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Re: [PATCH v4 11/11] xen/arm: smmuv3: Add support for SMMUv3 driver

On 12.01.21 11:41, Rahul Singh wrote:

Hi Rahul

  -static int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args 
+static int arm_smmu_dt_xlate(struct device *dev,
+                               const struct dt_phandle_args *args)
-       return iommu_fwspec_add_ids(dev, args->args, 1);
+       int ret;
+       struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
Please bear in mind I am not familiar with the SMMU, but don't we need to 
perform a some kind
of sanity check of passed DT IOMMU specifier here?
I checked the code follow we will never hit the dt_xlate without IOMMU 
specifier but anyway I will add the sanity check.
By sanity check I meant to make sure that device ID (stream ID) is in allowed range (of course, if this is relevant for SMMU). For example, for IPMMU-VMSA we have a check that device ID (uTLB) is less than max uTLB number.

+static int arm_smmu_iommu_xen_domain_init(struct domain *d)
+       struct arm_smmu_xen_domain *xen_domain;
+       xen_domain = xzalloc(struct arm_smmu_xen_domain);
+       if (!xen_domain)
+               return -ENOMEM;
+       spin_lock_init(&xen_domain->lock);
+       INIT_LIST_HEAD(&xen_domain->contexts);
+       dom_iommu(d)->arch.priv = xen_domain;
+       return 0;
+static void __hwdom_init arm_smmu_iommu_hwdom_init(struct domain *d)
Both SMMUv2 and IPMMU perform some actions here. Any reason we don't need to do 
the same here?

     /* Set to false options not supported on ARM. */
     if ( iommu_hwdom_inclusive )
         "map-inclusive dom0-iommu option is not supported on ARM\n");
     iommu_hwdom_inclusive = false;
     if ( iommu_hwdom_reserved == 1 )
         "map-reserved dom0-iommu option is not supported on ARM\n");
     iommu_hwdom_reserved = 0;

I will add the above code for SMMUv3 also.


I was thinking about it, this is the third IOMMU driver on Arm which has to disable the _same_ unsupported options, probably this code wants to be folded in arch_iommu_hwdom_init() to avoid duplication?


Oleksandr Tyshchenko



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