From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3477EE4993 for ; Wed, 23 Aug 2023 12:22:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234903AbjHWMWy (ORCPT ); Wed, 23 Aug 2023 08:22:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231228AbjHWMWw (ORCPT ); Wed, 23 Aug 2023 08:22:52 -0400 Received: from esa4.hc3370-68.iphmx.com (esa4.hc3370-68.iphmx.com [216.71.155.144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C906E9 for ; Wed, 23 Aug 2023 05:22:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=citrix.com; s=securemail; t=1692793366; h=message-id:date:from:subject:to:cc:references: in-reply-to:content-transfer-encoding:mime-version; bh=R1897+tXoaCMui5Du0UAPEmDPfyvvi/ZosEeAVaoH/o=; b=hGdmNhsbiPht9pMFgOYQzvPcfvJLyXdqD56l8OCjbXL7SjSjbGknELo3 we7A8SpsKs99eOMTNfDCmNl8PM2rYkX2oxbrU9i65qOZn5mtQhL5sKoxg OKhx8/SOHFnbyv+8ShPYcHECalnG/lmVbz5BMq9v2Qyk1kMFL+6/dYn/Y o=; X-IronPort-RemoteIP: 104.47.55.177 X-IronPort-MID: 123069257 X-IronPort-Reputation: None X-IronPort-Listener: OutboundMail X-IronPort-SenderGroup: RELAY_O365 X-IronPort-MailFlowPolicy: $RELAYED IronPort-Data: A9a23:PGOhz6jU3Giww2nwKE7yqvFRX161DRAKZh0ujC45NGQN5FlHY01je htvXG3SOvqLZmuhco0ib4i3808EusPdmtYyQAJp/CgwQX4b9cadCdqndUqhZCn6wu8v7q5Ex 55HNoSfdpBcolv0/ErF3m3J9CEkvU2wbuOgTrWCYmYpHlUMpB4J0XpLg/Q+jpNjne+3CgaMv cKai8DEMRqu1iUc3lg8sspvkzsx+qyr0N8klgZmP6sT7AWFzyB94K83fsldEVOpGuG4IcbiL wrz5OnR1n/U+R4rFuSknt7TGqHdauePVeQmoiM+t5mK2nCulARrukoIHKN0hXNsoyeIh7hMJ OBl7vRcf+uL0prkw4zxWzEAe8130DYvFLXveRBTuuTLp6HKnueFL1yDwyjaMKVBktubD12i+ tQjND0CVFPdhN6I44LrW+lDj/4fNuL0adZ3VnFIlVk1DN4AaLWaGeDgw48d2z09wMdTAfzZe swVLyJ1awjNaAFOPVFRD48imOCvhT/0dDgwRFC9/PJrpTSMilEsluGyb7I5efTTLSlRtm+eq njL4CLSBRYCOcbE4TGE7mitlqnEmiaTtIc6TefjrqA72gDMroAVIAYGa17mgtO3sw2/YcheG XBN5AsfjpFnoSRHSfG4BXVUukWstAY0Ut5RHutqrg2AooLW+wGYA2IDQxZCZcYguctwQiYlv neZz43BBjF1trCRD3WH+d+8qTK0JDhQLmIYYyIAZRUK7sOlo4wpiB/LCNF5H8adltDpFCvi6 zGMojI3i7gagYgMzarT1VrOiS/qo5/GQxQd7wDbGGmi62tRfISiYZ6p71nz9/tMLI+FCFKGu RAsgMWX6uIFJZ6KkyOJTaMGG7TBz9qMLjzQx31mB50o8Ryk/nLldodViBl4JUQvOMEeeCTuf mfIpBhcopRUOROCYrV6bIGxI8Ary7XwG9P4UPzdcttJZN52bgDv1D1hYV6422HrjVQ2lqc+K dGXfK6R4W0yDK1myH+8Qbcb2LpynCQmnzqMGtb80git1qeYaDiNU7AZPVCSb+c/qqSZvAHS9 NUZPMyPo/lCbNDDjuDs2dZ7BTg3wbITX/gad+Q/mja/Hzdb IronPort-HdrOrdr: A9a23:xAuOzKjjjnr/bXX3uK3ovRrUPXBQXv8ji2hC6mlwRA09TyX4ra CTdZEgviMc5wx+ZJhNo6HkBEDiexzhHPxOgLX5VI3KNGOK1FdASrsSlLcKqweQfBEW2dQtt5 uIGJIObOEYY2IK9/rS0U2VFMsh3cnC0I3Av5ai858nJTsaDZ2IlD0JaTpzy3cGPDWu06BJb6 ah2g== X-Talos-CUID: 9a23:ydfJG2HLVF7JEVaGqmJc6EMbIIN7cUHj70eAMk+XAFxVUpaKHAo= X-Talos-MUID: 