From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM02-DM3-obe.outbound.protection.outlook.com (mail-dm3nam02on2062.outbound.protection.outlook.com [40.107.95.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20528227EA4; Mon, 2 Jun 2025 20:32:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=40.107.95.62 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748896358; cv=fail; b=IyB4yKuRqYhtAWB2N7l36VhMMRioEnlz/zUDE4CExX+IhqFVQHi7JsbSuZe8lg/IbBbkzBwfDi6w+SPnArf9PU0kYXQZuS0d8uQbb2UZufcSTwg2Fg5oVW873XDIQA+5fG1O1nEu0vG8+4VrmiACTHkFIkRAP94qIaN5iJ46gZc= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748896358; c=relaxed/simple; bh=nM90/0q7j2DedUthyWkDmszvtrwi9XCKu9OVLtsGpZc=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=MmBxQp+zCY6blPT3xO9kLbH/FC75KaCIjp5pyIkCL1La1wD4WALUf7yM2nkZy3CNTGtYJBDt3fjbB3xatLRIn1t/b+/XryFrhvCpK2Z69rgYQBROev2ij7mRR1vf4NX0iEeLl4ZgyysDnqnj7zpq4eLgAo41xditMZMyiY/sPNM= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=PvxPjov1; arc=fail smtp.client-ip=40.107.95.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="PvxPjov1" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=OZOe5RE8G7zgEjkZTAQTQf/ItN4pDE85uOOeD5SFNsFZZ+VYtVlngMxYT4lciLSmsz1sNeaN9fsn6wUHnxoJc4S9/7CyJPJafQ2aQ/A3pZEW1R+fwGxrjnpv+I2+RYqxe+x7EpxxWJwlEfMPlPIMbd48WpmFjrCfLZN3GPBtvoa2+XzfsqaGMT7OY+gx3bmGwEAH6dvNtH/s6iShF5d6xOHI/JOigbYPEDj9/61KivMjnVfgZsdBTJdjQhqRwRNNBIakIsOipqbsOZoDhVSlcMY+MERhExnOyTZz5ZLyTA+djKlBhSxgJvW3cRaOUnunCtrg7FLQblBaz9xq5Pbeyw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; 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=3Xu3FwXUtD/eKOclE2aUJTZagtV6rwmIegAIAvdErJg=; b=hlnPd6hwz/dFAHRcLcpoGSxMXZmDFGMDjpFupQVcmfXRBfAwuxPKMluf1DJZblot216F+dqks37zGs5o/jERHoU5FgPGxIqQHV79pxe5UznSFnAz6evHAmf7mWtN3V68gGdUgzgmpsxSRHw0vv+bG3zjhVX+qlLL3w2SATtNRxqXefKUB2mQI1VTe5IA7ybq2TQ8+tuEcSs/NmVuii4t4S03lIq5dj/pYAH48Fc2f7Rxc23lTUDlqVMnNkt7jNiCVDuo/D6NUlRWhpVUksTUenCD6hH6sjedlC4QYxg7m2JJKhVNZB047xKzLVzD9Wg/xPHM7RT+E7Fo7O5OVbNGXw== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=3Xu3FwXUtD/eKOclE2aUJTZagtV6rwmIegAIAvdErJg=; b=PvxPjov1WTdn5pjfkb6Yr8X6jA39VV0i1+rG6l46t8HPo/sVB4zCdoqOSu/KdWBvlvCoOam0jwyWS/ICaSeg6FE1QKee0EqTPXKxvch98aJnfarBex0AvdnKyGEsdZAF1aBbsT5H6m40auWq74lBxysi+63sjeOtWH+4mxhQszc= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DM4PR12MB9070.namprd12.prod.outlook.com (2603:10b6:8:bc::12) by CYYPR12MB9014.namprd12.prod.outlook.com (2603:10b6:930:bf::16) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8769.36; Mon, 2 Jun 2025 20:32:34 +0000 Received: from DM4PR12MB9070.namprd12.prod.outlook.com ([fe80::44d1:2c2f:297a:591b]) by DM4PR12MB9070.namprd12.prod.outlook.com ([fe80::44d1:2c2f:297a:591b%4]) with