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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MSGID_FROM_MTA_HEADER,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8E123C4361A for ; Fri, 4 Dec 2020 17:18:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 454B522B40 for ; Fri, 4 Dec 2020 17:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731017AbgLDRRn (ORCPT ); Fri, 4 Dec 2020 12:17:43 -0500 Received: from mail-dm6nam08on2049.outbound.protection.outlook.com ([40.107.102.49]:37857 "EHLO NAM04-DM6-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730547AbgLDRRn (ORCPT ); Fri, 4 Dec 2020 12:17:43 -0500 ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=VGICusjk+NZkiYrVTttXfPZXnB0TyUzzqoMSsV64N7Y5A3/n3Tspv4WVw1owlerhrAi6lwaHIMIkGuvP/Jb5eJF/u9/EGSGlR7Ui4ccffH7D87oow/uZYRN1yJHjOs9xn7z9eo79+NXQk7npuj/ccfnDgL0TNCvQFcM/z2YSSJGbCgORY7AcV+UKS/N1z0E/S7F9V331hgJJbhwasY0OT7uGAAUtXjD+n17tHov+z+4wHLRP5AmB2tREQjc8IGw8fPbgp2X/XlD1CTFThMrh7kX0nrRT/bVhT8I7SK6ZXi8iu3k7QQh4tako3n6I/alCpkAyZ7agi1klqj7Ylk5t/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-SenderADCheck; bh=UA9TlqmEy5WvXZBr0/9JmE4RXmdril9wkWatqr8z+n4=; b=njjaiUnCS/zm2UVPi7ITgO+UfE3PLnrk+d+jJly1XNM3mmwiqpUo2kelMc0hpUM8H0W2D9wWiKGIi7co0wdsLOMZIKU5bFcGByxS6HzY3wzCi/XZ8qry/hSwLw5cZsDY7AC17/6c768f3x8R46jfavo/u+KLpOBs7THBVrW7QOIVUp6whSWXzCITgZcrQ6Y/7RLivozetggtG2BUxUhhlwF4rDPh2ueUzorku510jjzdJrF6vxWQ27VgcEKrAV+ow4mBwWVFDkR4270KX+fRlExAEMDO1C0WdHDBd5ZzErj36RCmHgo0s1fX4DwFIFmgrcTewoBZI+9umfqwNilaEg== 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=amdcloud.onmicrosoft.com; s=selector2-amdcloud-onmicrosoft-com; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=UA9TlqmEy5WvXZBr0/9JmE4RXmdril9wkWatqr8z+n4=; b=To7kOzgztyDG3GKED4gFTqSXwU/cajO5QG/JjMaOYuVTvV0YiAf8+4aofDXfLandHQFMYJZc8iexczfJ6K8BilgD8H8O1AbukrP94pYXT6oIS2n/l2891kD8Zmc/3XJDBAXdWbGsdExfPayJu5BbfUbuDlwa6zMNrIuiZ7aBJDM= Authentication-Results: redhat.com; dkim=none (message not signed) header.d=none;redhat.com; dmarc=none action=none header.from=amd.com; Received: from SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) by SN1PR12MB2366.namprd12.prod.outlook.com (2603:10b6:802:25::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3564.28; Fri, 4 Dec 2020 17:16:50 +0000 Received: from SN6PR12MB2718.namprd12.prod.outlook.com ([fe80::18a2:699:70b3:2b8a]) by SN6PR12MB2718.namprd12.prod.outlook.com ([fe80::18a2:699:70b3:2b8a%6]) with mapi id 15.20.3632.021; Fri, 4 Dec 2020 17:16:50 +0000 Cc: brijesh.singh@amd.com, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, joro@8bytes.org, bp@suse.de, thomas.lendacky@amd.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, srutherford@google.com, dovmurik@linux.vnet.ibm.com, tobin@ibm.com, jejb@linux.ibm.com, frankeh@us.ibm.com, dgilbert@redhat.com Subject: Re: [PATCH v2 1/9] KVM: x86: Add AMD SEV specific Hypercall3 To: Sean Christopherson , Ashish Kalra References: From: Brijesh Singh Message-ID: Date: Fri, 4 Dec 2020 11:16:44 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [70.112.153.56] X-ClientProxiedBy: DM5PR07CA0072.namprd07.prod.outlook.com (2603:10b6:4:ad::37) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from