9a23:x2Y25wS9D6v3MmVSRXT3lA9naeRC7Z3tCXoXkKc64telBA9JbmI= X-IronPort-AV: E=Sophos;i="6.01,195,1684814400"; d="scan'208";a="123069257" Received: from mail-bn8nam12lp2177.outbound.protection.outlook.com (HELO NAM12-BN8-obe.outbound.protection.outlook.com) ([104.47.55.177]) by ob1.hc3370-68.iphmx.com with ESMTP/TLS/ECDHE-RSA-AES128-GCM-SHA256; 23 Aug 2023 08:22:43 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=ZUT9MAkp+at8frzP+6PiFeG1XPEz9GktYi5tsNF1verbFh1BMI0qAvtUaznhneVJGedFEvkAa8w22mFYZA83o6aLKAVqmRT4AtYcc+dxlW/Vg+y6TlnFEBTBs2txdTtu6CS2fRc8ExOUiRlQbQD45GXirrQZp/xsSu3YxNmMOZFl0tncCcps4lqifhYCVXQ/zeQ01/DsI7n8J0gkJlzTh2zgud+qTRXyeSWQ51zvkipfQwutr7+tKnP/Oh0kjKwWwnszuXJgcsAAgohWvOVJ7nOOTrOVLWuMUKVKlDn9KpppkiUSOHlOd/XdiPUh0b7HrJa2GHukVFTV9i/48QQ1cg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=R1897+tXoaCMui5Du0UAPEmDPfyvvi/ZosEeAVaoH/o=; b=HAOvDnXsLyc6CJAULjdmfyuPNUUdjr8vUic3OABvpYrvfanxy2nS4+epYYr1hO8nFtEPojYHxY4Xh0r5CehchenaqVspw/RBR24PMcO/JAe4VJ8GE8CjroVKTXcBBAeWoB5IxOWtpS3nlJr9r9EOwvA0ZgK9oRzbOWvUys3meSjSbEU27ic5489UAPn6QS3V9G+JZmKOKBcLkzoKeoo5nMuaY3yZNgOsDGv5YdZrNbepBulwndqz4amJY8WiGIsbkPXn2JHG+CpfqjPz2D7Alsq095vG+5DwwzJ4RUslieIjkbeQFalZJ7ZxufEn3zzIWq2yiyBlt1W51X3M5m/+IQ== ARC-Authentication-Results: i=1; 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=R1897+tXoaCMui5Du0UAPEmDPfyvvi/ZosEeAVaoH/o=; b=Klf50ZKPILpB05regeBn8v7/hk524MXv/+kGmytYiuMt6uJylSOVTWhfblPTHgHDHrrlF/2sMEyXsa/lXV3KW1CDrsNlxATSRFaeaQimPIagAHAxYxeXJ1+7Bt55C1iw5pY3eF/sMjKUeGLepBsBplMKl0UNqUQh5eASm7VZmDA= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=citrix.com; Received: from BYAPR03MB3623.namprd03.prod.outlook.com (2603:10b6:a02:aa::12) by SJ2PR03MB7139.namprd03.prod.outlook.com (2603:10b6:a03:4f4::15) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.6699.25; Wed, 23 Aug 2023 12:22:41 +0000 Received: from BYAPR03MB3623.namprd03.prod.outlook.com ([fe80::afa:50df:158a:a912]) by BYAPR03MB3623.namprd03.prod.outlook.com ([fe80::afa:50df:158a:a912%5]) with mapi id 15.20.6699.026; Wed, 23 Aug 2023 12:22:41 +0000 Message-ID: <22eb07b3-6de4-9fc2-fb05-2c7ebe6dc951@citrix.com> Date: Wed, 23 Aug 2023 13:22:34 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 From: Andrew Cooper Subject: Re: [PATCH 02/22] x86/srso: Set CPUID feature bits independently of bug or mitigation status Content-Language: en-GB To: Borislav Petkov Cc: Josh Poimboeuf , x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Babu Moger , Paolo Bonzini , Sean Christopherson , David.Kaplan@amd.com, Nikolay Borisov , gregkh@linuxfoundation.org, Thomas Gleixner References: <26a3421e-3a88-b326-4c4f-abdaa2262852@citrix.com> <20230821140619.GBZONvWz+iwQZwx/sC@fat_crate.local> <20230823052007.GBZOWXBymcCUOoMax3@fat_crate.local> In-Reply-To: <20230823052007.GBZOWXBymcCUOoMax3@fat_crate.