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 179D7C4332F for ; Thu, 6 Jan 2022 20:51:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244007AbiAFUvE (ORCPT ); Thu, 6 Jan 2022 15:51:04 -0500 Received: from mail-mw2nam10on2059.outbound.protection.outlook.com ([40.107.94.59]:52192 "EHLO NAM10-MW2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S243992AbiAFUvD (ORCPT ); Thu, 6 Jan 2022 15:51:03 -0500 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=TZ+pLzc8dPkE1Pry2NzOm7EHU9d2u5soMidy7cJO2ZQ7bcN/xEdhQ914LdwejbEnz22xZ7lenxPiuU9Y8KQU3xN7DMjejOTTN/xI76srbZbp7elW1pXdcUp6S4qMWFVHFbBG0wzwFc5nKdwMA63UQXxxCGkv779cc5uLdEABjnXeQyCWPzklPUZyV4LFM/z91kZ3AHHrr6dl77EhixIz0LKlto/H4wmeMBF7MBE31gWzrx5GGMVk8nUyBP/mEa8wMsnsrlqlj4zKLeazmAXzbyMHuSXDqY1BCHwbPsyZL4DKo80GV1IvTXImONJOgfUSbYn1wUpT6bSFpjePqZgw/A== 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=coqJMrBLSVlyYomoj08zUQx+rIVlaKWAofBhboH4tgc=; b=A2nPcTGrcQPzRiEEWFI6ZEpOkj1ITiFF/69MsGUw6ftSE1o0IJtLxz3CCjjV2I1MwIdy2BwkOJlk9SfxHIitqT0cllZJ01Jhr7np2ppg/FUt4iMRteho0bV6RHk/8m8vit6hKVirpzxi7bNW8v6GzpMKMJO6Qe40hLukA3SaAhZyc+iU+BtaxXi/+Yc3z+HOiycmR0oColK88ygy7R4AgP9dwbjD+Gu7t/uWRcMMz/XQ/O9hfLSmKG93AGAGBCQcHNBYCb9cTzjLMtpwawa6pp1DuiYgCWKFSpHn2eg1YTso6Qnadb0ur8RXsIJE/R6s7MQnWdUlue5X+hdXQA5w4g== 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=coqJMrBLSVlyYomoj08zUQx+rIVlaKWAofBhboH4tgc=; b=rmA1fkE7S467QUwn9YZivkFBmkkefUAI+0JqP+uJ7PeMkUlSp+sm22bv/ztgTpeY7iq7iilchcsgeNtJsIK5p7jje8Ayj8/OH9XDuUcPZdghec+EijtiDrwlUpIP89qiu9RHZtdveM/PFWZLrlwCFXaf58C8VZPVF5/+Ax4z3TI= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from DM4PR12MB5229.namprd12.prod.outlook.com (2603:10b6:5:398::12) by DM4PR12MB5247.namprd12.prod.outlook.com (2603:10b6:5:39b::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4844.13; Thu, 6 Jan 2022 20:51:00 +0000 Received: from DM4PR12MB5229.namprd12.prod.outlook.com ([fe80::ccd7:e520:c726:d0b]) by DM4PR12MB5229.namprd12.prod.outlook.com ([fe80::ccd7:e520:c726:d0b%5]) with mapi id 15.20.4867.010; Thu, 6 Jan 2022 20:51:00 +0000 Subject: Re: [PATCH v8 13/40] x86/kernel: Make the bss.decrypted section shared in RMP table To: Venu Busireddy Cc: Brijesh Singh , Dave Hansen , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , "Dr . David Alan Gilbert" , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com References: <20211210154332.11526-1-brijesh.singh@amd.com> <20211210154332.11526-14-brijesh.singh@amd.com> <18eadf9d-8e31-0945-ccf4-2cb72b8e0dd4@amd.com> <444b6c78-c4d3-f49c-6579-bd28ae32ca3c@amd.com> From: Tom Lendacky Message-ID: <4c1067c7-a85f-79fe-38a8-2f68a94a358a@amd.com> Date: Thu, 6 Jan 2022 14:50:56 