Received: by 2002:a05:6a10:5bc5:0:0:0:0 with SMTP id os5csp3865448pxb; Wed, 13 Oct 2021 14:50:55 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyVLhSkSry63BQc9EYcBMAfUnHPRLx5drWDZO1N0tmXV9fsYeF3QpnlN7dzEFNfVxbBV/lq X-Received: by 2002:a05:6402:280b:: with SMTP id h11mr2981801ede.78.1634161855185; Wed, 13 Oct 2021 14:50:55 -0700 (PDT) ARC-Seal: i=2; a=rsa-sha256; t=1634161855; cv=pass; d=google.com; s=arc-20160816; b=aThO9be06uPGziceQ/OXxKBH8eeiDJRWlVA4xtSNj4jy5ptaTO/D2Zw+s7OwaWveZE zJIba8usCZAu1I/nMPQgKTIlX9xS2Sv26/sCaMcazhMS5fPFRhyjHZj6BRe6yY6TxYIv b4xFB8sZLxQfjxxFvseFXz0GBkARCmmmDge5AkU4ZD9SKhJju7a3jnIFPJdCpWN6CkW0 nfs3tfzjhFNDkiOEb7DcC//21Z5ZmDFl2iiYklXyhY2+RlB6NgN7i64Q7U/NyGHuvxiU 6Po0y1YEKaLICxjikyTiqX0fHKSZaSb1Cmj6VQQ4bdBVhSkWSLUGwPgka0Bd/XPrjde+ nkwg== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:mime-version:content-language :content-transfer-encoding:in-reply-to:user-agent:date:message-id :from:references:to:subject:cc:dkim-signature; bh=brPhOveEdFg70VeBRL29HywBAgapi912n2l4jxsh9Ak=; b=Wm6NK2RKUbdvtgdHlif5zSQ2RdGRCAQQDnAu8Xv8lOXrJiql98Be9VaipC11xu6/5v l0iiSofg4/bh/xVgWtW2DxpXChAeE5F6C7qpsq+s1C9mT/bS4CWmmKyRdVsqdDsSjP59 wLErD5DtayzUBy3oH/amMilygjWB38+Ry2WsWhOB8zeNx+Th+Ddb92FQjcQajnyc4B9q IiLITx2T6KlHG6gsXqe9O2VorErEjRzjjQldmeKSxhSX9iQ0XQxO18n/5XgGAi0FblI6 bXGzUkdjAKE3zpUmoMxMkArN+1EQY93MNU9SyR82+JhlDEUpdEtq60IDj3wOFhFhKRau 8wgw== ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@amd.com header.s=selector1 header.b=ddqjXF6r; arc=pass (i=1 spf=pass spfdomain=amd.com dkim=pass dkdomain=amd.com dmarc=pass fromdomain=amd.com); spf=pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-crypto-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=amd.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id ds12si1500465ejc.655.2021.10.13.14.49.55; Wed, 13 Oct 2021 14:50:55 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@amd.com header.s=selector1 header.b=ddqjXF6r; arc=pass (i=1 spf=pass spfdomain=amd.com dkim=pass dkdomain=amd.com dmarc=pass fromdomain=amd.com); spf=pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-crypto-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=amd.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229994AbhJMVvk (ORCPT + 99 others); Wed, 13 Oct 2021 17:51:40 -0400 Received: from mail-dm6nam12on2063.outbound.protection.outlook.com ([40.107.243.63]:18273 "EHLO NAM12-DM6-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229702AbhJMVvj (ORCPT ); Wed, 13 Oct 2021 17:51:39 -0400 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=DHhYMTqmdXOF3mb7RZZgQkem8GocpKB2O7eQDqG86Lw6Av1o0Qh+K4mcZWaMHwactktJv1wuhtJmBai01MnRBXRRNSRRi8SYtFJnc96JG2NtaHFaAzxAUDnkxfI8PzsDzossOX3whOK5Q1T7mtAJ0sFgysDTzbeoTDmqSttgB8zYfigveCbe4fjXohos7GBdIYU1L76sxXFtpZBS+JVp1Y8xJpeWpJFv6fDlZsmNEzczYAZN/ciw44rr4QfPtlyOAn2ObjnCRk0TDY84kMex4N5MFg/4nXdeqaig+RQJ6TQBNGZFANO/e4CV7R6MXdDthByd/tv0irhGZfvmG8tnlw== 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=brPhOveEdFg70VeBRL29HywBAgapi912n2l4jxsh9Ak=; b=Ma1z1aJOxJkLgcf4U67e7Y23GU5OCnx6TkPsAx8yK7LDnsrHLcDoxaMNfBicg6evzaykj/j8ORl+ba7Hyw1x9ch6zB+QlAynckbdYi3+ZL5E6bQmS9OxsfpWRq3uAcShJd6Lw7aQlMLdJLNcewywVmk6y+qQqX1a8tRfNecnWmsTiLOvcqXTA61Aie7O4jTJfhggH8s0CORmT7eKSCvNysroRtlh/+j+c9NdZhfsPXnEcCtD2NeF5keYiGlRnFFR0ct1oWX69iqlOpUs++lgVTjy7Hfe5Gvs9WDtapo0emiPKGctxxLaZLCj4c7mvUk0FjZY4mQPbmBAmHacC5HKMA== 