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mx.microsoft.com 1; spf=pass smtp.mailfrom=citrix.com; dmarc=pass action=none header.from=citrix.com; dkim=pass header.d=citrix.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.onmicrosoft.com; s=selector2-citrix-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=gQ+DOZS6TOyBdKU5fGxUfNiaZ+kp3h/7e1sctlHNhts=; b=b/0RWyJIUxWZoAuYgakDZieAP3+tC4TJa6PAF95U/iAQNIR041zgl2CgMgPs3r1bSfYb4w4sO8GBFmXb0xqRZEWoI/rMjIwBtHKMDTdeHne10Cu/DI77enBHoLCvoSFlNO5MTqiRuuQNIQYbIbVkaZG25H17EHfUCBqltQWCJpA= Date: Tue, 19 Oct 2021 14:45:54 +0200 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Jan Beulich CC: "xen-devel@lists.xenproject.org" , "Andrew Cooper" , Wei Liu Subject: Re: [PATCH 1/2] x86/hpet: Use another crystalball to evaluate HPET usability Message-ID: References: <9963c7a2-f880-66fc-8f12-b1ddd0619c91@suse.com> <3a366ebf-61ed-7e41-193e-131540e555e4@suse.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <3a366ebf-61ed-7e41-193e-131540e555e4@suse.com> X-ClientProxiedBy: LO2P265CA0500.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:13b::7) To DS7PR03MB5608.namprd03.prod.outlook.com (2603:10b6:5:2c9::18) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 4c00ddb9-2d16-4ab0-6ca7-08d992fe6742 X-MS-TrafficTypeDiagnostic: DM6PR03MB4057: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:4502; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?L0pnenZsd0g1VnY1aDBtTlpmM243c2prNFIwWXVWU2I1SERTTWMxM1FrQTRP?= =?utf-8?B?QnNiUldmM1dLYk5rbDA3eWpBYnkvMzJyZG10VnZXVUdDUXFBT2NzdXZKcUM2?= =?utf-8?B?Z0xKRFJQQTFjZ3NhOVoyWkhnUGJsbHZuNWdKUklHTGNGRXhYdnEySW9SSEt6?= =?utf-8?B?cmtjdS96aGZ6aWliOEJiMzVkUjJEd25IcUpuaTVFc2YySVBmQ2UvRDdJS1hP?= =?utf-8?B?V0VvV2ovVTRHV2luR3p3Ri8vVzUxNEpYSGFoYjlMYXBVS0lQV1pOY2g5Slpi?= =?utf-8?B?bUJPbWhTb3FDYVF0OGJFckpuZlg4UjlpS3owWjdJMFA3djFubGdMODlsbjNk?= =?utf-8?B?S0JuSTNaQ3lGUGY0K2NkS0FSNlNJWnBGMUJRaFY2ODlQS1dRUVRhVGtPVmlh?= =?utf-8?B?OG9vcndqdXRHT1hFTWljY1BlWDNMR3pCeC9DLzQ4bDdnaDZrb2tHbmNRNUkz?= =?utf-8?B?eWJLNWRGQ0YrV2VtN2FkSXkzZ09xbEUvSHB5QkR1T2lHcWFZbUpCWnhxVms3?= =?utf-8?B?c0gwbkx6WWx3TlZyTDVWU1g4d1N2MU9nK3k3ZlBnYVJiWWVjRW1tdnF3dS9D?= =?utf-8?B?N0IxWk5UL01uSVcwalo0TUhpUlNLeVhzdS8yakc3eXFlYkVGUk90SnE5UEZa?= =?utf-8?B?NWE3d1dMcjN0dFcyeHR1YkgxdTJNU0xBSE5uUnZiTG1BRjFqRWJkN0pxWmJ4?= =?utf-8?B?VnVMLzA3Sm42cVlxdjI5ZTdCcThMalVvZ1U1Sm9qM25Uc0lET0pESjZpcklB?= =?utf-8?B?MEQ4Z0wyaVB5TFRXMjhEbzRsZnFESUcyeC9manhBWEdDcTB6TkcrOGZnVTNE?= =?utf-8?B?SXNjNTlSV09XN1lWMWV0VXUrWEVtWWsybDdSS2xGYUkvNk9IN2NlUUl6MUhN?= =?utf-8?B?TTNCU29OV0d2VmFJcnZXZjB2MStYeTRnNU1yZk42cExVR3B2Y2VKWUp3U3VO?= =?utf-8?B?VkpvR3VUeTlnNjRCRjkxdHlyczFHWm12ajQ2YmFrVDNVWUhPM3pFOUNnb0Ru?