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Wed, 26 Aug 2026 03:50:17 +0000 Message-ID: <5d04e5d6-6a8f-4bc1-afe9-195310bae909@intel.com> Date: Tue, 25 Aug 2026 20:50:14 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 0/7] KVM: x86: Add LASS virtualization support To: Sohil Mehta , , CC: Sean Christopherson , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Shuah Khan , Binbin Wu , Peter Zijlstra , "Chang S . Bae" , Kai Huang , Fuad Tabba , Chao Gao , Yosry Ahmed , Claudio Imbrenda , David Matlack , Bala-Vignesh-Reddy , Rick Edgecombe , , References: <20260806011536.4172258-1-sohil.mehta@intel.com> Content-Language: en-US From: Kishen Maloor In-Reply-To: <20260806011536.4172258-1-sohil.mehta@intel.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SJ0PR05CA0187.namprd05.prod.outlook.com (2603:10b6:a03:330::12) To DS0PR11MB8050.namprd11.prod.outlook.com (2603:10b6:8:117::5) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS0PR11MB8050:EE_|CH3PR11MB8660:EE_ X-MS-Office365-Filtering-Correlation-Id: 195cce53-33e6-4da7-3c12-08df032524d9 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|23010399003|366016|7416014|376014|6133799003|10067099003|56012099006|11063799006|22082099003|18002099003; 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Host support for LASS > has been merged [1][2]. This series adds the KVM virtualization support. > I tested this series on Sierra Forest, using the QEMU support linked below to expose LASS to the guest. Covered: - Guest enumeration of LASS and enabling of CR4.LASS. - User accesses to supervisor addresses on hardware and under the forced emulation prefix. - Supervisor accesses to user addresses from a guest kernel module under the forced emulation prefix: reads and writes, RFLAGS.AC suppression, SMAP=0 behavior, implicit descriptor-table accesses, and violations at a branch target. - Nested VMX: VMCLEAR with a low operand address, taking a #GP at RFLAGS.AC=0 and completing at AC=1, via get_vmx_mem_address() -> vmx_is_lass_violation(). Not covered: the TSS I/O bitmap paths in patch 2, and ENCLS. QEMU changes to expose LASS to guests: https://lore.kernel.org/all/20260826035734.114685-1-kishen.maloor@intel.com/ Tested-by: Kishen Maloor