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-ClientProxiedBy: LO2P265CA0187.GBRP265.PROD.OUTLOOK.COM (2603:10a6:600:a::31) To BYAPR03MB3623.namprd03.prod.outlook.com (2603:10b6:a02:aa::12) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BYAPR03MB3623:EE_|SJ2PR03MB7139:EE_ X-MS-Office365-Filtering-Correlation-Id: fc1ede2d-3035-467b-96cb-08dba3d3a55f X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:BYAPR03MB3623.namprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230031)(376002)(346002)(366004)(136003)(39860400002)(396003)(1800799009)(186009)(451199024)(6666004)(53546011)(6506007)(6486002)(2616005)(6512007)(86362001)(66556008)(31696002)(4326008)(5660300002)(2906002)(7416002)(38100700002)(82960400001)(54906003)(8676002)(8936002)(66946007)(36756003)(41300700001)(6916009)(66476007)(316002)(478600001)(83380400001)(31686004)(26005)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?WFNBTzNFQmlYSThPaS9IbVpGLzJhbE9uSzRHRzJXQ3JESnZqOTJ2MTlkSm5C?= =?utf-8?B?OCsvaTlBK0tJcllDRGt4NGpoVmE3SDhUSHpNQ2xBSXhoejczQ0NRM0RDR0N0?= =?utf-8?B?TGg5K3Q0K21qYzhocjZ3TmU5MlhpLzZEQkw4SXZsTVhIa1cyQ2E2Y2w2ay8x?= =?utf-8?B?a1dEWUtpbXduVi9VWnh0OWlnc2h4QW1aZ0NlRXozNy9yTnJtZjM0RWlITm1C?= =?utf-8?B?MGdPOFpWc0JJbUN2NlM5MHBQR3pPTjJTdXk5YnRnZWNVNVNJeTNwaFYwalds?= =?utf-8?B?N213VjlGNjRQOEFVUkJYVC9Td0lFeXRRdFM2Y2pWcXlOUmVHZTRPNTBiWUpO?= =?utf-8?B?RHJLTnFkaDBpamRPYXNPWk9QcWNzd0RSdWROZ0dpZnlRcktXV2xQZ2J0V2Zs?= =?utf-8?B?dmtUSVpXWkwxS2w5cGZpZmlpTWlvMGQ3QUhJZGMxWEN5NHM4TmN3RXZXdDg2?= =?utf-8?B?aDJnNS9xODFUVFBLaXU0MkFmQzlwa3RnSDRLYVo1K3lDNitpWFdWWktrbmlw?= =?utf-8?B?eUhNdTEvNzV0Y3lKQkY2cXZtYnlMZExoZTF6WTBSSm5iT0YyTkljY1hMZXND?= =?utf-8?B?L0dHZmJtVEUyL2ljNC95dVo2eTE1azdNT2RtWUdzUzQrUmh1ampYN1BON3Fp?= =?utf-8?B?UTlkZFJMVkI1TmhYV0hmTXN3OWs4RVdVQmdBOHZVaHM3RWxtcFhCWmNDanJH?= =?utf-8?B?cG0rUVZqQXc1dXowSlYwNDVmQUxwcUZpZWN4Z2lScThZUTI2S2dTTHYrcHd0?= =?utf-8?B?UHhOSUxxSGNMbDk5SEpwR2hDRDkxdGRkakg2WDM1NWR3TG42bEFtS1ZaWThE?= =?utf-8?B?QzBDamJsbVJyOG9oWm9VTUtEd0NUTERsQUxUemg4M0RhblRNYVY5K0F2Q3Rz?= =?utf-8?B?Zk5iSDV4YW9BV1pxcW1IREI4VW1kNmVXVEpDdzhmeHVYR0NuSXRBTXI4ek1I?= =?utf-8?B?Tkp1bEZhZkFxRE5JcTM4b0ZyeDNPdmJ6b3ErL29rUDZWaVFFVU5MVXBmMXlG?= =?utf-8?B?M0RoYll4UG9wd3RFbXA4ODlvcWxmQ1dGRGRVMWxSZkx6YTFRT1lJVEo4OXR6?= =?utf-8?B?dnRzMEliS09ZbFJBZDh4WURQWEUxY0J1bURKY3hDMUFSanhjZEpIYVllMkhL?= =?utf-8?B?WW8vekV6NllYSDRlVFpTMkYvZ3RBaGZzaG80aGVPN2tYSlpyeE5pVXNrbEJE?= =?utf-8?B?Mlo4UG00czNVR0Q2VkJqUmduL2gzYjQzckkrYnNaL1F6aVcySnd4RldjT1pV?