= =?utf-8?B?ZjA4bmZLYU9NQ2ZidXVLSC9TM2EvWjVwVHRDQjZuNGxjY25oeElKQUw0S2Q1?= =?utf-8?B?VDc4OVc0Mi9EWE1XUlZPdnE0T280aHF3WnBSMU5LY2F0Tmh6ZTNZQS9JK25C?= =?utf-8?B?ekh3amVzTVQ4M0lJdkJXa3VBaVBYZ2lmVDVpbVAxYTFtNnlkYVhLZ1BFcjg0?= =?utf-8?B?NEF5V3NJOWlheUNQMXZFcVdXNWd3K0t1Z3U3MGlweXo4UUZqTCtPVHNRYytZ?= =?utf-8?B?ZUZvSEZoSmUwTjFkejFIYW4zcUN2UW1LVHVSRUt6bXoyc3NveW5ES1F4NGk3?= =?utf-8?B?QVErM1VQUlRFK09XMFV6VmZCOTNRbjFueTVvUHF4OENMT1FXaDNIZFBsVk5z?= =?utf-8?B?cjdBMjJWb0ZSREVrMzJpQytTenpEZTZqOXNqN00xYlNSMDVYS09KYjZTeXVY?= =?utf-8?B?TVBiY0Q5NG5JNFBJc1ZlS0pHcVRlL2hQUlNHUytBdUxoNEVKN1U2T3BqN1J4?= =?utf-8?B?MVY2aUoxYjZ2ZnluOC95K1dPT0g3Q0JLa1lmM3ZaYXB1cjBaK00rOVlYc0Vz?= =?utf-8?B?QlltdFB5VzR3cStSclpDYmRLZjh1WDk4RnpXalJ2MUZORTRCam92cWxjVmZk?= =?utf-8?B?S0tMQUZwZS8ycmNtVGh0N1hqMktWeHF1QmVraDZ5ZTlKR01CaTRGMWMwd2c2?= =?utf-8?B?cWgwN0d5REYxZWE0ek1JTnRXeS9tRkRGRzBsV0R4aVR5bU5ZM1ROa2svV0VI?= =?utf-8?Q?V5ctQyhsLVu5Gj6FoinTVQf16FVV06/Y4ap38Fc?= X-MS-Exchange-CrossTenant-Network-Message-Id: 4c00ddb9-2d16-4ab0-6ca7-08d992fe6742 X-MS-Exchange-CrossTenant-AuthSource: DS7PR03MB5608.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Oct 2021 12:46:00.2485 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 335836de-42ef-43a2-b145-348c2ee9ca5b X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: OV7+eKfQYsV0EyzQocqnwG6OBEm69D6kwvpGvmCc48dhMFdpWQ3h/7CsizFKUj8G+0IrtsokDoFChsdIbe0UzA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR03MB4057 X-OriginatorOrg: citrix.com On Tue, Oct 19, 2021 at 02:08:38PM +0200, Jan Beulich wrote: > On 19.10.2021 13:30, Roger Pau Monné wrote: > > On Tue, Oct 19, 2021 at 09:07:39AM +0200, Jan Beulich wrote: > >> From: Thomas Gleixner > >> > >> On recent Intel systems the HPET stops working when the system reaches PC10 > >> idle state. > >> > >> The approach of adding PCI ids to the early quirks to disable HPET on > >> these systems is a whack a mole game which makes no sense. > >> > >> Check for PC10 instead and force disable HPET if supported. The check is > >> overbroad as it does not take ACPI, mwait-idle enablement and command > >> line parameters into account. That's fine as long as there is at least > >> PMTIMER available to calibrate the TSC frequency. The decision can be > >> overruled by adding "clocksource=hpet" on the Xen command line. > >> > >> Remove the related PCI quirks for affected Coffee Lake systems as they > >> are not longer required. That should also cover all other systems, i.e. > >> Ice Lake, Tiger Lake, and newer generations, which are most likely > >> affected by this as well. > >> > >> Fixes: Yet another hardware trainwreck > >> Reported-by: Jakub Kicinski > >> Signed-off-by: Thomas Gleixner > >> [Linux commit: 