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client-ip=165.204.84.17; helo=satlexmb08.amd.com; pr=C Received: from satlexmb08.amd.com (165.204.84.17) by BL6PEPF0001AB4F.mail.protection.outlook.com (10.167.242.73) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9542.4 via Frontend Transport; Mon, 19 Jan 2026 13:00:18 +0000 Received: from satlexmb08.amd.com (10.181.42.217) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Mon, 19 Jan 2026 07:00:18 -0600 Received: from [172.31.177.127] (10.180.168.240) by satlexmb08.amd.com (10.181.42.217) with Microsoft SMTP Server id 15.2.2562.17 via Frontend Transport; Mon, 19 Jan 2026 07:00:13 -0600 Message-ID: <7a012575-bf92-4614-80e7-6bbe593f57cd@amd.com> Date: Mon, 19 Jan 2026 18:30:12 +0530 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 07/11] perf/amd/ibs: Support IBS_{FETCH|OP}_CTL2[Dis] to eliminate RMW race To: "Mi, Dapeng" CC: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Ian Rogers , James Clark , , , , "Manali Shukla" , Santosh Shukla , Ananth Narayan , Sandipan Das References: <20260116033450.965-1-ravi.bangoria@amd.com> <20260116033450.965-8-ravi.bangoria@amd.com> <82e836e7-c0cc-4226-91cf-4b2275d99e73@linux.intel.com> Content-Language: en-US From: Ravi Bangoria In-Reply-To: <82e836e7-c0cc-4226-91cf-4b2275d99e73@linux.intel.com> Content-Type: text/plain; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Jan 2026 13:00:18.5430 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 227b6924-86d8-4679-a62a-08de575ab273 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=[satlexmb08.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0001AB4F.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL3PR12MB6450 Hi Dapeng, >> static int x86_pmu_amd_ibs_starting_cpu(unsigned int cpu) >> { >> setup_APIC_ibs(); >> + >> + if (ibs_caps & IBS_CAPS_DIS) { >> + /* >> + * IBS enable sequence: >> + * CTL[En] = 1; >> + * CTL2[Dis] = 0; >> + * >> + * IBS disable sequence: >> + * CTL2[Dis] = 1; >> + * >> + * Set CTL2[Dis] when CPU comes up. This is needed to make >> + * enable sequence effective. >> + */ >> + wrmsrq(MSR_AMD64_IBSFETCHCTL2, 1); >> + wrmsrq(MSR_AMD64_IBSOPCTL2, 1); > > What does the BIT 0 of these 2 MSRs mean? Disable? Better define a macro > instead of using the magic number "1".  Right, those are disable bits. I'll replace those magic numbers with IBS_FETCH_2_DIS and IBS_OP_2_DIS. Thanks, Ravi