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[47.55.120.4]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8b5299a5f1dsm338261485a.13.2025.11.28.09.07.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Nov 2025 09:07:49 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vP1wi-00000003Q7z-2Cdq; Fri, 28 Nov 2025 13:07:48 -0400 Date: Fri, 28 Nov 2025 13:07:48 -0400 From: Jason Gunthorpe To: Mostafa Saleh Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, iommu@lists.linux.dev, catalin.marinas@arm.com, will@kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, joro@8bytes.org, jean-philippe@linaro.org, praan@google.com, danielmentz@google.com, mark.rutland@arm.com, qperret@google.com, tabba@google.com Subject: Re: [PATCH v5 17/27] iommu/arm-smmu-v3-kvm: Probe SMMU HW Message-ID: <20251128170748.GE812105@ziepe.ca> References: <20251117184815.1027271-1-smostafa@google.com> <20251117184815.1027271-18-smostafa@google.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; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251117184815.1027271-18-smostafa@google.com> On Mon, Nov 17, 2025 at 06:48:04PM +0000, Mostafa Saleh wrote: > +/* > + * Mini-probe and validation for the hypervisor. > + */ > +static int smmu_probe(struct hyp_arm_smmu_v3_device *smmu) > +{ > + u32 reg; > + > + /* IDR0 */ > + reg = readl_relaxed(smmu->base + ARM_SMMU_IDR0); > + smmu->features = smmu_idr0_features(reg); > + > + /* > + * Some MMU600 and MMU700 have errata that prevent them from using nesting, > + * not sure how can we identify those, so it's recommended not to enable this > + * drivers on such systems. > + * And preventing any of those will be too restrictive > + */ This driver is doing nesting though ?? Shouldn't you detect those IPs and not support a S1 at all so there is no nesting? Identity only? Jason