mapi id 15.20.8769.037; Mon, 2 Jun 2025 20:32:34 +0000 Message-ID: <6532fa2e-53e7-454f-80a6-c88b70182a6e@amd.com> Date: Mon, 2 Jun 2025 15:32:31 -0500 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 5/5] KVM: SEV: Add SEV-SNP CipherTextHiding support To: Dave Hansen , corbet@lwn.net, seanjc@google.com, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, herbert@gondor.apana.org.au, akpm@linux-foundation.org, paulmck@kernel.org, rostedt@goodmis.org Cc: x86@kernel.org, thuth@redhat.com, ardb@kernel.org, gregkh@linuxfoundation.org, john.allen@amd.com, davem@davemloft.net, thomas.lendacky@amd.com, michael.roth@amd.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org References: Content-Language: en-US From: "Kalra, Ashish" In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: CH0PR04CA0062.namprd04.prod.outlook.com (2603:10b6:610:74::7) To DM4PR12MB9070.namprd12.prod.outlook.com (2603:10b6:8:bc::12) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DM4PR12MB9070:EE_|CYYPR12MB9014:EE_ X-MS-Office365-Filtering-Correlation-Id: a9056735-dacb-4a86-3633-08dda2149b21 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|7416014|376014|1800799024|366016|921020; X-Microsoft-Antispam-Message-Info: =?utf-8?B?eVNWNFBYc2R6RGFpY0RPTmo0SFQ0K0NqYlVmaTB1Nnd4OVdjNDgzdW00am41?= =?utf-8?B?MEl6SnhZUXpCdHUycGI2aHNIT3JEdGVnclQyUSt0dWxCb0hBcDFUNU0xNG1w?= =?utf-8?B?bHBQNUZJSUMzcG54dGtDb2FsaFZZK1JpQ3lMc0l6UU01T2diT2xvMVlZR3ZQ?= =?utf-8?B?dUtFeUFhbSs3d05YdjFML3J0S2ltb1lXd2h3R2NjUXRxSk12Y1dCKzhxa2ZZ?= =?utf-8?B?eVhqdWJvci9YN25IUTh5OUpDbmlpVUV4SnJOc3VTY3JKdHlNc2xJby9UY3Fq?= =?utf-8?B?Ym1qVkgwZzNKempVQ0N1K2RzTnhQcGhDYjBZeXMybTlkZGF6Sk1jR0VGSy9H?= =?utf-8?B?UXNBWlp5cVpWUG9tbXpvTldzZ3Q2anNyRXBHSi81KzVlUGpPZzR2TlY0NEhs?= =?utf-8?B?ajhwb05Kby9qTlBUUTRVWVAwbHFZSjA4Z0RxN3FPUHBGeCtZVVUxdnlPZk5o?= =?utf-8?B?YVNsYXZJTHptQk85M1lpdmRPUThhVmt0S2VBSlhDVitPdTlsMithZVhjYUhw?= =?utf-8?B?VEFxZ2RnWWNrMW5FaTluemFQdUlOUXhkS05LMitVWWdRM3JHZUQ4dm1JUnQ2?= =?utf-8?B?bnFoZ2MrSEZERDg5NnZqSHZ3VjBycFdZMXN3WjdlUmVDRTVmN2EwMXNCR3dT?= =?utf-8?B?bzN0RTN0eldzMTNlVnZPT3kzQTF5WWtENFVrT3J0alNua25reGRUODJ2aWhL?= =?utf-8?B?ZXg4YjREYUErbGNOYmFhd2ZWa2hUNW5BSHNTSGZGa1FTSnArVGpYVWNTNlUz?= =?utf-8?B?RjlnbWJqRW1IakdRRkQzbXBMWEF6TWZaNnNac0dKcVIxbTlJUmtYNEdUVVoz?= =?utf-8?B?anppc0xoZ1dZL1JMS2lZRW8vd0UwSnhMZXdhbUVjTHZKakF6SmhReUF1anBZ?= =?utf-8?B?ZTJJS0h5ZGxwL2FiVXpNd2EvZ1Z4R2JXYjdFTk9aY09uME9WQ0hJaWZ5QWNJ?= =?utf-8?B?Ukw0MVJJcVNPUHExNXNTQ3dTS3J6QW1PUmRTa3g4RUZjd1FsK2hDdjFmNWRU?= =?utf-8?B?VmlndEZ6Q01mT0xOVVRoRGM0VUNlRFNMQk1ITzJkZGRVeG9GeXFKQXQ4T2JN?= =?utf-8?B?SjI2SjlHeVBlM2pvRW83OUNnZDRkamdwWThqa01DUGJnSGxqWFJpcEYwWGJJ?= =?utf-8?B?ZURqTG5vUkRiTzRzK1RYcWttczFoRlJqM0tsTnpkUmVtZm5wWlVydHNreEVP?