Brijeshs-MacBook-Pro.local (70.112.153.56) by DM5PR07CA0072.namprd07.prod.outlook.com (2603:10b6:4:ad::37) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3632.17 via Frontend Transport; Fri, 4 Dec 2020 17:16:47 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-HT: Tenant X-MS-Office365-Filtering-Correlation-Id: 19ad94d8-4fff-44ac-0746-08d89878630d X-MS-TrafficTypeDiagnostic: SN1PR12MB2366: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:10000; X-MS-Exchange-SenderADCheck: 1 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: VNPgCkh3zkDwFWj/zji+dOiPX9hoNWnS0huT1SCAkfnx+kNIZyQ9mBbtOljkf4dNUzqLzt4KhTCYaZS3oVdrp3M/TvvofjoMlJv0IeFbFI20F5kaUd/mKlN1j4/hzF3FWNNmnA7rgtahlmSrI+7EF5RHHehDTAwJ4ljowiY+E6/EetJdVSFYtmemP6aGhQjIga1LS9MYfbR+WxuwB7kvvUIl4FNZiM6oBQgJAeS+6+r2iOaHO+/Ectc17c2BhQCo4M2EzjeI7GKMo6Ja5mI8ZYP1S9OaOIoYy/Pu3/hXBZPE9/WyF0dk511IJhGXEP+2ZjnNB8EvTo9uasDYPggUC4jUgNytih/Ov1u4+2Ltk1p4hfWabRlipMTCFBIcsrupGa2HiO79pULjEqEzZScMZSnNVX3uSCRU2IHOyjgdJt8= 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)(376002)(366004)(39860400002)(346002)(396003)(136003)(66556008)(6486002)(26005)(6666004)(186003)(16526019)(31696002)(6636002)(6512007)(4326008)(8676002)(8936002)(44832011)(2906002)(66476007)(66946007)(36756003)(2616005)(6506007)(956004)(52116002)(316002)(110136005)(7416002)(53546011)(478600001)(31686004)(86362001)(5660300002)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData: =?utf-8?B?d3EyOUFDbUM0cW12MStQYTQzRVJsZE1PaFR0NDBqWE5JdTc1TXk0WXZpaDBJ?= =?utf-8?B?MHNUNE1mM2hrTjRrenVDYWZ4Qm1yQXIxN2dZUVIxcXowK1ZEWVFrWGdQeHQ1?= =?utf-8?B?cG9PQ25manhFYWt6aStrUHE1THRJWXpwSTNJR2s0VGFpV2d2d2VMTWhzOWhp?= =?utf-8?B?Q3FvdzA1U3ZtTWIxckdxU1RWYkdBL3dTMmxWRTBJUnNwV0c3UC9acnYrTHov?= =?utf-8?B?TUlGdi90UitxdEVuTkx5bmhFWjJxN0pjQU9IK1BKd0xNUmV6a1pJeFpaclZn?= =?utf-8?B?NUc1TEV1MWRxQTJRbDZyR0I3eFBYZEh6SXl6OEQycFBuZTFEcjhTM2tuMDZI?= =?utf-8?B?WFVrMXhqbEQ1cjBPNEZCYkNHN3J4QzZPemFkQTJZSU1uYmlmc2dNWnVsYm1X?= =?utf-8?B?Z296M2lVbmdFQnlHcm1naWJZOTNib1d4RnVYcXpMc0RycGRDVWdsOGV0SCtJ?= =?utf-8?B?Z0paaEtXcFJxZmpoOXRiSjFWKytDdnNEQUxEdkpEUzRjOXBoYlVOdVpaOW1p?= =?utf-8?B?RHRnY244TGdIZkYxd1hWM3ZaSGsvOXV4eHBMclc0Z3RBU0lTeld2T3lZdWY3?= =?utf-8?B?OWxXVHM3cDViSW8wZHc2aUdLWTFVM3FERk80Uzc0SXFSanNmWmJwWFRpSFBB?= =?utf-8?B?OU1hcGRGYlpMc1Uwcm05V2dUb05jei80K1RaVzFhR2VSbTkwUFBzMzZjcC96?= =?utf-8?B?MmhPY2krQk9Mcnc1NVdRcHpzd1IrOHFFNk8wbHBMTU5vNGFPWFJYVlRiNjAw?= =?utf-8?B?b3JWSlN3YTFLdjc5bE81WnM0aVJja1BNYmx5VWtzaU1rblh6VXkrNlg5Wlh6?= =?utf-8?B?OHVGVkVmRDdHVE9LaWN5eDlmZGRZSW1VTVJpV3hqS0N6ditIdDY0QWI5K0VH?= =?utf-8?B?VWlDaWp1R3JWeEZxeDdRNmxLS05qM2p3Qis5K0U5Mk5FZEJoeU1ubzNGaVhD?= =?utf-8?B?VERpanRORnN5S0dzaTJ3QVQ2WC9QWGlVbjUrVGgxN250bHhTUlRoNVFBcXpm?= =?utf-8?B?eUdMYVBUc2JBbEduOTlHTzRoR0ZNRzJ6NUFPUENPVHdoMTZnaDgvdFVVdjFW?= =?utf-8?B?WWpuNmkyWnNWV2ZSaEF4YTEwSEZWVG05ZFlQZW5WbDFWSjNrcE5FSGFodDBG?= =?utf-8?B?T2EzNkpJZ09JYjZreTVPYyttU01ZQ1g5RGE2Mi9zZkk0djVIMEIzbmZJY0hR?= =?utf-8?B?SERkYytvNFdpYW5uYUV3ZVlnNDYyWGlmUXhXVWtnY0FiNmJXNVBDNTUwcjc2?= =?utf-8?B?eGg3WG1na3JyUE96dk9ZN0dNVVVZczZxL0tCaXZVcnc2NkZCUDYxQjlpcXVx?= =?utf-8?Q?7OQ8PxBxo7uc/Nl9WYMAHPNWyauxc/uBC1?