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client-ip=165.204.84.17; helo=SATLEXMB03.amd.com; pr=C Received: from SATLEXMB03.amd.com (165.204.84.17) by MWH0EPF000989E6.mail.protection.outlook.com (10.167.241.133) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.8606.22 via Frontend Transport; Mon, 7 Apr 2025 14:13:53 +0000 Received: from SATLEXMB06.amd.com (10.181.40.147) by SATLEXMB03.amd.com (10.181.40.144) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Mon, 7 Apr 2025 09:13:52 -0500 Received: from SATLEXMB04.amd.com (10.181.40.145) by SATLEXMB06.amd.com (10.181.40.147) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.39; Mon, 7 Apr 2025 09:13:52 -0500 Received: from [172.25.231.87] (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server id 15.1.2507.39 via Frontend Transport; Mon, 7 Apr 2025 09:13:51 -0500 Message-ID: <99ad29b0-e57e-454e-b9b8-63b33f25ab45@amd.com> Date: Mon, 7 Apr 2025 10:13:50 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/xen: disable CPU idle and frequency drivers for PVH dom0 To: Roger Pau Monne , , CC: Stefano Stabellini , , , Juergen Gross , "Boris Ostrovsky" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. Peter Anvin" References: <20250407101842.67228-1-roger.pau@citrix.com> Content-Language: en-US From: Jason Andryuk In-Reply-To: <20250407101842.67228-1-roger.pau@citrix.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000989E6:EE_|PH8PR12MB6843:EE_ X-MS-Office365-Filtering-Correlation-Id: 9267ae73-b516-4847-9716-08dd75de6d9d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|82310400026|36860700013|1800799024|7053199007; X-Microsoft-Antispam-Message-Info: =?utf-8?B?ODA2VlhoL1NiRFVoRnptWWc1aHNadkVTL29SdEVPd0RDOU5nM3NRNUpmeGlp?= =?utf-8?B?NWxwZXRzVlhHUFI1VnovMnRWY08zMTFlc1RYZ1J5ays5bTNrZE5IV1RSc0Mz?= =?utf-8?B?OVhSek14VktZa3hKM0RXaFhENjZLd09NbnV2dXBGdGRUc1FGK0tjOHZ1bHFq?= =?utf-8?B?dTBtMmk4bzkrMTdJSk1iS1dNOFBydXJqSWtneDJYRkRWUEtabHlpb2xmNjBG?= =?utf-8?B?QzkwWnY4cGRDQmFBTklmUElFdG5UUGNPN3phWTNwaWR1eWhBMlJ4OW9DcHFm?= =?utf-8?B?R29KejZFM3EwOWtwUG5KU2NrRlU2anpkSHJpb2w1bVV4MW1EUndIUlJacnUw?= =?utf-8?B?OURyN2g5RHIwTnRTTmc3ZXRQK0NOQ3RzaEtQckI2ejJqNUFuMnRlT0ZUZjhB?= =?utf-8?B?V0dVaU8vOTZxbVJOSlNScndGU0MzTVVSOCt3VUVhU2tDY1lPcHJWU3pCVHM3?= =?utf-8?B?c0Z4aUl2MVp3ZkplV0dWZWhIV3FuaWNnTDJEN01TRWtvUEM4ekhHTjdIekk2?= =?utf-8?B?REhaQXdteDkzL0VxOFg5NTVHWDNSN0l5Ykh3Ym1ucFhwSXNhTXRYdjlwWEZR?= =?utf-8?B?eFBQRnVpRFBjMzhXQ0pNOXVTQkVWMVcweTM1R1VYeXhKWkVZYTJIR2UyR3NO?= =?utf-8?B?NHljUjdqVWtxUUp3Y2RGYXJJN0c5UGI5cko2L2ZvdWd1RjFNa3BEekhxckd6?= =?utf-8?B?bWo0NWlTeUZFcjNITTdRT3ZWN2hjMXpITHNzTFh6RGtReDIveUdrQmV4UXNI?= =?utf-8?B?azlnaDg2U0Q0NzFjZDFxNUhxbEhGQjJmbkJIRDVBZThneGk1MlFFTmRDM3Vi?