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-ClientProxiedBy: CH0PR03CA0006.namprd03.prod.outlook.com (2603:10b6:610:b0::11) To DM4PR12MB5229.namprd12.prod.outlook.com (2603:10b6:5:398::12) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 2232576a-d440-4832-8c11-08d9d1563f0f X-MS-TrafficTypeDiagnostic: DM4PR12MB5247:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8882; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: mO9bNiWihNDXTZqksmJyqityQPTcW9e4xHIta8DetpEUC9zyg0RtfPgeYH6OE1v0wO2no2aXoP9lc2Q6m4Wup3l22QOWNWXVxmdOBYvggwlENpClh9CkWvqQJLl/TT3qtG9Net/NbbuaDdMXOdetmkagPpRr0GOLqNEE0qQ8d85clPblLHqyRGc+1cbgTYTkRFIjP0bJcC3omg+aGQ4DfQf3yPWeElhdTfIHGaN1LlAKJuf2vXoYBCh3T4TlcQbgQOWobtAtCjHhAylJpFgelvCAB/d74RCC6AE9h/kiY3DnoZBQQVRTqqqgWdfm+LEAyZJWZ5no1CYqd955g6OUAEI+2ogNu4xr9VnjpmNUYHwHovQcpwe/5otDU5pkbB8bF4NucFNzgLM+g6fIohs3E6saL+DJ30RUkvwYEmcOAwycOmaUyXSKubQ0a+uabotgtkbiN+dG6/MFi222w9sWrjE/z24eVojKawSTTpZkLMiNjVodq+LREeoPhXt57KJAp8vvQV3WZhMTtafDwRbcrFont+MAXge0NJz+hKCAmneDkAFa8nM3tBJp10zBwMu5YSi96/0nInJaRbPvSSRg7HTICxY4qvnXiG+nJzp0xri03Z713vdIEAHlHygJRPrezcphBkX8X1c7LVNzas+5+xXpwTZBFHtPrXZa43ToDk7HY6eN8YwET6Ak/ycEGKpAvDJe18Si83Tq725wEQCo39TOIeIfD9HMWNp0F0dwjDh6AyY87pPttITJho4Md1se X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:DM4PR12MB5229.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(2906002)(38100700002)(8676002)(186003)(4326008)(5660300002)(86362001)(6512007)(2616005)(8936002)(54906003)(66946007)(36756003)(31696002)(83380400001)(6916009)(26005)(53546011)(316002)(31686004)(66556008)(7406005)(7416002)(508600001)(6666004)(66476007)(6486002)(6506007)(45980500001)(43740500002);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?eVVybjRlVENtRHMzL1ZzdWIrRVFMRjlBOGpyOVVJNXVQVEZHTFlDbXl0NW9i?= =?utf-8?B?ZnhlL1FlL0lrNUdqWGlqdnVid1VCRFc5aFdFVTJvZmpKenBlTEN0QzdGUUZZ?= =?utf-8?B?YTk2bjAxelBXbS9hK2k2YnE3ZmJiRVZFR2pYVjA3WXF1WksxaDh6SW1BeHlK?= =?utf-8?B?VllDSkZBaUw3YVpBRVJzOW0zdi9jaXBhcE5zNUZRcTd4TXdPd0Q2WnVPclBS?= =?utf-8?B?RXZSU2hiZ2NQMkRldGpkVitZWkVNVk1oWVh5djcvYzBIQ3A3c1RrZkIwUWpy?= =?utf-8?B?MGZSeGdOU0dGbWdpbTdyTEhRdWpzbTRUV25PZ0dCdkczZTBoN2ZRS0YrdGJj?= =?utf-8?B?WmRVV05HeVdOc2FkNi9HbzR6ZkRzdWJndWUrUWJRc1hzd01NUHVMeTBjU2p6?= =?utf-8?B?YmJIUjVhNWV2SW8wSVBqY2VrMEJNaEtpVHYxMTN6RENkRC9mQXUvL2J5UzdK?= =?utf-8?B?N25GaUlqZ21FYi9BOTQyN1B0alNJcXZoK1Fpd05Ma2FZK1ZlSU9lSCs3YkFW?= =?utf-8?B?SFdTYlExYTlhSDhZK3M1NGlENDB6Q0tmcDFtUjVEWDJLbFdqaUk0SjNKMllJ?= =?utf-8?B?cmViM1FpMTdRL0QvM3craFM0d1lLcW4wcXJrQWtOMDVYT2RER3hpOHJxcXhF?= =?utf-8?B?SExIRExkVGZvTExsRCtac2h1YkdSbkZLcHNnY2dhdWlqNGJRTlNwRStaV3F3?= =?utf-8?B?alJJNFZyOUpQdlBzaSt3Slc1aXNOY3JFRzVodlJNdDVJdVJSdTBNNjJhdVNo?= =?utf-8?B?N3grYmNJa2xNblNuYlQvRkI3OHNIMGQ5VzYycXcxcmlNc0IwUVFvNEJSKzRh?