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Wed, 16 Sep 2026 00:12:48 +0000 Message-ID: Date: Tue, 15 Sep 2026 17:12:46 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 4/7] KVM: VMX: Implement LASS violation check Content-Language: en-US To: Sean Christopherson CC: "Chang S. Bae" , , , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H . Peter Anvin" , Shuah Khan , Binbin Wu , Peter Zijlstra , Kai Huang , Fuad Tabba , Chao Gao , Yosry Ahmed , Claudio Imbrenda , David Matlack , Bala-Vignesh-Reddy , Kishen Maloor , Rick Edgecombe , , References: <20260806011536.4172258-1-sohil.mehta@intel.com> <20260806011536.4172258-5-sohil.mehta@intel.com> From: Sohil Mehta In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: BY1P220CA0004.NAMP220.PROD.OUTLOOK.COM (2603:10b6:a03:59d::15) To PH7PR11MB6932.namprd11.prod.outlook.com (2603:10b6:510:207::5) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH7PR11MB6932:EE_|DS4PPF900531A26:EE_ X-MS-Office365-Filtering-Correlation-Id: 62bfda2c-07c1-4a34-ae31-08df13873d66 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|366016|1800799024|7416014|23010399003|376014|4143699003|3023799007|10067099003|56012099006|11063799006|22082099003|18002099003; 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Someting along the > lines of "The basic flow is this: , but the actual behavior is far more > subtle due to many exceptions and edge cases". Great, how about this? > /* > * Check if an access violates LASS purely based on bit 63 of the linear address > * and whether the access targets the "wrong" half of the address space. The > * basic flow is straightforward: > * > * if (exempt from LASS) > * no violation; > * else if (user access) > * violation when address is in the supervisor half; > * else > * violation when address is in the user half; > * > * but the actual behavior is far more subtle due to the many exceptions and > * edge cases. For example, the implementation depends on which accesses are > * exempt, what constitutes a user access, and how supervisor data accesses > * differ from instruction fetches. > */ > bool vmx_is_lass_violation(struct kvm_vcpu *vcpu, gva_t gva, > unsigned int size, unsigned int flags) Sean, other than this, do you want to see any big change in the series? The sashiko complains are false-positives. There are a couple of nits to be addressed, and I need to change Binbin's SoBs into Reviewed-bys. Otherwise, I think the series (1-5) is getting ready to be picked up.