= =?utf-8?B?aTZkRU45c1pFWDFMV1hMSlNlTnB1VWpyaEt0Z1dzb2RCbzQ4RXY0RlNzU29N?= =?utf-8?B?My9qd3FLQkRnR1U3Q1BtcFdUbXNFT0tkTE04dm9UT3diZTFYcjB4ZW1oUzcw?= =?utf-8?B?NjUvdEVNaW1ZZVVJL0ZCQzJUbEw3ZU5yVmpBOGdUcVpPZEliRy84R2VZNkY2?= =?utf-8?B?elErdStnMFEvY1IzYWd5dWU1eWVRajNvWjlCTldaVGw3bjFDanordVo3YnVs?= =?utf-8?B?RzFtek9pL0ZWNHlGeThMU3MzR1BwNWRsd2tCRXl5QXpOOTlSU2VCa1VxaHRs?= =?utf-8?B?RWErWU4yZHVwWWhxaWtNWEppbFU5bU82b3RKRHBiREJiVnZkMG50T29XTGt1?= =?utf-8?B?ZUxmd0RGTTRUeGwzOTd2MUczaUd5U0ZqcU4zbms5WWxpdjRpd0IxYU1CSXha?= =?utf-8?B?Y0g3WHh0SjcwNHh5bHBPSXZsOXptbDJQOTRyb1Y0aC9HQTVQaUVGbzlrTXdZ?= =?utf-8?B?bnVscnVGcDdBUXVxR3lEY0FZamtnTlVYN1NOSGxNVFJUV1VFeFlSYzl2QmFv?= =?utf-8?B?RzcvSlg4V0M5M2xkdDBaYWxzRlNwYlZMUFk1R0RQcWdab0dsYTU0a3gzbmFT?= =?utf-8?B?Q1lwbHQ4MENabkZoTEkrK1krYmRnVUc0OWNpK0FDSDlHc29KUGZSQjdWdlZn?= =?utf-8?B?WllKWDRFVElnSmxJNG5OUzdzSDBTVFFDRXFGUFd0djZpZFR5eXVLNEpscTBl?= =?utf-8?B?ZXdlV1dKQ1RiV0JEVzRRVmV5R2RncDRGSm9zNlVBczBqWmhzQkJHTTVGMHdv?= =?utf-8?B?dWdUcy9nd0tvZzRVUWpJd0xhVlhXTXVaUXd3OWY0STJqMUYweXg3OVk0a08y?= =?utf-8?B?cjQzci96M0xSUjZ6NTJOaWdCMUJ4Wk81ekdmSzR6NXJVS0J1ejFocHZHdnBB?= =?utf-8?B?TFE9PQ==?= X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: =?utf-8?B?TGZKbk12eE5WQk1BeE9UNnhteUtoQkh6ZHVnTWl2OGY4RCsxamJ3QnBWZnNT?= =?utf-8?B?cHdHMmNWeHVNbjNlZlNEVHZsdUVlbjkray9IQ2tKMnlhM0tYdzg5VmdPbVl3?= =?utf-8?B?VnZjV3VSMmd1RzY1WVN4NWlidnpKL0Z4eVVvaU1welhwRWZnWW1HTzRYbFBQ?= =?utf-8?B?TFZkWU5PdklhVXUzUjQ5cXJKNkRKamVFZmpiSHlzOFI0TWkycHJ6dzlkMjYr?= =?utf-8?B?ZzBuTnF6YmxybmUxU0wvU3RLbGhOemRsR1IrVGxKZEpOak9WeWpLLytvQW85?= =?utf-8?B?UGhCclp2aWJoZ2VvS1pXSjJmc0RMdkRNenQ0VFg0RnFQdy9JT0dvNmwyWWli?= =?utf-8?B?b3FBcHJ0MXBudDRuWEtiaU1seW5nbm94WHpiTERkNmFQNG95b0pGeGdWRG1B?= =?utf-8?B?ejczOXVGRkV1dEowc2d3bExKWURkTVJxRWY4S0J0akFZbWVFb2twaFZkenJE?= =?utf-8?B?WWp2YW8yZGtqWGU2WFJnaEtSckZqWS8zMW5ETlYvMy8yc3luaytkekxHVFpt?= =?utf-8?B?RjJwZ1haYVNpUkFOQjlrRmhNVzdNU2NpN0FIMFF5eDBLd0p3b291V29jcXNz?= =?utf-8?B?OFgzM0M1MVNva2QxVHhFNG94QkNNblA5b0dQQmh6Rmt6WkEwZDVNam55cXV5?= =?utf-8?B?dWkrMVR5Y1laclowUWlyRU8zMENOWlVLbnJYa2NzczFLdWQ5dzhrb0lPd04w?= =?utf-8?B?M2paRWIrdS80RnV4YzZySDBIbm1Lbm56TkNzWmlCbkNhL1hjeW9IZTFOY0tX?= =?utf-8?B?Q1VEbjE2Mk9NdEJZSjZtWHFJeDhWNVFjRk5GUUhYbWxOTXhFQ2JmSzFIY2Vw?= =?utf-8?B?ZkgyemRGbndvcXNZNWhxbzB4WjVLY1p2OHVNa3dXWmxObEhBaHNheTBHclJm?= =?utf-8?B?bVJKT2JkYks2Rlk1WFFsWE1NNUlrU0xtREMrRXgyMDhXL1psdHE4a2VPbTVZ?= =?utf-8?B?T1hpRTNibnVva25aQWVnNERyUDk4REwwLzVXbVZrUUVGNUZETndFVml2WUta?= =?utf-8?B?M2tnaExqYk1rVlk5RGVnd01SZ3JhdzhjemZJMHVqRVV3UlFwdEtDWG9BL3BE?= =?utf-8?B?M3AyL3NKeTRDaEpuZmc4dEJNeHdPSE5MUlFVTEw2YmwrSlRKREpjSXZOblkw?