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Date: Mon, 9 Feb 2026 17:11:39 +0100 From: Roger Pau =?utf-8?B?TW9ubsOp?= To: Alejandro Vallejo Cc: xen-devel@lists.xenproject.org, Jan Beulich , Andrew Cooper , Xen-devel Subject: Re: [PATCH] x86/hvm: short-circuit HVM shadow guest creation earlier Message-ID: References: <20260209144049.86535-1-roger.pau@citrix.com> Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-ClientProxiedBy: MA3P292CA0040.ESPP292.PROD.OUTLOOK.COM (2603:10a6:250:46::12) To CH7PR03MB7860.namprd03.prod.outlook.com (2603:10b6:610:24e::14) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH7PR03MB7860:EE_|SA2PR03MB5769:EE_ X-MS-Office365-Filtering-Correlation-Id: 41a347c1-dce1-440f-ab84-08de67f5e9f6 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?d21qWkk2RjU0L2hhQmNicGpJOVBmcW42Zmtad2N6Qlorc2VKUjNyM05YUUht?= =?utf-8?B?YVFjT3RSWXFRck1aaE9SWHVwQThOWTVJWjdsY0dkc1U3VmhNMU5tRWN4aVZP?= =?utf-8?B?QS84cWRCOThvL3NIUU1McFgvOUJVOHA4bGg1dGxPNlBEVk12VURiaUZudmMv?= =?utf-8?B?cWZvY1VzWDhnZXlsS1lvNjh0bVhUbUdIZGh3enMrVGRSdndmUVZtcEtuM3Zh?= =?utf-8?B?QkdQY1U4VGxwUmJCanQ2UmM3WHJGeDZYU3RDY1BrOWRFQS9tSFhheVZwZGN6?= =?utf-8?B?RW9DK0p3MU5yTTcxYVFya2VZb2tHQUI5eGV2MW45N1BheU0yQWZsY3JZeWRi?= =?utf-8?B?VGJnY0dkbVhOaCtSblZyVy8xQUNab2lZVTNGb2t6bUsvTU9yTERDbnRKeHZ1?= =?utf-8?B?bE90c3BYekpxdzA0Ti9jL1dvNS93STJtS3RsZXZxUUEyTTdaVURoOGY1MUtR?= =?utf-8?B?TTFTSUZHK1dPVzFsclN5b2tTVjZJS0pIMWxITk1wRWRGSWQwQ2lHQ2hGNTRt?= =?utf-8?B?aTMrbzlNYUtjb3JPcHRPRFJ0eVNZNUZXem1UcVFtRWRpblJsL09uMXF6elhI?= =?utf-8?B?NkcyOXQ5a1dZMGNSakFDenZLVENtRWJPLzFEZzgxRFpLZDRKVUpPUllBYXpm?= =?utf-8?B?RDI4b1VvL0Z5bTZEV1VGZEJkTEYyM3NJM2RtUFRHcDE4bVZGS2xzNkVUbWhC?= =?utf-8?B?V1BIM0NPV0FNZXE1SGJHYU1GYWYrWmo0cjR3WGt5Wm1oc2hLZHUzSzNhMHdu?= =?utf-8?B?ekwyRTZiUlZiZlNmaStTUWYrMjZkb29vMnZzSFNLcUpqTXNIamhQd2hoOHBT?= =?utf-8?B?djFwRHRsYVhUTGlhV0llZzNobUJ0OGpNbGpTSnVlbjF2eDU0YkdOeGhZY0JE?= =?utf-8?B?NjYyRmlVK1dHYXQvbzRPSW55TVRiS05ybFRxZERIWWVSRTh6VVo1bW80VHRy?= =?utf-8?B?ZHR4cVpEVUtNbkJFZWJDVTYyV0d1Z3dXS2lwcGJKYjlkNllWUDVhdk9Sa1o0?= =?utf-8?B?TXJkTkFVZG0wcDNZdmE0RmR2NFRacUtjR1d4N2kySGFOMHlUbkZ5dGY3NStn?= =?utf-8?B?UFJmaC8vQTJLWk1rVmZHdUdYVGYwZGY5eTlSZi9lYVRZSGpSSmxvU2F0cGZZ?= =?utf-8?B?L0xSOXpwcngxZzlQTjZ1ZG9uSHQ3TjlrM2Vzc2JRczhsYjhYVVRKa1lqN3hG?= =?utf-8?B?YlkzaExKRjdhVUROR0JJRnhyLzU4Ny9UelhiT1R2QjNKSzNMMVJZbnRrY1dP?