= =?utf-8?B?YTcxdXVKR01RS1dwcDdnQVZ2NlM2YzZTM2xRSzZMYnNvcTN3SkhoTHNGbnFs?= =?utf-8?B?Y0tIclBIbzRtZms3SHZldkVVSXM2NEp1Sm9SSzVQL3kvRnRRVExKZ2tidEdw?= =?utf-8?B?UzhsbDhIbUtseDc5NWEvRTRlKy9lRjd0TDV5bzVmRDlvQ3d6NUFNcWpBZjRV?= =?utf-8?B?bm9jMWlXaEZxVVRGR0p1bE5DOEZlWldFaGFBSnRJUnhPSFZzbTYvN0QrdVo4?= =?utf-8?B?b3VyQktpNW1hTmZHU0dNaDRPa3RqM0w0VWU0dVI5THNxd3BHanBJcXNHRGtn?= =?utf-8?B?RTUxVGp4WXJNeUV4UllnbnFTUGhRdkxvUVhBMVJVV1ZKTDUrOXNuRnd4SmdL?= =?utf-8?B?bVRhbWJsbVgwVlV4TWRSL0JSRW4vZTcwKzZUaWV5WTdjR0ZPQnBXL2dTOW5s?= =?utf-8?B?cVAwelFNcFFFVkhCczNPT3NRbUVwaFJXQ0xFY09jVThvR1VRcWhWbzZNamlP?= =?utf-8?B?Mi9OY1AzbWpUSHFMek9US2JHNzNIS3dUeCtiSlMzazVCZDF2WitucEt4d3FR?= =?utf-8?B?bE5KRmI1NFRoYlhDYU9aOURwVk5jcGJWQTJkQXFlWUxhcys5enpPVVYrS1p0?= =?utf-8?B?cUpCRGpnOW1VOGxDczJtVjdUejNETGVPSS9DMjNuQkpkTVpIMisyUTRXSTFm?= =?utf-8?B?ZFIxdGZRR2JYeWlKd0JqNTVZRU9uMHF4R0NZT0YyOVVzSlJOaDVrMnRDekx2?= =?utf-8?B?T2hKSEJIdGxQWGF5SEIyakY5bElLNGdKTmlaczN2akRiYkRZYU8rbi9qKzIr?= =?utf-8?B?bXVBVVVqWWJRd2t6Mm8ySjFYL2dVSG9zbGZHOG5oRDQvL3F1emEyNU1ESkxL?= =?utf-8?B?S0FUWFZ1eVdUenpNVk9ua2VEQ2pvVnl6WW1mejRZUnpwekhxZ1FKTVVJK1pz?= =?utf-8?B?YnRkV2g1RnFBcGI1VTVhK2FySlRTUnFxZDBVbzgvSXlaRk91bVdudkQxTURF?= =?utf-8?B?ZEJGeStBSVRldE11U0FtY3hhU3JNWkpzVUNocnNHQlpSM3F6c05Sd0pNTjZT?= =?utf-8?B?NndxLzlzbE1UR0tRVThac1JJUDg2bWRKYmlCak16M29rYlYyTTllN2E0ODY2?= =?utf-8?B?NlJ6SjcvR1lSalArZWx5N1ZSb3dWaGkxekZySWVwb2JWNWxxcWIwaFlYalVT?= =?utf-8?B?L0JsWTVpcmplSy84QjVLcllKbFpjb1Q5TG9aZjRZQWNaTEdaUXF4YmJGditT?= =?utf-8?B?MzZwampLdFdaQ016cVlZdUV4eU9aUFlvazNhaXBDUjczK2U0bThiTEN3L0Fm?= =?utf-8?B?WDdNbFAveitXRUQxMGcyNGZsRGtGeHdjOU51TVBURzgrbWpEcTRTQlFnTXVY?= =?utf-8?Q?SihKnaCAJULa09ALyTGvpy4=3D?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2232576a-d440-4832-8c11-08d9d1563f0f X-MS-Exchange-CrossTenant-AuthSource: DM4PR12MB5229.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Jan 2022 20:51:00.6730 (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: 26eYZljRejg1wzq2R1hYQDqrfTLxj89YZ4DWrUINsD7c0lE4KCi8XpCFyB/aI3NyX51yiUXKcWCjYgVAKorbIQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5247 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 1/6/22 2:16 PM, Venu Busireddy wrote: > On 2022-01-06 13:06:13 -0600, Tom Lendacky wrote: >> On 1/6/22 11:40 AM, Venu Busireddy wrote: >>> On 2022-01-05 15:39:22 -0600, Brijesh Singh wrote: >>>> >>>> >>>> On 1/5/22 2:27 PM, Dave Hansen wrote: >>>>> On 1/5/22 11:52, Brijesh Singh wrote: >>>>>>>>           for (; vaddr < vaddr_end; vaddr += PMD_SIZE) { >>>>>>>> +            /* >>>>>>>> +             * When SEV-SNP is active then transition the >>>>>>>> page to shared in the RMP >>>>>>>> +             * table so that