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 19ad94d8-4fff-44ac-0746-08d89878630d X-MS-Exchange-CrossTenant-AuthSource: SN6PR12MB2718.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Dec 2020 17:16:50.0499 (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: HZ/5xfVRbzmuu4XiOCyJQMrWFt5n55wObQinGElilB8e8DD6Id5YFMWlJepakoZyatgj97Z1mnYWMbbYhoJZzQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN1PR12MB2366 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 12/2/20 6:34 PM, Sean Christopherson wrote: > On Tue, Dec 01, 2020, Ashish Kalra wrote: >> From: Brijesh Singh >> >> KVM hypercall framework relies on alternative framework to patch the >> VMCALL -> VMMCALL on AMD platform. If a hypercall is made before >> apply_alternative() is called then it defaults to VMCALL. The approach >> works fine on non SEV guest. A VMCALL would causes #UD, and hypervisor >> will be able to decode the instruction and do the right things. But >> when SEV is active, guest memory is encrypted with guest key and >> hypervisor will not be able to decode the instruction bytes. >> >> Add SEV specific hypercall3, it unconditionally uses VMMCALL. The hypercall >> will be used by the SEV guest to notify encrypted pages to the hypervisor. > What if we invert KVM_HYPERCALL and X86_FEATURE_VMMCALL to default to VMMCALL > and opt into VMCALL? It's a synthetic feature flag either way, and I don't > think there are any existing KVM hypercalls that happen before alternatives are > patched, i.e. it'll be a nop for sane kernel builds. If we invert the X86_FEATURE_VMMCALL to default to VMMCALL then it should work fine without this patch. So far there was no hypercall made before the alternative patching took place. Since the page state change can occur much before the alternative patching so we need to default to VMMCALL when SEV is active. > I'm also skeptical that a KVM specific hypercall is the right approach for the > encryption behavior, but I'll take that up in the patches later in the series. Great, I am open to explore other alternative approaches. > >> Cc: Thomas Gleixner >> Cc: Ingo Molnar >> Cc: "H. Peter Anvin" >> Cc: Paolo Bonzini >> Cc: "Radim Krčmář" >> Cc: Joerg Roedel >> Cc: Borislav Petkov >> Cc: Tom Lendacky >> Cc: x86@kernel.org >> Cc: kvm@vger.kernel.org >> Cc: linux-kernel@vger.kernel.org >> Reviewed-by: Steve Rutherford >> Reviewed-by: Venu Busireddy >> Signed-off-by: Brijesh Singh >> Signed-off-by: Ashish Kalra >> --- >> arch/x86/include/asm/kvm_para.h | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h >> index 338119852512..bc1b11d057fc 100644 >> --- a/arch/x86/include/asm/kvm_para.h >> +++ b/arch/x86/include/asm/kvm_para.h >> @@ -85,6 +85,18 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1, >> return ret; >> } >> >> +static inline long kvm_sev_hypercall3(unsigned int nr, unsigned long p1, >> + unsigned long p2, unsigned long p3) >> +{ >> + long ret; >> + >> + asm volatile("vmmcall" >> + : "=a"(ret) >> + : "a"(nr), "b"(p1), "c"(p2), "d"(p3) >> + : "memory"); >> + return ret; >> +} >> + >> #ifdef CONFIG_KVM_GUEST >> bool kvm_para_available(void); >> unsigned int kvm_arch_para_features(void); >> -- >> 2.17.1 >>