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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=5l3qePY/1n+xM1joQFLQ/DuqU4YPkqsTmKVM66m0n10=; b=U/cngl9/13W+CwxAgnE2krveP/jRBxChZ1miqmFo5df7vzGvvkvUhCJe9j7ZDsJKBpgEZM198ho1C/ODIkj46eVcbrJqBBgIUnzg+fjj4awueDjv3I31o1r9Ot6feygbTBqk4l3pZOOwlwEsO/IpPRk7SM9DQrGlhYEgX02C1b0= Subject: Re: [PATCH 1/3] Revert "x86/msr: drop compatibility #GP handling in guest_{rd,wr}msr()" To: Jan Beulich CC: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Boris Ostrovsky , Ian Jackson , Xen-devel References: <20210316161844.1658-1-andrew.cooper3@citrix.com> <20210316161844.1658-2-andrew.cooper3@citrix.com> <1c5f3162-8451-5e6c-e5b3-e5368fc0a871@suse.com> From: Andrew Cooper Message-ID: <13a21f92-3275-64c6-8afb-27ae4f772171@citrix.com> Date: Fri, 19 Mar 2021 14:03:25 +0000 User-Agent: Mozilla/5.0 (X11; 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X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?ZlNlempoQjJXT2paazhSME00SnZMSVFadEdESzZ5R1NTbUc0eVpncW5PSTJv?= =?utf-8?B?WHhSaGtIRnpJUWZJK3VyNHR4SUdmazFmeXpYYVlIdTJ3Y1UvMm13bTdPOWFh?= =?utf-8?B?OUhtbTI5Nm8zVytVbUFpdzd4dXZVTzE4TGE0Q0ZHTTZBRzFOSmVobGJFWGl2?= =?utf-8?B?eDhVaDlDNjZ6SXM2YmZZc2h2WUM2OFdYVGt0V1dlQmd1bVRPY2lNdkFBR2l5?= =?utf-8?B?T2dkcEdTR2kxTGZwUnBxZStWUzlQR2FEcm1RdGFPVFN0ekNNdWxvYTh5WjFB?= =?utf-8?B?ZjNtaVBNcVNsdng1SFVNTHpmMXFQeE5MUEp2ZjAyZk02MjhmVnpTWDNVcjEv?= =?utf-8?B?cHNZNHM1V2tZbFBkdjRjWnp1NURNMDJ2MVRudUFXTmU2SzZEOHVob255ZVIv?= =?utf-8?B?RjVCQUdXS2hXOFB2N3hoWS9aNzI4eXo2SE1uSEo4bnQwSWpnaEpraHVzL1BF?= =?utf-8?B?eEZydkVuZ3pDQWo4Sm5XZXF3SnBLTzR0aTNJR3NNeERWb3Q3d2dCbTc2TXVR?= =?utf-8?B?RDhwcmNmNTVFVG56VEhWYUZ3TDk1Y2xoZ09ZWEpaaTUxeUZOT1kvb0pSS3BD?= =?utf-8?B?SzJ6WG4yU2NSZjNucWc1T0E3aHdzeWFheDlvYSsyTUx3Zi9XMDRWQVdTQnA3?= =?utf-8?B?S2c2NGJDdGpvNTdHVmRhVWI4L0cwOFJGTTJDV2tRWEhRVHZFMlBLQlBMTzhQ?= =?utf-8?B?ckJHZC9SOFZTWjNYTUgwWERMZUVleStFcDRJZ3F6WlNHeTRTdGFsWnRaclRm?= =?utf-8?B?OGkzNjgrYTUwWXRrWFhvVTV5eHRBMGRvQUpwZWtFT0pIM3lsd2NmR3QvL2dy?= =?utf-8?B?RUp6R0xGcDRjbE8vcTZFdlJ0Q3RNQkZCMWRvcW9Vc3hocVYxK1d3ZUYrdGMw?= =?utf-8?B?L0VkcUFoNGpTeVJmdzJRUGJWODdaaCs2RHE1OGV5T28rNEFhZjB6eDRBV1NJ?= =?utf-8?B?aXYxb3lsMjhXbC9hMFBwRGx4RzBRK3hqME0wM3Y1cWE4VmdzWXoxbjZBZ2k0?= =?utf-8?B?M0p3RlBVb1FLMjdFWkZHR1ViZTlUWmVYc2JRVndOeG5teFZ3dzYxSEtURjR5?= =?utf-8?B?Zi85c2lKL2ZPaXQ2a1EveHUybkZJb1VPSlFZSlN2WUdvaXp0T1RzajFFNnBq?= =?utf-8?B?VHpLZFpGVENKMVo1Q29OTjdJcGlMN2VhL2lUaDV6OGlYMTVERXkrMkhIR2ZK?= =?utf-8?B?QUpuemdyWjYvaS9RT2t0RzhlSnVySS9BcGN1MDVrQkRFZUMxYzNydWVEK3ZF?= =?utf-8?B?cENwazlLNVlQdzJjeEpxMkxmMG91NTk5RFNPcy9hbXdpSmc1Rmk2RXVqZkp0?= =?utf-8?B?dEJ3ZDdhZjlyVWF6bUtwa3lzcGdyRndhLzE1UzFobmtLSHVMT21vMHhGcjlL?