= =?utf-8?B?VWtMVGg0SkJYb0swcXprUTVhTEJFTUtuSGZwc0dCVkMva2NGMk54Nkgzdnlt?= =?utf-8?B?WE1INnZQYW96bUNFNGJVeGVJcFhIenBmR0lhbDJ0YUJ1ZWt3SmpMcytUN0pI?= =?utf-8?B?ZzFtSmZLTlZlL0hhNFZEWTBpV1BhUDkwVjM5OEtsRERYcVJXOXo3bitWTnNn?= =?utf-8?B?dkpLdCtpTTVpcHgyVld4b3FtbzRpNVdBV0ZQYllHY0RETDZFbjNCUURRRGVW?= =?utf-8?B?aUt4UEFia1h5SUZLcTZoN3hSMHRsR1RmaCtOcUVRc0NlMm5ZcmhqMUp5Tjhs?= =?utf-8?B?eEw0NTZUdUkxSzcrb1VjTmhtS285eE1wYUF5VGgzTGRzc2dOVkdPNUFLdEx4?= =?utf-8?B?L21ocUg3SVR0Z1RYYXZ0d0ZOcFJ0ZnhMOGdwYTRUbFBoOHJNUjJzTXNtVjV6?= =?utf-8?B?MTBRUHIwVkdlcXV3UWVrOWo3d0YxSDFGbGUzVmQ1YVBlSVYvbWc3RE5saFRl?= =?utf-8?B?ODM1Vk9vcUlHdDYxUW9RLzFKSzhrTDlsL1QyWmhaZTFON0NtYkNQczJCT2xZ?= =?utf-8?B?UEJCVHhMTzc2L3gyYTZMS24wSm5VL2F0enJ1NTVIL0MwYkZoT1RVNzhUdXJa?= =?utf-8?B?cXJpRS9ybWFTVkRYM2N6QlpzRDFsRC8wNXhlWFFtYnJzS1JPQTd2SHZGSXZ2?= =?utf-8?B?QmdhVlowSSs5RGlLQ2VkbGp4OWhnN05pVlZackdxcENOTUYrUDRyOExkdEJI?= =?utf-8?B?WjcxU1JWeDVGV1dIV1JBdUJ0OU03SDI0TU9reHRWemhlRlEzbWZPcUk5TVBV?= =?utf-8?B?RncweFRYeFp5c1pKQzJHbjVwQUNKTitwZEw5eEQzekxJb3dOYWU2MnpSb3Z0?= =?utf-8?B?NXllNWxiTWx6VGE5TjRrbWF5RHk3OXVTM3I3cjlRSUMxdldmNDBuOUQ4YTJs?= =?utf-8?B?aGJXNWloNFdLTEtaNmk4c3k4SGVKeXZtUkZwSjJJUmxEUTRRV2F0MGVHMmFm?= =?utf-8?B?ZmEwL09iajdQQW1ZQ1V0djM1N2NYaW5nM3lYeFRJSTZKVHIreUcvdWNhZ0pG?= =?utf-8?B?bmxIR091WkpnS2JhOG1rSTVTZUZjaVZZdWFpOW8rbVFwSG5aVVVuVmVPR3hm?= =?utf-8?B?Qk10UmltRDE5Y2JkV2V4YTZyT0kzbERISFlrRkdkek5RL2l0Q0x2YjQxUHFu?= =?utf-8?B?ZTBLeHhzekJBPT0=?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB03.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(7416014)(82310400026)(36860700013)(1800799024)(7053199007);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Apr 2025 14:13:53.7149 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9267ae73-b516-4847-9716-08dd75de6d9d 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=[SATLEXMB03.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000989E6.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB6843 On 2025-04-07 06:18, Roger Pau Monne wrote: > When running as a PVH dom0 the ACPI tables exposed to Linux are (mostly) > the native ones, thus exposing the C and P states, that can lead to > attachment of CPU idle and frequency drivers. However the entity in > control of the CPU C and P states is Xen, as dom0 doesn't have a full view > of the system load, neither has all CPUs assigned and identity pinned. > > Like it's done for classic PV guests, prevent Linux from using idle or > frequency state drivers when running as a PVH dom0. > > On an AMD EPYC 7543P system without this fix a Linux PVH dom0 will keep the > host CPUs spinning at 100% even when dom0 is completely idle, as it's > attempting to use the acpi_idle driver. > > Signed-off-by: Roger Pau Monné Reviewed-by: Jason Andryuk Thanks, Jason