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[35.198.224.169]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2fc7e9325fesm8522382a91.46.2025.02.20.08.15.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Feb 2025 08:15:50 -0800 (PST) Date: Thu, 20 Feb 2025 16:15:40 +0000 From: Pranjal Shrivastava To: Nicolin Chen Cc: "Tian, Kevin" , "jgg@nvidia.com" , "corbet@lwn.net" , "will@kernel.org" , "joro@8bytes.org" , "suravee.suthikulpanit@amd.com" , "robin.murphy@arm.com" , "dwmw2@infradead.org" , "baolu.lu@linux.intel.com" , "shuah@kernel.org" , "linux-kernel@vger.kernel.org" , "iommu@lists.linux.dev" , "linux-arm-kernel@lists.infradead.org" , "linux-kselftest@vger.kernel.org" , "linux-doc@vger.kernel.org" , "eric.auger@redhat.com" , "jean-philippe@linaro.org" , "mdf@kernel.org" , "mshavit@google.com" , "shameerali.kolothum.thodi@huawei.com" , "smostafa@google.com" , "ddutile@redhat.com" , "Liu, Yi L" , "patches@lists.linux.dev" Subject: Re: [PATCH v6 14/14] iommu/arm-smmu-v3: Set MEV bit in nested STE for DoS mitigations Message-ID: References: <436ac2021bb3d75114ca0e45f25a6a8257489d3b.1737754129.git.nicolinc@nvidia.com> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Feb 18, 2025 at 10:53:55AM -0800, Nicolin Chen wrote: > > > Is MEV available only in nested mode? Otherwise it perhaps makes > > > sense to turn it on in all configurations in IOMMUFD paths... > > > > I think the arm-smmu-v3's iommufd implementation only supports nested > > which could be the reason. > > I guess what Kevin says is that non-nested STE should set the MEV > as well, e.g. BYPASS and ABORT, and perhaps stage-1-only case too > where the attaching domain = UNMANAGED. > Ohh okay, got it. Thanks! Praan