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client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by CY4PEPF0000EE36.mail.protection.outlook.com (10.167.242.42) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9203.9 via Frontend Transport; Tue, 7 Oct 2025 07:59:27 +0000 Received: from BLR-L1-NDADHANI (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.17; Tue, 7 Oct 2025 00:59:21 -0700 From: Nikunj A Dadhania To: Jim Mattson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. Peter Anvin" , Sean Christopherson , Paolo Bonzini , Pawan Gupta , "Tom Lendacky" , Jim Mattson , "Perry Yuan" , Sohil Mehta , "Xin Li (Intel)" , Joerg Roedel , Avi Kivity , , , Yosry Ahmed Subject: Re: [PATCH v2 1/2] KVM: x86: Advertise EferLmsleUnsupported to userspace In-Reply-To: <20251001001529.1119031-2-jmattson@google.com> References: <20251001001529.1119031-1-jmattson@google.com> <20251001001529.1119031-2-jmattson@google.com> Date: Tue, 7 Oct 2025 07:59:14 +0000 Message-ID: <85qzvfqh0t.fsf@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000EE36:EE_|BL1PR12MB5705:EE_ X-MS-Office365-Filtering-Correlation-Id: eaeaa804-9327-4f3c-729b-08de0577703c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|376014|1800799024|7416014|82310400026|921020; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?eCoYH2LiSa4UldhvG2UGK9YkcqJBQoqYoAZomnzqYjPJvgXFn6B5XbNlFGP1?= =?us-ascii?Q?qaTt/Wzqfvx8PQ36p8GABb4Bzrrl+It8zlN5mf3BbEicRzGCPxSpI/sELtQf?= =?us-ascii?Q?OnF4f4KBIIG5CTksL5Ju/25O0Z8tqchCTkopugAgD0AaDRRsO0i4GCRqNh5M?= =?us-ascii?Q?+npUSv73Ye1rICMmf5QqOu1AMimQ6tpTJ+6hJHchp39KFR7EB9tveI4aR2OW?= =?us-ascii?Q?BcsOT/aElxT1Ny20iLLd+pywdvHCm+C2Kqti4widn/wegZlKB80pJsZHHUZ0?= =?us-ascii?Q?+pkuPV0synoFJ6GLfEoYjveKkBO6GQ0OjgrKoBfe6L4swvmoNya78uQFGsKz?= =?us-ascii?Q?Pd60mG+IF8M8AciMnRrcwhnfDunfZTrjImHfImDugPDBAb6l/9z5cbc1bM0h?= =?us-ascii?Q?Nksy4iFC3GzaE0mOne1TYmXTAEx1srurKU1GmudyALcZu34ss1vY/5AJgs9V?= =?us-ascii?Q?kVMzX/yZLeXw5XgFeMhcHcwSRa7e2O2YIpeXzVbrgemEprsdAP4uB9It4fin?= =?us-ascii?Q?aShVPOlT5A2XzoHgsy4XJG2Z69L1umtsf9YE+++6xHqaHESqe7J/imn/95WX?= =?us-ascii?Q?FuhmMo1h8JYWuDcnJ3ObtNxmYE2U11U+WQbp2tdSIy6na33vIZZ0ymVJWCmP?= =?us-ascii?Q?iuJCaAAOHZDXCPyRDS0Gt+L9j256Zxc4Eb2r1g1VodFPQ1QaFC0Li7bJsxag?= =?us-ascii?Q?aQuWH4dkypxhLQufUxvCKnK6kAyuZi6KGTVfdWzcgWvu21yJ74/5RoTKW4hM?= =?us-ascii?Q?+1LVWeiuT3lzilIOUmfZ4agRwDFpZxRgAol0mOtl1089ucGDUm+v0Xf9m1eU?= =?us-ascii?Q?Ybx61eEx6kqMql9YLfgP0JEjcOTsTtJf9RfCzVPOBEdYVAwPxFLlyzYSAL8m?= =?us-ascii?Q?dSEtt7tVsGNoJTKDlQC0XrlaIdkfkQrCN0Mu5NozxjFCHxOmTnPpDWMwhZqF?= =?us-ascii?Q?7EsJCNAH6kevhE2vr6qnnC7qixqXj4w6j6VAsWjnlO8oLSNa0QY57fN64W0z?= =?us-ascii?Q?uGMRkhfJSnSWeWPE33/e2Ewo5BYLVfKG6hFps69YV6jbRCNuLjNZtsdhVjaa?= =?us-ascii?Q?z+WNAtwF2UzLKPJtwo7/du7Lx4StoQz6B1jZhtiNSKqGaHG6ESC3uppYpSM6?= =?us-ascii?Q?diiPp3FGsPdR+dpNqYgxqrxIB6Z//kk/lvPCa0ox7IEIRZPxQfQq9q7BWegh?