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Tue, 4 Aug 2020 15:16:21 +0000 Cc: brijesh.singh@amd.com, Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Lendacky Subject: Re: [RFC PATCH] KVM: SVM: Disallow SEV if NPT is disabled To: Sean Christopherson , Paolo Bonzini References: <20200731205116.14891-1-sean.j.christopherson@intel.com> From: Brijesh Singh Message-ID: Date: Tue, 4 Aug 2020 10:16:18 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 In-Reply-To: <20200731205116.14891-1-sean.j.christopherson@intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: DM5PR06CA0072.namprd06.prod.outlook.com (2603:10b6:3:37::34) 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 DM5PR06CA0072.namprd06.prod.outlook.com (2603:10b6:3:37::34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3239.17 via Frontend Transport; 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X-MS-Exchange-AntiSpam-MessageData: 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 X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: c07cdbff-f5d8-47e7-51ed-08d838895809 X-MS-Exchange-CrossTenant-AuthSource: SN6PR12MB2718.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Aug 2020 15:16:21.5123 (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: +G9Yp+TUC9ortzRykLMJ39hS+b8T10FBgOZJ17iixe+Ch2fggif0ixOWhT04ooy9tsmduWDtlxDJPUI2TnYJ0g== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR12MB4495 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 7/31/20 3:51 PM, Sean Christopherson wrote: > Forcefully turn off SEV if NPT is disabled, e.g. via module param. SEV > requires NPT as the C-bit only exists if NPT is active. > > Fixes: e9df09428996f ("KVM: SVM: Add sev module_param") > Cc: stable@vger.kernel.org > Cc: Tom Lendacky > Cc: Brijesh Singh > Signed-off-by: Sean Christopherson > --- > > RFC as it's entirely possible that I am completely misunderstanding how > SEV works. Compile tested only. Reviewed-By: Brijesh Singh > > arch/x86/kvm/svm/svm.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index 783330d0e7b88..e30629593458b 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -860,8 +860,14 @@ static __init int svm_hardware_setup(void) > kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE); > } > > + if (!boot_cpu_has(X86_FEATURE_NPT)) > + npt_enabled = false; > + > + if (npt_enabled && !npt) > + npt_enabled = false; > + > if (sev) { > - if (boot_cpu_has(X86_FEATURE_SEV) && > + if (boot_cpu_has(X86_FEATURE_SEV) && npt_enabled && > IS_ENABLED(CONFIG_KVM_AMD_SEV)) { > r = sev_hardware_setup(); > if (r) > @@ -879,12 +885,6 @@ static __init int svm_hardware_setup(void) > goto err; > } > > - if (!boot_cpu_has(X86_FEATURE_NPT)) > - npt_enabled = false; > - > - if (npt_enabled && !npt) > - npt_enabled = false; > - > kvm_configure_mmu(npt_enabled, PG_LEVEL_1G); > pr_info("kvm: Nested Paging %sabled\n", npt_enabled ? "en" : "dis"); >