it is consistent with the page >>>>>>>> table attribute change. >>>>>>>> +             */ >>>>>>>> +            early_snp_set_memory_shared(__pa(vaddr), >>>>>>>> __pa(vaddr), PTRS_PER_PMD); >>>>>>> >>>>>>> Shouldn't the first argument be vaddr as below? >>>>>> >>>>>> Nope, sme_postprocess_startup() is called while we are fixing the >>>>>> initial page table and running with identity mapping (so va == pa). >>>>> >>>>> I'm not sure I've ever seen a line of code that wanted a comment so badly. >>>> >>>> The early_snp_set_memory_shared() call the PVALIDATE instruction to clear >>>> the validated bit from the BSS region. The PVALIDATE instruction needs a >>>> virtual address, so we need to use the identity mapped virtual address so >>>> that PVALIDATE can clear the validated bit. I will add more comments to >>>> clarify it. >>> >>> Looking forward to see your final comments explaining this. I can't >>> still follow why, when PVALIDATE needs the virtual address, we are doing >>> a __pa() on the vaddr. >> >> It's because of the phase of booting that the kernel is in. At this point, >> the kernel is running in identity mapped mode (VA == PA). The >> __start_bss_decrypted address is a regular kernel address, e.g. for the >> kernel I'm on it is 0xffffffffa7600000. Since the PVALIDATE instruction >> requires a valid virtual address, the code needs to perform a __pa() against >> __start_bss_decrypted to get the identity mapped virtual address that is >> currently in place. > > Perhaps my confusion stems from the fact that __pa(x) is defined either > as "((unsigned long ) (x))" (for the cases where paddr and vaddr are > same), or as "__phys_addr((unsigned long )(x))", where a vaddr needs to > be converted to a paddr. If the paddr and vaddr are same in our case, > what exactly is the _pa(vaddr) doing to the vaddr? But they are not the same and the head64.c file is compiled without defining a value for __pa(), so __pa() is __phys_addr((unsigned long)(x)). The virtual address value of __start_bss_decrypted, for me, is 0xffffffffa7600000, and that does not equal the physical address (take a look at your /proc/kallsyms). However, since the code is running identity mapped and with a page table without kernel virtual addresses, it cannot use that value. It needs to convert that value to the identity mapped virtual address and that is done using __pa(). Only after using __pa() on __start_bss_decrypted, do you get a virtual address that maps to and is equal to the physical address. You may want to step through the boot code using KVM to see what the environment is and why things are done the way they are. Thanks, Tom > > Venu >