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[34.124.129.10]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-847a00029d3sm35570b3a.20.2026.06.29.09.40.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Jun 2026 09:40:26 -0700 (PDT) Date: Mon, 29 Jun 2026 16:40:21 +0000 From: Pranjal Shrivastava To: Nicolin Chen Cc: will@kernel.org, robin.murphy@arm.com, jgg@nvidia.com, joro@8bytes.org, kees@kernel.org, baolu.lu@linux.intel.com, kevin.tian@intel.com, miko.lenczewski@arm.com, smostafa@google.com, linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, stable@vger.kernel.org, jamien@nvidia.com Subject: Re: [PATCH rc v6 7/7] iommu/arm-smmu-v3: Detect ARM_SMMU_OPT_KDUMP_ADOPT in probe() Message-ID: References: <8f43bbe920466359465f2083cfd09a15ee8e5ff1.1779265413.git.nicolinc@nvidia.com> Precedence: bulk X-Mailing-List: stable@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: <8f43bbe920466359465f2083cfd09a15ee8e5ff1.1779265413.git.nicolinc@nvidia.com> On Wed, May 20, 2026 at 10:03:24AM -0700, Nicolin Chen wrote: > arm_smmu_device_hw_probe() runs before arm_smmu_init_structures(), so it's > natural to decide whether the kdump kernel must adopt the crashed kernel's > stream table. > > Given that memremap is used to adopt the old stream table, set this option > only on a coherent SMMU. > > And make sure SMMU isn't in Service Failure Mode. > > Fixes: b63b3439b856 ("iommu/arm-smmu-v3: Abort all transactions if SMMU is enabled in kdump kernel") > Cc: stable@vger.kernel.org # v6.12+ > Reviewed-by: Kevin Tian > Reviewed-by: Jason Gunthorpe > Signed-off-by: Nicolin Chen > --- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 31 +++++++++++++++++++++ > 1 file changed, 31 insertions(+) > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > index 851bcebfdb3d4..fb34c3ffee9fe 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -5353,6 +5353,33 @@ static void arm_smmu_get_httu(struct arm_smmu_device *smmu, u32 reg) > hw_features, fw_features); > } > > +static void arm_smmu_device_hw_probe_kdump(struct arm_smmu_device *smmu) > +{ > + u32 gerror, gerrorn, active; > + > + /* No adoption if SMMU is disabled (i.e., there is no in-flight DMA) */ > + if (!(readl_relaxed(smmu->base + ARM_SMMU_CR0) & CR0_SMMUEN)) > + return; > + > + /* For now, only support a coherent SMMU that works with MEMREMAP_WB */ > + if (!(smmu->features & ARM_SMMU_FEAT_COHERENCY)) { > + dev_warn(smmu->dev, > + "kdump: non-coherent SMMU unsupported; reset to block all DMAs\n"); > + return; > + } We seem to be checking it here right at the beginning, let's remove the redundant checks downstream? > + > + gerror = readl_relaxed(smmu->base + ARM_SMMU_GERROR); > + gerrorn = readl_relaxed(smmu->base + ARM_SMMU_GERRORN); > + active = gerror ^ gerrorn; > + if (active & GERROR_SFM_ERR) { > + dev_warn(smmu->dev, > + "kdump: SMMU in Service Failure Mode, must reset\n"); > + return; > + } > + > + smmu->options |= ARM_SMMU_OPT_KDUMP_ADOPT; > +} > + > static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu) > { > u32 reg; > @@ -5567,6 +5594,10 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu) > > dev_info(smmu->dev, "oas %lu-bit (features 0x%08x)\n", > smmu->oas, smmu->features); > + > + if (is_kdump_kernel()) > + arm_smmu_device_hw_probe_kdump(smmu); > + > return 0; > } Apart from that nit, Reviewed-by: Pranjal Shrivastava Thanks, Praan