= =?utf-8?B?WEQ5dE9tM0hSS2dXZE9NOENZV0xGZ3lMYlFzbXRsNmloYVo3WGtPN1UxWHdp?= =?utf-8?B?TE5oV3Z4aHpsK1Y1ZEZWQW8xWjZicVkweFJVRlFqOTFwUkxzQ1lsNFl2a0pC?= =?utf-8?B?S1F4U0tKUlF1dzBqMTk4aEdtTzQwYVRKRU94M0I2MlhLNXE2eU1CeE5BRkxx?= =?utf-8?B?WUZOTCt6NWQzYWVPaFcxRm5VcnRVL0xSK2w0SHlvMHV2clVDeElqakJuOEp4?= =?utf-8?B?clYrOUFLR0pJS3FNVGpQbHlxQjA5MXNWS3NRWDQ4K2dXR1RtU200K0JXQUI2?= =?utf-8?B?Vi9kdGppaHAvZDdjMjFlZXZ6OGFpbmdXRjVaY1E1RWdiYXFoajZESnordExW?= =?utf-8?B?UEppd0lSZnYxU0VxUG9GNnFpcGpNTElTOTBlcno4T0tEVW9UOUt2VzVjSlVZ?= =?utf-8?B?OVk5OE0yZXVUbmtyNTFsOVdQM2taNEZzRCtINHJzMFYzK2piL2lNd05PcUlP?= =?utf-8?B?U1BkbnBDdFBHTGcrdzZHK3FYKzgrTnJzK240VDI5cXdDUUFQTE04Qm5KQnZB?= =?utf-8?B?ejdGTUQ4bWdGS3RlWlNEcXpHaXdKblpGc3RidGkyakRiZTJ4U1hGOXJsbFcw?= =?utf-8?B?MUtrWU5FVzZxVWh0S2Qrc2dnNXhlVmpHS3cvU0ZqaUhKUXEyWmRsMzNrRmlu?= =?utf-8?B?Ym1QL2JYT0FwanozeUZGNHlwbXZyZHJGWGtENnJOUGljaVNSNW96ckQwN3J5?= =?utf-8?B?MnlMTE5OZ3EyWkNibFZCUFdRVnVPK2hyeTI5QzlGS3k5ckxZOWRrS3RHZVly?= =?utf-8?B?TWxSTzZnblNnPT0=?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM4PR12MB9070.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(7416014)(376014)(1800799024)(366016)(921020);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?UFovSFhNaitGSFpEN0psV1BuYnJNT0VWZHJlRThWd2lFaG9lUUVPL1JIY1BQ?= =?utf-8?B?b0Q2VnNEaENmdjFudDc4cDIxdXhIeU9JQkFJaWV4bzkvQlJmelA4bFBWaG53?= =?utf-8?B?TVEyb0NHQ2lsZWl4dmJrV1FIYnU2NDdWenFXUkFmL2N3R2lJOFk1em43cVNM?= =?utf-8?B?aUQ3akNVSFQ5T2JVT2wwL29UZHpERzkyWEt5Qm1kZ3ZSZUJucktmRHRhbDBL?= =?utf-8?B?V1k2TEE4c05iSXB4TlptMVgvMHZYM3hNOWFlV0RKTGRZdlM2bjBsOTdvWVlG?= =?utf-8?B?RDNkNDQ0eUFFTmE0azN0K08wMG1RL2pWbHcwWHJBODVsRmIyWXZUcE4rbzZE?= =?utf-8?B?MHZobFVNeWE4cXBEdFZQWXk3dEgwVG5EZ2YvMHZjL0lsNURhSXZsQWhjQ1hB?= =?utf-8?B?a1FrT1dzK1VGeHBkOWJ6aER2WU9aZDFUYTBwZ2c5eEdGQ1VxRnc2UnJaY29k?= =?utf-8?B?RExMUHp1MGVZMEFRaEx6bDFnNnlabDIwb2h4OW5zQjAyVGYxMy9hQnpmNTl4?= =?utf-8?B?RE1ZTzhRQzEwdTJ4emRvWi9Vb0dvMzBreGVRb3g0Q2pibThwdm1tS1hyL2cx?= =?utf-8?B?ZDI4NTIxV3cwR3dxMlcxcW54dXh4UlJKYVlUQjN2UFFJS3hZWDMvRWczMzFi?= =?utf-8?B?RlMyKzFEaGdRT3pxOWxFdmVuTFdXUWIwQkt2N1pCbUhsTVVjUnJBU1Urc2wy?= =?utf-8?B?TjNIQnovSlhzbjZkOXZoekV3Wk5MaWJOY1ZwMEYxT1ZOYU1WQjhBZi9kNXlU?= =?utf-8?B?ai9Pem05dm53a3FIUHo2cGdTMCtIK0VhSnVYYW50Szh5M2hYVE5yWHBHb0VU?= =?utf-8?B?QzJBVXdjN0g2TmxQbGIzQ0ZWa3JZYVBRelpZZ0xIMmtqY3M1dm9UN1F3dnRx?= =?utf-8?B?SWN4Q1FXOWRIdFVhOE90UVNMSTFFZ3lPc3dpVkJxUG9jblZtMkhxSjVua2RX?= =?utf-8?B?MnoyY3BLdUpGZlpWUnJsUGxrTnVrcEowaGtOZWtTdEpFQ0h1QVhDQk1yV3Uy?= =?utf-8?B?QStYN25kdUNESmsvcUwxVVBGdEVUU3EyWnE1OXVFMmF2T0hMRjRTb1M2SWVJ?= =?utf-8?B?NTNmVlNBMjBUTHM4ZmwvbXJ2c25yQi8xd1JnNnFHUW5sUGtVOVdUeW9MME4r?= =?utf-8?B?WGVhc3RIazRBTDlZMzNBYmdzQXljZUx1REpvK1FpUnBIakM5bFN4SDRWWHhh?= =?utf-8?B?OEIycVJzOEhpVnZKSnpibjE5Wi81clFIR281SnNTRWlxd3hHeHlBZElBVW14?