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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7B33C433F5 for ; Wed, 29 Sep 2021 20:05:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C5BAE61528 for ; Wed, 29 Sep 2021 20:05:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344400AbhI2UGu (ORCPT ); Wed, 29 Sep 2021 16:06:50 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:21770 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343734AbhI2UGt (ORCPT ); Wed, 29 Sep 2021 16:06:49 -0400 Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 18THeZ1w024139; Wed, 29 Sep 2021 13:05:08 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : references : in-reply-to : content-type : content-id : mime-version; s=facebook; bh=LzdZYpjIJmIzwTRsqVfi0x7NICvR7ImaS9pD8QkWRao=; b=TDh9bga64fBR8BquYHrxrvGSo/foMCYlUvu0VTwVVGkromTpGxf5J523yKybwGBpfY1U cT+5KD+xy9Nxw8GN+rMpsgqGu+1+CzveA2nqiE+nr98GKGKTJYaGksMw/HM38SCd49fX Oxp7kBPNSF2p3lHkUQxB0yIgjsVJfwOtChg= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 3bcvrh93ut-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Wed, 29 Sep 2021 13:05:08 -0700 Received: from NAM11-DM6-obe.outbound.protection.outlook.com (100.104.31.183) by o365-in.thefacebook.com (100.104.36.102) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.14; Wed, 29 Sep 2021 13:05:06 -0700 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=gg0GbWyzxfT0mEuscZawADnSu4ipSRy11rIHJljL4hK4007Q/xU2yR4lj/VoW+nf2EWx6OxpPk131wVYBkwPoLadFokY1tnt+Oy4l1AhFQ5xCMD5sXe5TVB7clHm59zQuVEfZeA7fI04bcUeZfrYcjj9Scw6dr/6ZIDjfqDkvnqD9Tzow4VGX8D7urjojUs9DY+rr740VcHD8I5A2jmv/2DCIKUNhjW99xdH0o3MfHwwP4lHHP5fDecUBkOpwgqt4vZCJDEv4dIacIKylMJDuELk4zfqhf9211ZbTcn/h/PYpygzZkCQ8g2gX6iywWXRkcMqGGvqICEmm4zTxuSlsg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version; bh=LzdZYpjIJmIzwTRsqVfi0x7NICvR7ImaS9pD8QkWRao=; b=BkyGXurWZ6uu+QpQjYzxxoOKlfNT1IR4viYOsLUH3V66GlX29kfFxSVTed2cy+ufFqhVAroAMxamwVcqKcmPh7SSGPHGLliGdmDB0Pd7UpKwbvnUcdj+q4YZEUS1IHD4ezdXpg2St0H2XsvQL2ELPkIj5TJqY6+OKxQjXzwwKkDkXkkU6bRQNHIzSn5DosW1guEEoYFn0W87XQcgEm1sOzpY89UvjB9/kV9UUX7SZ41+sj00VrNrxhG2nzIPXMON+476AjsHGgDg/bne/C12/OWZ7gi2Wll8CttaKXZgX8k+rouerFCRPy6h3JzUumlJeimVOLrkfqRhHT0zXeSRLw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=fb.com; dmarc=pass action=none header.from=fb.com; dkim=pass header.d=fb.com; arc=none Received: from SA1PR15MB5109.namprd15.prod.outlook.com (2603:10b6:806:1dc::10) by SA1PR15MB5094.namprd15.prod.outlook.com (2603:10b6:806:1dd::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4566.14; Wed, 29 Sep 2021 20:05:05 +0000 Received: from SA1PR15MB5109.namprd15.prod.outlook.com ([fe80::7d66:9b36:b482:af0f]) by SA1PR15MB5109.namprd15.prod.outlook.com ([fe80::7d66:9b36:b482:af0f%8]) with mapi id 15.20.4566.015; Wed, 29 Sep 2021 20:05:05 +0000 From: Song Liu To: "Liang, Kan" CC: Peter Zijlstra , Like Xu , bpf , Networking , Kernel Team , Andrii Nakryiko , Alexei Starovoitov , "like.xu@linux.intel.com" , "Andi Kleen" Subject: Re: bpf_get_branch_snapshot on qemu-kvm Thread-Topic: bpf_get_branch_snapshot on qemu-kvm Thread-Index: AQHXtMWNyKWclBi4s0iJww6HNTXDJ6u6n6yAgABLWQCAAAXKgIAAJheAgAAVeoCAAAoigIAAOogA Date: Wed, 29 Sep 2021 20:05:05 +0000 Message-ID: <0676194C-3ADF-4FF9-8655-2B15D54E72BE@fb.com> References: <0E5E6FCA-23ED-4CAA-ADEA-967430C62F6F@fb.