6e3cd95234dc1eda488f4f487c281bac8fef4d9b] > >> > >> I have to admit that the purpose of checking CPUID5_ECX_INTERRUPT_BREAK > >> is unclear to me, but I didn't want to diverge in technical aspects from > >> the Linux commit. > >> > >> In mwait_pc10_supported(), besides some cosmetic adjustments, avoid UB > >> from shifting left a signed 4-bit constant by 28 bits. > >> > >> Signed-off-by: Jan Beulich > > > > Acked-by: Roger Pau Monné > > Thanks. > > >> @@ -395,14 +396,43 @@ static int64_t __init init_hpet(struct p > >> } > >> > >> /* > >> - * Some Coffee Lake platforms have a skewed HPET timer once the SoCs > >> - * entered PC10. > >> + * Some Coffee Lake and later platforms have a skewed HPET timer once > >> + * they entered PC10. > >> + * > >> + * Check whether the system supports PC10. If so force disable HPET as > >> + * that stops counting in PC10. This check is overbroad as it does not > >> + * take any of the following into account: > >> + * > >> + * - ACPI tables > >> + * - Enablement of mwait-idle > >> + * - Command line arguments which limit mwait-idle C-state support > >> + * > >> + * That's perfectly fine. HPET is a piece of hardware designed by > >> + * committee and the only reasons why it is still in use on modern > >> + * systems is the fact that it is impossible to reliably query TSC and > >> + * CPU frequency via CPUID or firmware. > >> + * > >> + * If HPET is functional it is useful for calibrating TSC, but this can > >> + * be done via PMTIMER as well which seems to be the last remaining > >> + * timer on X86/INTEL platforms that has not been completely wreckaged > >> + * by feature creep. > >> + * > >> + * In theory HPET support should be removed altogether, but there are > >> + * older systems out there which depend on it because TSC and APIC timer > >> + * are dysfunctional in deeper C-states. > >> */ > >> - if ( pci_conf_read16(PCI_SBDF(0, 0, 0, 0), > >> - PCI_VENDOR_ID) == PCI_VENDOR_ID_INTEL && > >> - pci_conf_read16(PCI_SBDF(0, 0, 0, 0), > >> - PCI_DEVICE_ID) == 0x3ec4 ) > >> - hpet_address = 0; > >> + if ( mwait_pc10_supported() ) > >> + { > >> + uint64_t pcfg; > >> + > >> + rdmsrl(MSR_PKG_CST_CONFIG_CONTROL, pcfg); > >> + if ( (pcfg & 0xf) < 8 ) > >> + /* nothing */; > >> + else if ( !strcmp(opt_clocksource, pts->id) ) > >> + printk("HPET use requested via command line, but dysfunctional in PC10\n"); > >> + else > >> + hpet_address = 0; > > > > Should we print a message that HPET is being disabled? > > There is one, and it was even visible in patch context that you > did strip from your reply: I meant something about being disabled for PC10, but I think the generic one is fine enough. Thanks, Roger.