= =?utf-8?B?emtRQzIrL2l3RC9zOUc0aHFXYVY3a1ZSTktTNVBINmhTekZSVHpyaEdiYm5o?= =?utf-8?B?azYvdmF6TXRzQ09XYUNCY3h3RnJjOG5kS2hGaUJHNTQ5N0FFaHdoUTdQWTdC?= =?utf-8?B?UWJzVWxwYkFYUUJPUnVKSnBmV005cTBTQVYzTUFsY1VSR2d5NGlsWWVCM2h4?= =?utf-8?B?cnRBVUlaT1Exb01rczdPUExxQ2FjL0gvTzRJR3hLMWRTbjUrV2p4ck1qeFh5?= =?utf-8?Q?f/3dEI8uJMBX+uBzd2DlK0LlznbUd2PQ=3D?= X-OriginatorOrg: citrix.com X-MS-Exchange-CrossTenant-Network-Message-Id: fc1ede2d-3035-467b-96cb-08dba3d3a55f X-MS-Exchange-CrossTenant-AuthSource: BYAPR03MB3623.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Aug 2023 12:22:41.4475 (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: WCPDRrhyTC14jtZ9C/+HREfzXvO9WMU6M+g7sCKaVyD8wyavoa20n0zbW7oI5am0DyO/wvUt5n7/qOPbRW7+OWOeFWmX5+nF7FtomPNBTK0= X-MS-Exchange-Transport-CrossTenantHeadersStamped: SJ2PR03MB7139 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/08/2023 6:20 am, Borislav Petkov wrote: > On Mon, Aug 21, 2023 at 04:06:19PM +0200, Borislav Petkov wrote: >> And I still don't know what exactly we're going to support when Linux >> runs as a guest. For example, live migration between Zen1/2 and Zen3/4 >> won't work due to the alternatives patching, for example... >> >> IBPB won't work either because we detect those feature bits only once >> during boot, like every other feature bit... > The lowest common denominator of features exposed to the guests, Correct.  This is what a hypervisor will do for the SBPB *CPUID* bit. > should > work, as I'm being told. As in, Zen2 and Zen3 should hide the SBPB bit > from the guests, for example. In my previous reply, I explained why this goes wrong when Linux ignores the CPUID bit provided by the hypervisor and decides to probe manually. > I'm thinking if anyone cares really deeply about live migration, anyone > should say so and then we can see what cases we can support upstream. My > guess is those who do, have enough engineers to patch their kernel the > way they want it... No. You don't get to take my code, break it when integrating it into Linux, then dismiss the bug as something hypothetical that you don't want to fix. It's not *me* needing to patch *my* kernel when this goes wrong.  It's me (or VMware, or HyperV or one of many KVM vendors) getting a bug report saying "my VM crashed on migrate", and then having to persuade Debian and Ubuntu and RH and Oracle and all the other distros to take an out-of-tree fix into their patchqueue, then release another kernel, and then come back to this thread and repeat this damn argument. I'm just trying to cutting out the middle misery here. ~Andrew