eDZKRVdHblRKOUlnc3FIaWFkZFBFMGpCbU13emdqWEUxSkw4TFo3TVgvbEVt?= =?utf-8?B?bkEvalNTNFF5a293eE5vdkxaWjV3aklZbHpwbEtxY1g3eWdjYkVmL1ZLTzY0?= =?utf-8?B?bTlkWXZsSDRHR0RxRmlIUUlZNXZNbTVocERUWmVGeU80Z25rNWJsYUErMVRz?= =?utf-8?B?Y0MwbGVIVUpHZi9PMWdqRlJCNjZkQ01qWk9Sd0NjNXFNZTFLZ0ozd3I2eVRw?= =?utf-8?B?eXJiTHVsdjkvL3hhOFRPUnkrZExjQ3ZFc2psbmVteWRlUE1zZXZWRzkreTBK?= =?utf-8?B?RWdOSlJvWS9ZcklIa21JZGZFMDlTVlY5ZE9QYU5KajRFczBIWjdDOVJwSlV1?= =?utf-8?B?ci9SYm1icVlaWlBHWk9qNGwzdmt2NlVIYzNlNy9BOXROR3RGaFV5QW0vWHZJ?= =?utf-8?B?M2Z2elpVUjZ6UkFoV01ta3pBY3FTUU1IMEdOM2NueEpSSVJRRnRUWEo0UUhI?= =?utf-8?B?Zm9GdVB6L1ZCT3YrbCt4L2Y0UEUzaHh2QllVOGh4MkxxR0FsQU9xdytna1hq?= =?utf-8?B?bWNmUDFhTkJkTGxqUnhHY2NUbWpSWDZ5N1Bob3dEamVBZVBxd0FaYmFqYXBo?= =?utf-8?B?N3lOOUJSZWJBc1NRVit5c1RoUnpLN2pqWEg1YlRzTGFnWjB0MTZmbExYaHYw?= =?utf-8?B?WTdlaHpqMUV2ZzRJVkhiOGFaZitlUHAzSW84VVdpdnVsbVJuZ1NRQ3R3azJF?= =?utf-8?B?Y1dRSm0rRTYrcUxOeEZVQlpSRG9naW5EQkp6T3UzVEJDWkVSMGxhT1BCRU0z?= =?utf-8?B?L3dYUVFsZjA0Y2l4OTQ2bnRMYmd1c0ZWbVJ4TTJZUzlYbDZRZm1aQTNYamdJ?= =?utf-8?B?YnlVS2tUUitzMUFmUTdtb2xBdWhabU9Fd1JPODZmUlh4ZWR2QkJic2RZT1VF?= =?utf-8?B?dmg1QXNBU2RIQkNGdzArNEJiajRtbkxKKzFhVnVPbHBNOFVIeDlkOEo0SW9o?= =?utf-8?B?a0d2Q3lza0pmRmM2QVl6cHpWclpZNmxwanFUaGxiZCtoR0l2KzRRQT09?= X-Exchange-RoutingPolicyChecked: QljQBZziOzhY5VNH3rW1TLnrJ9xoaIUFOB1JT1DWqydpNN3P7jQxFMLjThgfVKfpAOKtFGa3oeWQ4oqUK3F8/Ysl+nvM12bAQFdP74agrd483JSIChSb1TaNrU2tJ5fnezzdyIEdkaJ/fMnp+AA8jbSlGJfC7ilgQMsA7WZcwZ6GVSdHlOqX5op6AQtTRMBdAuFZgK6v65RfUQM1BBKsAGDXDc75QTWec5iWLu0I9aeVk7vsOjQrMsnRI2iToVeBQR4zI9Ii+q1pnTzE6xQ5VVccCjs9o9bXe5aPrE6/e2YQywMSvKSVdUrK18uv581dxo8RAYtmDdb9j2LyUtq2gQ== X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 28ogo6TsIlBFNrDhcoROSxv4zEPjgwMUBmIwdtBkYD/BGSYcVLOzR9NquTbMQxMSu9tH2g7JjEvSatGAeEw2P/svVl9Kxdz1neOJoW78B5CS7w3HzNJ7fsPpMtjKbsj2QjgnY33r3YE0YJxf5B4kpa0vtOvOPPHOnAHbI4QIwlKXnXf5rAQbfB+7GbBmLM+F7AIZKbN7WDX+mvLMaByt8tPq9xpqs6N81Iw3z7XdwaUupQWXMtHySmkHEYObqTB3+NijYFMDQ5JBa7MParmW8P/zDOSd96OCLHJ0doDuC9Y9nOnd0ZKh3loqhrLtbS5VE9zMGKgNCeEE0bP22yqKsmTq6I59GZP/VIxDGNyDKRHCqJl7Fbsbg56eWgrVXv5hVkpPyTrjaKc+011xOFZkLq+PIc4P/EkVuTeYNDcYwVgYfyLzTWPaHLMFOXvgXnzuT9y4kOLU3WQ+K41PKvH9NNXO5KoNk15gME91hzoIdT9QkzgvE0jx2BsdvghqdW/fHrPQI+CJ3oT7MGSqMEA4JWTHGd249vIpSLF9AbjCEqsdMYhSfkTts6SadW2gFKyyBiOZMQQgDt5ixTLXYl6Egezdf5tDSMOLVu5tIO/+tSQ= X-OriginatorOrg: oracle.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1f12aca2-d626-4622-e0fd-08df1997ab06 X-MS-Exchange-CrossTenant-AuthSource: CO1PR10MB5506.namprd10.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Sep 2026 17:25:31.1465 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: C8VFXF5CpwEjRIbBJyfh29626AYzsEO4eM1xnWM6AbkJK59rF0gocPneTq+26xB843giVL0/FNEmk8CsbmlwWg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH4PR10MB8075 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-23_06,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 bulkscore=0 lowpriorityscore=0 spamscore=0 suspectscore=0 malwarescore=0 mlxscore=0 mlxlogscore=999 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2609040000 definitions=main-2609230069 