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3654.120.0.1.13) authentication-results: intel.com; dkim=none (message not signed) header.d=none;intel.com; dmarc=none action=none header.from=fb.com; x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 483be325-a705-484b-dde6-08d983846de0 x-ms-traffictypediagnostic: SA1PR15MB5094: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-fb-source: Internal x-ms-oob-tlc-oobclassifiers: OLM:7219; x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0; 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:SA1PR15MB5109.namprd15.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(76116006)(54906003)(4326008)(6512007)(38070700005)(122000001)(6486002)(38100700002)(8936002)(66446008)(66946007)(64756008)(2906002)(66556008)(66476007)(91956017)(5660300002)(53546011)(8676002)(6506007)(71200400001)(316002)(6916009)(86362001)(2616005)(83380400001)(33656002)(186003)(508600001)(36756003)(45980500001);DIR:OUT;SFP:1102; x-ms-exchange-antispam-messagedata-chunkcount: 1 x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?Mfg/yTDsw5ohyq81W4yzhSI9fi/ub2neu5BWxXLpfhm5ZG/tLbEjU/vG01ed?= =?us-ascii?Q?F/EiEJpvoMBJMDJqtKmsoY9/6Yga2kOIQ1VE+LK6IfxF4TVocAV4VmPoFQxS?= =?us-ascii?Q?Qgm+n6HxhiO4FZ6k9LmizGDTpGyQJYvJpDJVsqQrDtk76TvS7xulPrxeK2+C?= =?us-ascii?Q?fpegVodmrmrJ9N1F/eGE3bWWs6b5TD1iSAczlovP0PYaQaAIs0MwR0XpDoPB?= =?us-ascii?Q?eixnM66Y1CoYiJTl8bougzKe1XigDDZnnE2oJVylZmVLv3PG5Nmd9MxhUKcE?= =?us-ascii?Q?BYVTjjSRv/GOHNOkPitv7Fu5i4a3VW7H7hkM98AUvxyru1khZ+QzjKOFJuiv?= =?us-ascii?Q?WY/zE+KQJ1zJjYobcb9ZdF2gMcZrwrOZxSU6Bsgytde6BuStdVARWmQZpY7e?= =?us-ascii?Q?E1i0E7fRGhTXYerbBY6qnVaYlLAwszmWLz2Rva9sGLx2DptuRa254fce3cBe?= =?us-ascii?Q?bDWrkRSKa4MNMgPv2hIM+uEw44eJvtj+oKcfQ1UVvDtwPHkeyHhbDoJKZKPh?= =?us-ascii?Q?vfVeYNVF0prd134JmngYFxhoARngTNqYnFCd3YQ2f0Xy2Zecpjs8F4f8Ir93?= =?us-ascii?Q?p64SgDSzXG3uSESCDE5UZ8fmi3/iV9ViuDrKmLYC2PWYV/XZsUxWBbva/gVp?= =?us-ascii?Q?BExC7Y20TvSJt+WAQKNJiXcMIijhr6t3AGLmURuiZ9Uf+5jK3DOM1oVu/E8t?= =?us-ascii?Q?1thqND6702FQ5VNnbt5u8DK1PD7q/jnVZerR2Tw8w8cMcJOCjRX38m63KJ1r?= =?us-ascii?Q?9YI5KCuRaIBjZehjDHhm/1KMxf/iKD9oLfuIVGLpkTxHgRtHltTJYZtWyspb?= =?us-ascii?Q?dWtpIlmYGgqOxwAqrNsCO0v+uXYVLr5j/vNFYm9PULvTGiT0dTaE7RL04C8R?= =?us-ascii?Q?GxtZfwBvEJvFm4xkQ8BXrZFz+ca4eiBF0zrdGqiLY4RqjLg/90cD/wSatiYp?= =?us-ascii?Q?Gw1Gx+2sPGG49ReQqw3zhdzNI4DOFtwXDhDy6WEMnZgBXrrqrVRpEA7ycTUn?= =?us-ascii?Q?7a8yOqnm/czJVTSzftFGJKE3sd+zikxsFy0D2cLb0RpgaSfTyveE8S9j5Z9U?= =?us-ascii?Q?7hTOn/VRzTW4Z30h+UvRw3fFbdqb71sE7DvsTFd5dtFG2c4TWlg25yCVYePp?= =?us-ascii?Q?MAgpJmFY7978C9DlpScqJ9ndRgmuvVFxlFnJoKv+dRTQLigDGLykdbzmKffr?= =?us-ascii?Q?1PVV57BHkitzOAiT80RLpL3NJCP9gMDoPss55h4MD3ldEcAHsxV/9drBOdOr?= =?us-ascii?Q?HamJy7yH1woUdgwsZQwcCaSGuY+Eg6OcZ1aOICc5Ri6BaLemCsvkdBfVkrbL?