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=brPhOveEdFg70VeBRL29HywBAgapi912n2l4jxsh9Ak=; b=ddqjXF6rO0UgL+DxnT4BnWekMsnSItIAevCdFGuqySiFa/kxojLSoskVtCp1lF0saca9uZlGdmW6j0vrFpxAOpx6rxEiUBwXqNoZ8R4lelq66qZdRXjzZ+1Gkl0zBZLoSG+UCn5tKEcQqDMJY971UPPQ/6rRkJFoIQeQkfrJqIg= Authentication-Results: linux.intel.com; dkim=none (message not signed) header.d=none;linux.intel.com; dmarc=none action=none header.from=amd.com; Received: from SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) by SN6PR12MB4750.namprd12.prod.outlook.com (2603:10b6:805:e3::25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4587.25; Wed, 13 Oct 2021 21:49:32 +0000 Received: from SN6PR12MB2718.namprd12.prod.outlook.com ([fe80::78b7:7336:d363:9be3]) by SN6PR12MB2718.namprd12.prod.outlook.com ([fe80::78b7:7336:d363:9be3%6]) with mapi id 15.20.4587.026; Wed, 13 Oct 2021 21:49:32 +0000 Cc: brijesh.singh@amd.com, x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , 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 , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH Part2 v5 39/45] KVM: SVM: Introduce ops for the post gfn map and unmap To: Sean Christopherson References: <20210820155918.7518-1-brijesh.singh@amd.com> <20210820155918.7518-40-brijesh.singh@amd.com> <94128da2-c9f7-d990-2508-5a56f6cf16e7@amd.com> From: Brijesh Singh Message-ID: Date: Wed, 13 Oct 2021 16:49:28 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-ClientProxiedBy: SN6PR2101CA0014.namprd21.prod.outlook.com (2603:10b6:805:106::24) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) MIME-Version: 1.0 Received: from Brijeshs-MacBook-Pro.local (70.112.153.56) by SN6PR2101CA0014.namprd21.prod.outlook.com (2603:10b6:805:106::24) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4628.3 via Frontend Transport; Wed, 13 Oct 2021 21:49:30 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 2b577bf6-0cde-423e-6c36-08d98e9356f0 X-MS-TrafficTypeDiagnostic: SN6PR12MB4750: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; 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:SN6PR12MB2718.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(366004)(83380400001)(66556008)(8676002)(6486002)(66946007)(966005)(31686004)(66476007)(6512007)(54906003)(44832011)(86362001)(38100700002)(2906002)(31696002)(2616005)(956004)(26005)(4326008)(6506007)(316002)(186003)(7416002)(508600001)(7406005)(5660300002)(8936002)(45080400002)(6916009)(36756003)(53546011)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?amdDZHNxYWhQUGNJRFpqT2xMWW4rVUVLYTNKZXhoVkh1K2Rod3RBTm9VaFZZ?= =?utf-8?B?VExoU2kwZVNzT3UxWkxMUTdvYW1jVGR0UkFOc0MxSzFvbGFoQ3drV2VkdGp1?= =?utf-8?B?SUlXTml6cVlFMHZaOHF4bldSeGtXcVd3NjA4M0YramF3VXRORGltVk5mUFpZ?= =?utf-8?B?NjhneTdDRkMrS2NNd3EzTlRGcENNZVVQa05XYkRFL3B3ekV2ZU03UWpNcmhi?= =?utf-8?B?TGZFWjQ4YUhVSzF6RGQybnJCTXF3UkFDanJvNjJ3aDJFYnFna2ZveWJadjFC?= =?utf-8?B?Y3A3NkdjbXN5MWhoU3ZYZGhzcFM3ajYwUHBmSnVmQVFLLzdyVnRzVmxtYTcw?= =?utf-8?B?cWRWQ1ZVaHcvUmdiek5BMGkyTXgxUFdqeGFPWFpScS82VFh4aVdia3FnK29i?= =?utf-8?B?ZTM5T1Z3SmgwTWxFN2J1QWFYVVdJZTR3bXNUR0phMDVDTTArL05jc3JlbHBt?= =?utf-8?B?QUpWWVd0Y1NEbkJqbHY2UzlaR1M3UGN4RzM5L2ZVa05YQzA3YTluNnR0M1VB?= =?utf-8?B?eWVQQVV1cGUwSkNqaDY4N05rVUdUQ0crSFJlVzNuVzltcTIrVGxqazFnYzQ0?= =?utf-8?B?RDQxUzlLakZ1VEtSWUNMd3pBOXhPTDZOSTVzYnJPQkN3WEo3ZkNGWmxnV1NQ?= =?utf-8?B?cnJIdTNYaWNjb0o1citoOXJOTzVvREQwdDI1TnR3bWdzUVVFOWIvaE5CaGg0?= =?utf-8?B?dTlrdzZHc3Rsclpzd0dURHpRWTZURmtGa0NKZ2tpdmQ3ZDZKWHdwT2pWMHBX?= =?utf-8?B?REJDUXIyZUlFYkprekg0THh4WlRiVmVEZHkrOWR6NVJjSUx5a2tzejEzeHlq?