= =?utf-8?B?U05PZ3ViTXFwUE1ZREZkSHNIYWFUN1FaeElwSUZPTHhneUVjUDhpOXcwaGd2?= =?utf-8?B?aUhNZi8xam9DRXhrS1VYTm01aXlnbU5vTDFoUkw0aFByWmV0ckcvREFwRFU0?= =?utf-8?B?UXplZWdWS3huMytzU21zcHBqV0JMVGxpYnRqYmdxNjB6WGIyNC9MQUhwelZx?= =?utf-8?B?OEVtcFNyNDA4alhjUkwwd3lIT282MitncWxKWDhtU1FJUDlxQ21zZ2ptRDJv?= =?utf-8?B?L2hVejBJL0xDSFdkTUQ1N3VUUS9oam5XdGt6L2ZPQlZUenl0SE5nallNV1NH?= =?utf-8?B?OVpINFFBUEtlUmFhckFMUzM4Mmc1WWpwWUFidC9JVzFUWXVGaSszTlljTWMz?= =?utf-8?Q?9KDp6UxeiY2QmaUWuNZCM7n75vEtpox5WhAAx3I?= X-MS-Exchange-CrossTenant-Network-Message-Id: b9120d55-5670-4672-f88f-08d8eadfc760 X-MS-Exchange-CrossTenant-AuthSource: BN7PR03MB3618.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Mar 2021 14:03:31.7452 (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: BqwpdsCZ0AyDIwsYrf+RH2vE9wbJZme3A2GZSbcPfprFkOMihQfX94WzlNio0HMLx7mE/u//bKJ5GUmk3krTaYZF34vQLRhrBAVqqNf70Og= X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR03MB5137 X-OriginatorOrg: citrix.com On 19/03/2021 13:56, Jan Beulich wrote: > On 19.03.2021 13:59, Andrew Cooper wrote: >> On 16/03/2021 16:58, Jan Beulich wrote: >>> On 16.03.2021 17:18, Andrew Cooper wrote: >>>> In hindsight, this was a poor move. Some of these MSRs require probing for, >>>> causing unhelpful spew into xl dmesg, as well as spew from unit tests >>>> explicitly checking behaviour. >>> I can indeed see your point for MSRs that require probing. But what about >>> the others (which, as it seems, is the majority)? And perhaps specifically >>> what about the entire WRMSR side, which won't be related to probing? I'm >>> not opposed to the change, but I'd like to understand the reasoning for >>> every one of the MSRs, not just a subset. >>> >>> Of course such ever-growing lists of case labels aren't very nice - this >>> going away was one of the things I particularly liked about the original >>> change. >> The logging in the default case is only useful when it is genuinely MSRs >> we haven't considered. >> >> It is very useful at pointing bugs in guests, or bugs in Xen, but only >> when the logging is not drowned out by things we know about. > So would you mind adjusting the description accordingly? Right now, the > way it's written, it reads (to my non-native interpretation) as entirely > focusing on guests' probing needs. Even an adjustment as simple as > > "In hindsight, this was a poor move. Some of these MSRs require probing for, > cause unhelpful spew into xl dmesg, or cause spew from unit tests > explicitly checking behaviour." > > would already shift the focus imo. Sure.  I'll try to make this clearer. ~Andrew