= =?us-ascii?Q?yY+kTmbP+R4d/tsd07JLOJ12d2N3OwnVWSy4AnKdsgKnTHeN0Sr4rzW0wAsJ?= =?us-ascii?Q?XGX/TZA4TETJWzNHxIYSyfGXV0by2X89pu/BGnoydLmqgLmWrXj2iyi+/Ait?= =?us-ascii?Q?cpsN+POZPcriyLjTuoyH9+7YFGkBN78H9eON2r4rYXejemQAsuO3Pwq6EfKI?= =?us-ascii?Q?mY1o1lv2dZCFkUZL+ZpkQne5obkfxz62NQ4eav6k/MALvDl9cXLaqKEB+KhB?= =?us-ascii?Q?53akN1aP+oVOU7JE+SGTyK1cH74eCjIWanO95Iejzz/4k0jHwpcJbtG3crfO?= =?us-ascii?Q?UuOeoWflCyscDXjbIFkPKHV17gr/7qn5bmoGtTl2KoqZOAUlxlYwUN+KOz2r?= =?us-ascii?Q?ynViaM4V3UKMspyx0+9ktT/Y0OSsuEE+QSf7s7pa?= X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(36860700013)(376014)(1800799024)(7416014)(82310400026)(921020);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Oct 2025 07:59:27.4574 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: eaeaa804-9327-4f3c-729b-08de0577703c X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000EE36.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL1PR12MB5705 Jim Mattson writes: > CPUID.80000008H:EBX.EferLmsleUnsupported[bit 20] is a defeature > bit. When this bit is clear, EFER.LMSLE is supported. When this bit is > set, EFER.LMLSE is unsupported. KVM has never supported EFER.LMSLE, so > it cannot support a 0-setting of this bit. > > Pass through the bit in KVM_GET_SUPPORTED_CPUID to advertise the > unavailability of EFER.LMSLE to userspace. > > Signed-off-by: Jim Mattson Reviewed-by: Nikunj A Dadhania > --- > v1 -> v2: > Pass through the bit from hardware, rather than forcing it to be set. > > arch/x86/include/asm/cpufeatures.h | 1 + > arch/x86/kvm/cpuid.c | 1 + > 2 files changed, 2 insertions(+) > > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h > index 751ca35386b0..f9b593721917 100644 > --- a/arch/x86/include/asm/cpufeatures.h > +++ b/arch/x86/include/asm/cpufeatures.h > @@ -338,6 +338,7 @@ > #define X86_FEATURE_AMD_STIBP (13*32+15) /* Single Thread Indirect Branch Predictors */ > #define X86_FEATURE_AMD_STIBP_ALWAYS_ON (13*32+17) /* Single Thread Indirect Branch Predictors always-on preferred */ > #define X86_FEATURE_AMD_IBRS_SAME_MODE (13*32+19) /* Indirect Branch Restricted Speculation same mode protection*/ > +#define X86_FEATURE_EFER_LMSLE_MBZ (13*32+20) /* EFER.LMSLE must be zero */ > #define X86_FEATURE_AMD_PPIN (13*32+23) /* "amd_ppin" Protected Processor Inventory Number */ > #define X86_FEATURE_AMD_SSBD (13*32+24) /* Speculative Store Bypass Disable */ > #define X86_FEATURE_VIRT_SSBD (13*32+25) /* "virt_ssbd" Virtualized Speculative Store Bypass Disable */ > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index e2836a255b16..4823970611fd 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -1096,6 +1096,7 @@ void kvm_set_cpu_caps(void) > F(AMD_STIBP), > F(AMD_STIBP_ALWAYS_ON), > F(AMD_IBRS_SAME_MODE), > + F(EFER_LMSLE_MBZ), > F(AMD_PSFD), > F(AMD_IBPB_RET), > ); > -- > 2.51.0.618.g983fd99d29-goog