= =?utf-8?B?OHNiN2hSRUNuekNRNUhPUWZsZGdRMFI0T1huZnlpZ2NOMVBMQmtXdVo1emt6?= =?utf-8?B?WS9Ob3YvT1p4QzQ1RGt5YXpvV3l5QkE2QmUzTUIrZGI0djBsWUZ2M3ljZW5a?= =?utf-8?B?MnFpTU5DQnkzbG1raG01Sk5KNjlwRllMSE1BbUFVV1NQTXp0ZmE4cFpES3FQ?= =?utf-8?B?RFI1OWxYKzVUZkdDbGhDMXYxNEN6bmVyZHBVVElMNUlsNnd4WUt5NEs5RXlQ?= =?utf-8?B?VnpYYWUrQkYzbzB3VUQrUGsrQzNwOWF0VVF1UzlvRVVmdU9LU1pqVFRDbmw2?= =?utf-8?B?cWRtRWZIM2dESzA3Uk1hYWVRQTVFdUgzUk1NKzNkUWliQWIwbWJqK0NndHBX?= =?utf-8?B?akR3UDFsV3FuWHBrV0hWTVFRa1B5NUVZQWNWa3M2OXNqOHB6U3paeWk5Z3Fs?= =?utf-8?B?S0VXS3NYOVZ6M0Z2MGFrVjgyck5qM1ExRlY0d2JxTDA4R2NaZlhXaDdtVmZu?= =?utf-8?B?eSs0STFHcGVpaUJPQTNaM0o0b0E5Ty90VUhQYkVidGlPSXo3RDVEQXQvMWRH?= =?utf-8?B?SHlyUEZ3dkJocjlESVoyMHpPYVg5RUVtTjBTK1Iyb3NIWGRVL29XNmFCZGRn?= =?utf-8?B?TGdMekZHN0o0MFFKMWhHdzBMdlJMQ29IVHBDSjRPeEFrNXhIa2RmUU1WM1ZO?= =?utf-8?B?UkRrNVR0ZnBvelRDaEU2M2MveTB0N210VHN3RWpvVGVXc082OG5tTmZyNzAr?= =?utf-8?B?SW5Lbllqb0dBSnZnVVM5RHUrMzNQREgwcmpPc1JBMU15WVZoa2oyQzgzd2Za?= =?utf-8?B?L004SmFuSElvR1ltS05tR3lrU0N4RWhTZ0V1UGt6bHdBN3EvV0RTQXRhK3Fv?= =?utf-8?B?aWl1ZEJWa3hkbllkL0tQYzhqcG9acm0rUDREellkOG9tdE84VkZqSUJkU0NR?= =?utf-8?Q?Vkd+biKzs6m98LzVYU66KXcHDYM91R9THOFTQi3?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2b577bf6-0cde-423e-6c36-08d98e9356f0 X-MS-Exchange-CrossTenant-AuthSource: SN6PR12MB2718.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 13 Oct 2021 21:49:32.1538 (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: 53G9PMVlkiTPx6+1xFOGQ1GESEBx4l7SFxs8e0vZh2eFXHNnomgNIVHOBsxKlB0Gp4fE4WmQWCP2V/mBQpkTsg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR12MB4750 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On 10/13/21 1:10 PM, Sean Christopherson wrote: > On Wed, Oct 13, 2021, Brijesh Singh wrote: >> On 10/12/21 5:23 PM, Sean Christopherson wrote: >>> On Fri, Aug 20, 2021, Brijesh Singh wrote: >>>> When SEV-SNP is enabled in the guest VM, the guest memory pages can >>>> either be a private or shared. A write from the hypervisor goes through >>>> the RMP checks. If hardware sees that hypervisor is attempting to write >>>> to a guest private page, then it triggers an RMP violation #PF. >>>> >>>> To avoid the RMP violation, add post_{map,unmap}_gfn() ops that can be >>>> used to verify that its safe to map a given guest page. Use the SRCU to >>>> protect against the page state change for existing mapped pages. >>> SRCU isn't protecting anything. The synchronize_srcu_expedited() in the PSC code >>> forces it to wait for existing maps to go away, but it doesn't prevent new maps >>> from being created while the actual RMP updates are in-flight. Most telling is >>> that the RMP updates happen _after_ the synchronize_srcu_expedited() call. >>> >>> This also doesn't handle kvm_{read,write}_guest_cached(). >> Hmm, I thought the kvm_{read_write}_guest_cached() uses the >> copy_{to,from}_user(). Writing to the private will cause a #PF and will >> fail the copy_to_user(). Am I missing something? > Doh, right you are. I was thinking they cached the kmap, but it's just the > gpa->hva that gets cached. > >>> I can't help but note that the private memslots idea[*] would handle this gracefully, >>> e.g. the memslot lookup would fail, and any change in private memslots would >>> invalidate the cache due to a generation mismatch. >>> >>> KSM is another mess that would Just Work. >>> >>> I'm not saying that SNP should be blocked on support for unmapping guest private >>> memory, but I do think we should strongly