X-Proofpoint-GUID: CKGFUIlnROEN_Xe_MbQQvTuYYrUBf-1n X-Authority-Analysis: v=2.4 cv=T6sZ3PKQ c=1 sm=1 tr=0 ts=6ab40b92 b=1 cx=c_pps a=qoll8+KPOyaMroiJ2sR5sw==:117 a=qoll8+KPOyaMroiJ2sR5sw==:17 a=6eWqkTHjU83fiwn7nKZWdM+Sl24=:19 a=z/mQ4Ysz8XfWz/Q5cLBRGdckG28=:19 a=lCpzRmAYbLLaTzLvsPZ7Mbvzbb8=:19 a=xqWC_Br6kY4A:10 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=GoEa3M9JfhUA:10 a=VkNPw1HP01LnGYTKEx00:22 a=jiCTI4zE5U7BLdzWsZGv:22 a=x4eqshVgHu-cdnggieHk:22 a=-ACe4YRWzawKTbou7kUA:9 a=QEXdDO2ut3YA:10 a=5yU3S35YU4bGjq-dph-N:22 a=Bho9c0fBagfJEIQBS7DQ:22 cc=ntf awl=host:12107 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIzMDA2OSBTYWx0ZWRfX8yDs4LFkKvcL OxAZglJeyDiLHKs7MSBWRsk4GvO+wQ672rSIH0NoPTIsCpycC15JFo5q38KKRFx7/rco/Ps7Py8 yhhP2z5h/uy0n720+5/olXRH6ip1ZeoGJ7CyGg0vTHaPE2fOlBLt X-Proofpoint-ORIG-GUID: CKGFUIlnROEN_Xe_MbQQvTuYYrUBf-1n X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIzMDA2OSBTYWx0ZWRfX2IaQc5Xlk5S/ Pzzzd8KZ/Rjpma4coQCsmHUkq0L48l3nALfrlljehIUXLSCOnlvR3Dpa1psIzFL3SewAnYbAXsX OYDrL9ldI4hKiqzuAcLmk97dh6NRypHOxB2lOrNjrLkLzINWtUKDCmRJi/v4nPYFiHlNJrA5Y8l TEEAJGlz+4bkQUg2DniLrOWyECbhCP9+kUs63EF7HPZOn3rtlTfuCDf0J8cuOz48pIvR4oMyFX0 Emvu8h3iqfW3KXsSH0ZuoowpLE89zCxvfjLe6suumQLS+E1wBj+hFqmoBgDqSBPsW8SQ8BNwyWB Bq7g9pTtjtt4D1VhS33NrIPoprU2XToHXYU/At9FNrMq12SU1VqGFMOyJemMXyGpTeirahd3JPU yquXOlpipYOeHT4BN3opI/B7qej2iC21wwZCPQQyJlZC7qvAyEBHxCad+CsTdRkLRFCQDnBg5fp 9rgVGKJvYKMnVyy8W3ePcEtQruQ1iNN5Y16z9X1I= On Mon, Sep 21, 2026 8:59:08AM -0700, Sean Christopherson wrote: > On Sun, Aug 23, 2026, Dongli Zhang wrote: >> A remote update of a runqueue can advance rq->clock while the owner >> vCPU is still preempted by the host. KVM publishes the matching stealtime >> when the vCPU is about to re-enter the guest, so the remote CPU can >> otherwise charge the stolen interval to rq->clock_task. >> >> Defer clock_task updates made by a remote CPU while the owner vCPU is >> reported preempted. Fold the deferred delta back into the next update >> that can proceed so IRQ and steal accounting process it together. >> >> This requires the hypervisor to publish up-to-date stealtime before >> clearing the preempted data. > > What happens if the hypervisor doesn't do that? Because it's infeasible to > guarantee this will never run on an older version of KVM. > With an older KVM, st->preempted can be cleared before the corresponding stealtime update is published. As a result, the guest can observe !vcpu_is_preempted() and consume the deferred clock delta while still reading the old stealtime value. Thus, the stolen interval is incorrectly charged to rq->clock_task in that update. On the next update, the accumulated stealtime delta is observed, but it can be larger than the new, small rq clock delta and is capped to that delta. Since prev_steal_time_rq is nevertheless advanced to the new stealtime value, the remaining stealtime is not accounted in later updates. That's why I tagged this patchset as RFC, to seek feedback on whether there is a better solution. Thank you very much! Dongli Zhang