Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   "Li, Fei1" <fei1.li@intel.com>
To:     Borislav Petkov <bp@alien8.de>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "Hansen, Dave" <dave.hansen@intel.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "hpa@zytor.com" <hpa@zytor.com>, "Wang, Yu1" <yu1.wang@intel.com>,
        "Chen, Conghui" <conghui.chen@intel.com>,
        "Yin, Fengwei" <fengwei.yin@intel.com>,
        "Mao, Junjie" <junjie.mao@intel.com>
Subject: RE: [PATCH v2] x86/acrn: Set X86_FEATURE_TSC_KNOWN_FREQ
Thread-Topic: [PATCH v2] x86/acrn: Set X86_FEATURE_TSC_KNOWN_FREQ
Thread-Index: AQHY7bJPaJkWnW5TA0i9pVLsL611Fa4zoFSAgAqGfoCACvoBMA==
Date:   Mon, 21 Nov 2022 07:52:23 +0000
Message-ID: <SJ1PR11MB615392FC28992FD088E05046BF0A9@SJ1PR11MB6153.namprd11.prod.outlook.com>
References: <20221101053019.174948-1-fei1.li@intel.com>
 <Y2kkk+XqBP3u6ObI@zn.tnic> <Y3H44Rdi5ari6fql@louislifei-OptiPlex-7090>
In-Reply-To: <Y3H44Rdi5ari6fql@louislifei-OptiPlex-7090>
Accept-Language: en-US
Content-Language: en-US
x-ms-exchange-antispam-messagedata-chunkcount: 1
x-ms-exchange-antispam-messagedata-0: =?us-ascii?Q?pj0m43i75/AVYm5QsLDNLnFmQEfTx5gJYIS37680UhcXj8Aj9Mqm+2Xg7T/S?=
 =?us-ascii?Q?++OKtbTfbvBd+P/pPN7WJ8LsRu5bLHIO9zDm9fWSVgLMh6J30C70KQGH2im6?=
 =?us-ascii?Q?xgTGaNbYCpBT11F1ONRtNLBqs1xR4W6HvTbMhF2p+k2PWy9h2GEMiAWg0Otj?=
 =?us-ascii?Q?XObSia2KelBN6uVgRP38eitjZDyD26/2yakbG5pY+cHKf9uqvA0FF/XVrRV1?=
 =?us-ascii?Q?ZayX6RoYhQ8lbCoECM2KQT+kovgSkbjbRZpGfrIrXNgmm1ZGOX0gm4FVnW+4?=
 =?us-ascii?Q?gCRPb6khNKycEM5hadeYFR9hLXniUn0tOi0MElb66mDq2CCOtexpctgYwjVz?=
 =?us-ascii?Q?EmOdKHYgZbd9a+7sAVs41FWiSRuXcNH3/Wh5CJ4CZxqu+m+F4GuzMC9jxQve?=
 =?us-ascii?Q?g5oDsUU+nkVZ3F7JSreU3FG88z4sXkLo6KrSnhDpEyh0tVmLv6kl1eUC5Q4q?=
 =?us-ascii?Q?5lnAsH2/qqkv4q25aQcK2cf/YpdVBL8JaGH93eCf/JJUI9FliJI2nAc8bMW2?=
 =?us-ascii?Q?Gb9wuIP0NqZRzoLHfMlgLGifCQXXwW3gtkztWOlmOLmoDgGsQzaHMzFkx5CO?=
 =?us-ascii?Q?ROjUk3j7CES/ZNXAN1RvL+BFWLQS3KVtOrjPp1ROoK8yf91vwbKlnS8sTEWG?=
 =?us-ascii?Q?RJ7no24FVxfh5sYOZRTrC1SIJWo+R1bYcvTOIC1YdN44ZD+VMDRCRhPe+F/l?=
 =?us-ascii?Q?mbZ25hj+kCalO2GWWlMXYSk5M7mMtJgDidw4hpDBQtt5rzqoGaYSCaMEKk+i?=
 =?us-ascii?Q?8tbneSMGMpt1GQnDdklAo2tt0tPaE4CQ21vl5IEjSnydRtFo2qMgryjsXnfl?=
 =?us-ascii?Q?K9bRSyFeXIlc2otb8hcoOjOWQEgrraSlcVi8xhzKYybPlNw/EaTttJXl0dBN?=
 =?us-ascii?Q?hu0v3Hl0w0JEnIwckUkbXTtdHJqFOWAsw+Qh+rZ/buVy0H9RRxiKD8A7TYg3?=
 =?us-ascii?Q?3UVO6vCBS3GEU6d/gB3oTIvM6kl2tCt0pzBBRad1ozSM9Lu/9T+E0SjKdnnN?=
 =?us-ascii?Q?WaA8T3zwDWr0+ChR3sfCq6E6qqIGVzhMZhvfot+307zilaxqBnwqKeHZ7kQd?=
 =?us-ascii?Q?hSD0Wu8d/3c5wOn6CQjoluCoon9ZQ3wdpI81JEAStzjA/UXW2XG5vgXUp2ar?=
 =?us-ascii?Q?vNq3WpE6dULjp3hEb058rka9Au4omdtn3zv6l5TyLtm/kHbOWdgHOslkrXzU?=
 =?us-ascii?Q?JJXlI46IEEhcsU5vN63dgXhtVZL7yw/W0XutGC/us3XMX5ayHOqgz0AyTTdi?=
 =?us-ascii?Q?LSW6tlnGvX4KnRDFtXjRY+02pJIHjONHwYeLQ/hp3jVZtUw/M/RtPLziUgqE?=
 =?us-ascii?Q?z4kOwHKVQ+qfOR3K0fUbKXGDAk3RcSCge2/p1CG8SxwfwhcBzw+ZxppXIjPj?=
 =?us-ascii?Q?kNf/D9+1m+/vfHqs1bDmVkak0GGI/OLz86wa/f3c7oMmk2lRxAAOOst2cYqN?=
 =?us-ascii?Q?LHg3IJ8qTpXeJq6T8LHuGeFJBk7Qk2y/8iZbiQ7IoKhahgTGtEABDbQWzTEL?=
 =?us-ascii?Q?DYQk5VhqM/XieruAk1FPeyLo2uNliHIZm0YbIl445fzX4bNLTUQ3nUMex73/?=
 =?us-ascii?Q?GF6aJllFgSaIxSRm4CSczd4PChnc1hIhDbDQNj2q?=
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-AuthSource: SJ1PR11MB6153.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 65896d3b-0362-4ae9-7601-08dacb95533c
X-MS-Exchange-CrossTenant-originalarrivaltime: 21 Nov 2022 07:52:23.3227
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: CmViYJMuAQdwGpTt8YS0UebKGAfoGL1nf+TTpCuZhzCGDaG8XMH1yPOf2pARcn5pbRixruLlhm3nNjN3EkQAxA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR11MB7205
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,
        SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

> Hi Borislav
>
> Thanks for your comments. So sorry to reply you late.
>
> >
> > What if the HV has unstable TSCs? How do you handle that?
> >
> ACRN hypervisor assumes:
> a) The TSC runs at a constant rate in all ACPI P-, C-. and T-states (i.e.=
 invariant TSC)
> b) The invariant TSC is based on only one invariant timekeeping hardware =
(called
>    Always Running Timer or ART). ACRN main target uses for IoT devices
>    which are typically one-socket
> c) ACRN lives with temperature influence on TSC frequency
>
Hi Borislav

Kindly ping for any comments here ?