= =?utf-8?B?TnUxakVYbVdhQ0NIWlJmQi9kcHFwL0k3WUQ5M0wwR0t4a25tTCtXZ2hrSjgv?= =?utf-8?B?OXpSNjhHK3NVZitMM2hENUNSVi9jRmp3Wk5XQTdTR3FvWFpkUTl0eThJUFhl?= =?utf-8?B?K3IraVhkdngwL3dNSHhLSTdudjRxUVg0c3hCczRBZzlOT1cwTzA2RTlsbnpS?= =?utf-8?B?blB2UnlHby9xNUpHTnU0aEgxMUhzT2g5SU14VEhFcis2b1p1ZmdEVllYRkQx?= =?utf-8?B?cGhqZC81N3Z6U1ViWmdMaUFlTGMyMDFxcHpGL29URFNFekVuTUxuSlkxU3lX?= =?utf-8?B?NDk1OTdSTzhMUlUwM1VzUTl1VTd2N0YxQk5FYzQ1eGFaT1ZiTjVTcDd5MXpI?= =?utf-8?B?NXcxZ0dGZ1NPOXBlNk4yK1B0ZEdoWWk4T1JpcGVHOFE0RGxrYlI0aEZKRTh2?= =?utf-8?B?UUZxNXc5a2FxcTBQZGl0OFM5OVlwbHlTT0VzMUFTRjZhZVMvaFhuTHh4dXV3?= =?utf-8?B?M2lDU3k5NVkydnp2dkM5UnVBanpuQ003RlhQQ0NtVEJaa3NpN09kc2Y0ZnRv?= =?utf-8?B?cGg4dGdCQXQ4VkhoL3pMWnhISlpHaTRNSDFWdXJsekVYYXZuZHVNNkh6KzFL?= =?utf-8?B?b3M2VjJnZXBzNm1pdjdjREpPY3lFbXRSV0Vkb1VzcEo3QW9BRFdPVTlxbWZP?= =?utf-8?B?YmJ1anFwVW44SCtaZkFkcEI5ZkljM1lockpyQ1VQM3lMTmE2VDVCY2g5aEhE?= =?utf-8?B?Tm80S3pZeVE3ZlVTV2V4QUJkdzlvaFhVaGJsNEpML3cvWTJyVVRrVElCV3Ur?= =?utf-8?B?K3NIMGU1UjBqL0E5QVc0dTBMK2R3em9IOVJHRTdSMEJjbFJzK203VkVMQlRy?= =?utf-8?Q?+rSsbQybAe44YZYeFbSjkfBcW?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: a9056735-dacb-4a86-3633-08dda2149b21 X-MS-Exchange-CrossTenant-AuthSource: DM4PR12MB9070.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 02 Jun 2025 20:32:34.4110 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: wv5Ns00veorSsmYHkgNuWEqK9DbmFkjX/FwiHaZKVfZ8td50X6gGhT3NdYwzxkpDZa0mrmvRpj7xMbm3VIJfeQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: CYYPR12MB9014 On 5/23/2025 12:29 PM, Dave Hansen wrote: > On 5/19/25 17:02, Ashish Kalra wrote: >> + kvm-amd.ciphertext_hiding_nr_asids= >> + [KVM,AMD] Enables SEV-SNP CipherTextHiding feature and >> + controls show many ASIDs are available for SEV-SNP guests. >> + The ASID space is basically split into legacy SEV and >> + SEV-ES+. CipherTextHiding feature further splits the >> + SEV-ES+ ASID space into SEV-ES and SEV-SNP. >> + If the value is -1, then it is used as an auto flag >> + and splits the ASID space equally between SEV-ES and >> + SEV-SNP ASIDs. > > This help text isn't great. > > It doesn't come out and say what the connection between CipherTextHiding > and SEV-ES+. It's also impossible to choose a good number without > knowing how large the ASID space is in the first place. > > Why use "-1"? Why not just take "auto" as a parameter? > > It also needs to say what CipherTextHiding is in the first place and be > more clear about what the tradeoffs are from enabling this. > > Sure, i will work on improving the documentation. Sean, looking forward to your review and feedback on these patch-series, especially the KVM side of patches. Thanks, Ashish