consider focusing on that effort rather >>> than trying to fix things piecemeal throughout KVM. I don't think it's too absurd >>> to say that it might actually be faster overall. And I 100% think that having a >>> cohesive design and uABI for SNP and TDX would be hugely beneficial to KVM. >>> >>> [*] https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flkml.kernel.org%2Fr%2F20210824005248.200037-1-seanjc%40google.com&data=04%7C01%7Cbrijesh.singh%40amd.com%7C0f1a3f5f63074b60d21b08d98e857daf%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637697526304105177%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=w6xS3DcG4fcTweC5i4%2BuB4jhn3Xcj2a44BkoATVcSgQ%3D&reserved=0 >>> >>>> +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int *token) >>>> +{ >>>> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >>>> + int level; >>>> + >>>> + if (!sev_snp_guest(kvm)) >>>> + return 0; >>>> + >>>> + *token = srcu_read_lock(&sev->psc_srcu); >>>> + >>>> + /* If pfn is not added as private then fail */ >>> This comment and the pr_err() are backwards, and confused the heck out of me. >>> snp_lookup_rmpentry() returns '1' if the pfn is assigned, a.k.a. private. That >>> means this code throws an error if the page is private, i.e. requires the page >>> to be shared. Which makes sense given the use cases, it's just incredibly >>> confusing. >> Actually I followed your recommendation from the previous feedback that >> snp_lookup_rmpentry() should return 1 for the assigned page, 0 for the >> shared and -negative for invalid. I can clarify it hereĀ  again. >> >>>> + if (snp_lookup_rmpentry(pfn, &level) == 1) { >>> Any reason not to provide e.g. rmp_is_shared() and rmp_is_private() so that >>> callers don't have to care as much about the return values? The -errno/0/1 >>> semantics are all but guarantee to bite us in the rear at some point. >> If we look at the previous series, I had a macro rmp_is_assigned() for >> exactly the same purpose but the feedback was to drop those macros and >> return the state indirectly through the snp_lookup_rmpentry(). I can >> certainly add a helper rmp_is_{shared,private}() if it makes code more >> readable. > Ah rats. Bad communication on my side. I didn't intended to have non-RMP code > directly consume snp_lookup_rmpentry() for simple checks. The goal behind the > helper was to bury "struct rmpentry" so that it wasn't visible to the kernel at > large. I.e. my objection was that rmp_assigned() was looking directly at a > non-architectural struct. > > My full thought for snp_lookup_rmpentry() was that it _could_ be consumed directly > without exposing "struct rmpentry", but that simple, common use cases would provide > wrappers, e.g. > > static inline snp_is_rmp_private(...) > { > return snp_lookup_rmpentry(...) == 1; > } > > static inline snp_is_rmp_shared(...) > { > return snp_lookup_rmpentry(...) < 1; > } Yep, that what I was going to do for the helper. > > Side topic, what do you think about s/assigned/private for the "public" APIs, as > suggested/implied above? I actually like the terminology when talking specifically > about the RMP, but it doesn't fit the abstractions that tend to be used when talking > about these things in other contexts, e.g. in KVM. I can float the idea to see if docs folks is okay with the changes but generally speaking we all have been referring the assigned == private in the Linux SNP support patch. thanks