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client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by SJ1PEPF00001CE9.mail.protection.outlook.com (10.167.242.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8356.11 via Frontend Transport; Wed, 15 Jan 2025 05:46:06 +0000 Received: from BLR-L-RBANGORI.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Tue, 14 Jan 2025 23:46:02 -0600 From: Ravi Bangoria To: , , CC: , , , , , , , , , , , Subject: [PATCH v4 2/9] perf/amd/ibs: Remove pointless sample period check Date: Wed, 15 Jan 2025 05:44:31 +0000 Message-ID: <20250115054438.1021-3-ravi.bangoria@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250115054438.1021-1-ravi.bangoria@amd.com> References: <20250115054438.1021-1-ravi.bangoria@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ1PEPF00001CE9:EE_|PH7PR12MB7456:EE_ X-MS-Office365-Filtering-Correlation-Id: 90479e99-654a-42a3-b40e-08dd3527e81f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|82310400026|376014|7416014|36860700013; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?DlB3aL5UxUPIQp91ZK+R55HoO4JIOrYvzddf7Wbr/asp1ysyZHffUpp8FMzR?= =?us-ascii?Q?cFNbc7tXq++jP9CP2pEdHskuNFZYtZs6hbNMuo+K/CYN9XmaRlZjxTjfeEt2?= =?us-ascii?Q?jIhXA+DmQZw7hOc5o3Z1IUklRO6IBJ1xzkwGUihpzBBLiKU3ZuGoT8aw3edP?= =?us-ascii?Q?92B7gZU9ETTjXhAOfVZxpzZeeWUidUwCg7GZ+MeF3wvnQAit2gXZIdtQrrK5?= =?us-ascii?Q?vKocXYXJ8eqoedtcG30LOut2hl4YDxOurXrM4hY/LBZbU05iPaj9QXsvP4KJ?= =?us-ascii?Q?7Z0ieyCJo9EpEl/DNEhTXsad8OOJzmxw/tVeqX2U8HVS1O1+Wiq6fKAJM0+6?= =?us-ascii?Q?LHSuj45Hec7xFEDNwyEvg8yujLjh7ianYYADHD0Wb8n50Ur7nXlg7WObKpur?= =?us-ascii?Q?Ybntvnnn9DFFTlANU4beqDtPIlEqGviH6s24WiSkcvoah9vUtDOQC/qfsk1n?= =?us-ascii?Q?YHWIwoehuHAdGdiflPiSDz4OUiRhkv8zBLwyzv7ZRaQBnBFbF+/8c4z80u9a?= =?us-ascii?Q?WdIRvvX1PTBpdg6Wild0/2w0AacBeA34KxvBYhkoevRyTblBlO4a0m+aL9pk?= =?us-ascii?Q?ugwGOzhxyFG+Deq7brknO+lAbaS0y1IOnA3ynQlStoT5RvCWK2WnjZ4qjKQ1?= =?us-ascii?Q?T2Cqog5LFHh0JpFiCE2VbVYdVOhdzGzM4i15So0koAAXgMoBCcFoOs06LJ1J?= =?us-ascii?Q?v/v0kybaHOmC55YcdlFz/lifZHL7dE1drXrC55lNFNqYOJv1zA9LlaisNBB1?= =?us-ascii?Q?GMqUfUmKtPVkakfjx2NS/S2kh9zp+yRjTIqy9TFJAXLkYsxv+fGfFQqhdloX?= =?us-ascii?Q?p3NvF/p5r9upbh12yN+5roveV7RNgT4/gr0qFfe1UKyLthv9covPpW9vO7ON?= =?us-ascii?Q?QiBk+Qz3hnxleamHRRSIxDyOkazHHRliYuW/CHDRM4zZ5CWmX1lvjSELfn2s?= =?us-ascii?Q?Qdt400IE9uXf3HN/mLiZxoEZP20x3k2a41ePCRHUTxQM7imRofWa/8HimFNI?= =?us-ascii?Q?iuNzt9cNoRflOMwVWhobVZ8zngUtm4Fl8ZCW1dhx+cvLMReW69UjUoWjoGcr?= =?us-ascii?Q?vAO6H/Y3ibwEhIdB/BJ0nolr3hO1cBM5XbwAr4S0DUQOxiMe9Sj9R5N9SKfv?= =?us-ascii?Q?FgS2EunSdWgZLsi72ECm/BhU6P8hTYUJXEavtjQ9L18zPm6S1BTZViGks/69?= =?us-ascii?Q?BE4EgwOz6qSgRyOb9ZoAs9NODIbhI0u42cnoj/xDP+N+Pl7/mDpUhUb4hqrx?= =?us-ascii?Q?D2Pv3aBGsEHTWWZMIYNASqQJ5u4mMrddSteOJUqxMra32x4Db/jyXXuBuIoh?= =?us-ascii?Q?rOZNuB7XjdV3ZD4sR4cqbqLYHk9pZU4SmFMRI0evauV5kmrWnO09Zq2SgQes?= =?us-ascii?Q?IqvseBJOjS/+8R9r0PUZTNkUwV1uaRm0x0pQ+VCXVLN6rTNgp5OTPN/5prwg?= =?us-ascii?Q?RmteB/cs9l0bPRReJq5ceTW9o7vzRCdqd19ggTSPAMWoAWdZLK1/ew=3D=3D?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(1800799024)(82310400026)(376014)(7416014)(36860700013);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 15 Jan 2025 05:46:06.9304 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 90479e99-654a-42a3-b40e-08dd3527e81f 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=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ1PEPF00001CE9.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7456 Content-Type: text/plain; charset="utf-8" Valid perf event sample period value for IBS PMUs (Fetch and Op both) is limited to multiple of 0x10. perf_ibs_init() has this check: if (!event->attr.sample_freq && hwc->sample_period & 0x0f) return -EINVAL; But it's broken since hwc->sample_period will always be 0 when event->attr.sample_freq is 0 (irrespective of event->attr.freq value.) One option to fix this is to change the condition: - if (!event->attr.sample_freq && hwc->sample_period & 0x0f) + if (!event->attr.freq && hwc->sample_period & 0x0f) However, that will break all userspace tools which have been using IBS event with sample_period not multiple of 0x10. Another option is to remove the condition altogether and mask lower nibble _silently_, same as what current code is inadvertently doing. I'm preferring this approach as it keeps the existing behavior. Acked-by: Namhyung Kim Signed-off-by: Ravi Bangoria --- arch/x86/events/amd/ibs.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c index 4ca8006d2221..bd8919e7c3b1 100644 --- a/arch/x86/events/amd/ibs.c +++ b/arch/x86/events/amd/ibs.c @@ -307,13 +307,8 @@ static int perf_ibs_init(struct perf_event *event) if (config & perf_ibs->cnt_mask) /* raw max_cnt may not be set */ return -EINVAL; - if (!event->attr.sample_freq && hwc->sample_period & 0x0f) - /* - * lower 4 bits can not be set in ibs max cnt, - * but allowing it in case we adjust the - * sample period to set a frequency. - */ - return -EINVAL; + + /* Silently mask off lower nibble. IBS hw mandates it. */ hwc->sample_period &=3D ~0x0FULL; if (!hwc->sample_period) hwc->sample_period =3D 0x10; --=20 2.43.0