= =?us-ascii?Q?S7Fz6sO1agekJ0hiHdKI7bYteIKDVhimxM0EWiklatPdrfxKGTPzkZo3E80b?= =?us-ascii?Q?SxHD6Ic=3D?= Content-Type: text/plain; charset="us-ascii" Content-ID: MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: SA1PR15MB5109.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 483be325-a705-484b-dde6-08d983846de0 X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Sep 2021 20:05:05.0846 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: d3q4lqmEduAsTUl0oCXG2ICD0bMXUywW0rNXv10V7Zrb7qAzIfqyXSjxlbL/rkLE9tuOG4g1u/snpHTBaV2auw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR15MB5094 X-OriginatorOrg: fb.com X-Proofpoint-GUID: 0-mVKuSQOE3p3lO2mAvzarOGPu5qMiG6 X-Proofpoint-ORIG-GUID: 0-mVKuSQOE3p3lO2mAvzarOGPu5qMiG6 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.182.1,Aquarius:18.0.790,Hydra:6.0.391,FMLib:17.0.607.475 definitions=2021-09-29_08,2021-09-29_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 suspectscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 mlxlogscore=982 phishscore=0 lowpriorityscore=0 impostorscore=0 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2109290117 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Hi Kan, > On Sep 29, 2021, at 9:35 AM, Liang, Kan wrote: > >>>> - get confirmation that clearing GLOBAL_CTRL is suffient to supress >>>> PEBS, in which case we can simply remove the PEBS_ENABLE clear. >>> >>> How should we confirm this? Can we run some tests for this? Or do we >>> need hardware experts' input for this? >> >> I'll put it on the list to ask the hardware people when I talk to them next. But >> maybe Kan or Andi know without asking. > > If the GLOBAL_CTRL is explicitly disabled, the counters do not count anymore. > It doesn't matter if PEBS is enabled or not. > > See 6c1c07b33eb0 ("perf/x86/intel: Avoid unnecessary PEBS_ENABLE MSR > access in PMI "). We optimized the PMU handler base on it. Thanks for these information! IIUC, all we need is the following on top of bpf-next/master: diff --git i/arch/x86/events/intel/core.c w/arch/x86/events/intel/core.c index 1248fc1937f82..d0d357e7d6f21 100644 --- i/arch/x86/events/intel/core.c +++ w/arch/x86/events/intel/core.c @@ -2209,7 +2209,6 @@ intel_pmu_snapshot_branch_stack(struct perf_branch_entry *entries, unsigned int /* must not have branches... */ local_irq_save(flags); __intel_pmu_disable_all(false); /* we don't care about BTS */ - __intel_pmu_pebs_disable_all(); __intel_pmu_lbr_disable(); /* ... until here */ return __intel_pmu_snapshot_branch_stack(entries, cnt, flags); @@ -2223,7 +2222,6 @@ intel_pmu_snapshot_arch_branch_stack(struct perf_branch_entry *entries, unsigned /* must not have branches... */ local_irq_save(flags); __intel_pmu_disable_all(false); /* we don't care about BTS */ - __intel_pmu_pebs_disable_all(); __intel_pmu_arch_lbr_disable(); /* ... until here */ return __intel_pmu_snapshot_branch_stack(entries, cnt, flags); In the test, this does eliminate the warning. Thanks, Song