= =?utf-8?B?NmpuZ3Z1REx1V0xlM1NsdjlkT1RzejhDZi9Mc1dwOEwzQnBwTkZFOSt1ZnhQ?= =?utf-8?B?eDVKcnZnOVIyaDlkWWFVL1VxWE0wOXkxakxlTXpRWWlsa2ZNei9oTDZkdFU5?= =?utf-8?B?VXc1UDF6Z3p4VjNGNnAzZTd2ZFhsaHdKZUFlMHppc2ZtdkszMjAySUpMTnVu?= =?utf-8?B?UmxnQVA4WldtZXIyaEN3R2xValk0NnlDL09ORVZ1cnJHZm1sZi9qa0htaHRs?= =?utf-8?B?bmdnVG1tTVJSUXNxMFMxbWdrczlYNFI0UGk3bzlvYXBUMkxSMG96UUpvZUxP?= =?utf-8?B?cmFTWE1VWC9RWDRtU2hkbU1XT3A0RWRvVGxVTFEwdUFrYnNpNExiVnpxUXQr?= =?utf-8?B?QWFoYm15V1FtcjhFZ3VGWGpZNlBpOGdINk5NNGE5TmJnWXNXU1ZZenNXcGds?= =?utf-8?B?QitjMHN3K3FVbG42eE1nZ0xWcFMxVHhkdVcvUm1NUjlxcGY1Mm12RVNRbDcr?= =?utf-8?B?c2U2eGJmZ0lYWWJJMVJQUmlNRmZVem5hTnhSdHVPcmhyNjZyWEJoZmlmVk9D?= =?utf-8?B?ci9RdFhwQ1dhU0FlckcrSjhQQUdySWNwZGFDQjF4UjRieXpXTlNRVGlhOTNU?= =?utf-8?B?QkZFeVo0Vk9hVjEySXRYMVUrTHRBQTFuS1lVRVpBcDdHSHcxSHI2NGQweS9p?= =?utf-8?B?RGthUFJiOWwyNFVBSHRNSmVBaHgzLzRzWXcyOTlSWUlMK2I4dHhHYmY4MkNV?= =?utf-8?B?ZTQwNWZrTjhDVkNhWmtTTyswVzB3Y3JRSS9wT2Y1NG9sZUR6NVN5NW9EdlhB?= =?utf-8?B?SUFGZVFCZUV0MHRNZDhYbDk5UjFleFZYdmFYSlNTa3AvMmU2dUVBYlA2WUZp?= =?utf-8?Q?W7hI=3D?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:CH7PR03MB7860.namprd03.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(366016)(1800799024);DIR:OUT;SFP:1101; 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> > } > > > > + if ( hvm && !hap && !IS_ENABLED(CONFIG_SHADOW_PAGING) ) > > + { > > + dprintk(XENLOG_INFO, "Shadow paging requested but not available\n"); > > nit: s/requested/required/, maybe? The wording matches the rest of the messages in arch_sanitise_domain_config(). I'm not saying that makes it correct, but if we word this differently we should also change the others IMO. > Also, with this in place can't we get rid of the panic in create_dom0() that > checks an identical condition? Hm, I would possibly leave that one, as I think it's clearer for the dom0 case. Otherwise someone using a build without HAP or shadow and attempting to boot in PVH mode will get a message saying: "Shadow paging requested but not available", which is IMO less clear than getting a "Neither HAP nor Shadow available for PVH domain" error message. Just my thinking, both checks achieve the same result, but the error message in the create_dom0() instance is more helpful in the context of dom0 creation. Thanks, Roger.