Hi Robin,

-----Original Message-----
From: Robin Murphy [mailto:robin.murphy@arm.com]
Sent: 07 May 2021 11:02
To: Shameerali Kolothum Thodi <redacted>;
linux-arm-kernel@lists.infradead.org; linux-acpi@vger.kernel.org;
iommu@lists.linux-foundation.org
Cc: Linuxarm <redacted>; lorenzo.pieralisi@arm.com;
joro@8bytes.org; wanghuiqiang [off-list ref]; Guohanjun
(Hanjun Guo) [off-list ref]; steven.price@arm.com;
Sami.Mujawar@arm.com; jon@solid-run.com; eric.auger@redhat.com
Subject: Re: [PATCH v3 08/10] iommu/arm-smmu-v3: Reserve any RMR regions
associated with a dev

On 2021-04-20 09:27, Shameer Kolothum wrote:

quoted

Get RMR regions associated with a dev reserved so that there is
a unity mapping for them in SMMU.

Signed-off-by: Shameer Kolothum

[off-list ref]

quoted

---
  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 29

+++++++++++++++++++++

quoted

  1 file changed, 29 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

quoted

index 14e9c7034c04..8bacedf7bb34 100644

--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2531,6 +2531,34 @@ static int arm_smmu_of_xlate(struct device *dev,

struct of_phandle_args *args)

quoted

  	return iommu_fwspec_add_ids(dev, args->args, 1);
  }

+static bool arm_smmu_dev_has_rmr(struct arm_smmu_master *master,
+				 struct iommu_rmr *e)
+{
+	int i;
+
+	for (i = 0; i < master->num_sids; i++) {
+		if (e->sid == master->sids[i])
+			return true;
+	}
+
+	return false;
+}
+
+static void arm_smmu_rmr_get_resv_regions(struct device *dev,
+					  struct list_head *head)
+{
+	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	struct arm_smmu_device *smmu = master->smmu;
+	struct iommu_rmr *rmr;
+
+	list_for_each_entry(rmr, &smmu->rmr_list, list) {
+		if (!arm_smmu_dev_has_rmr(master, rmr))
+			continue;
+
+		iommu_dma_get_rmr_resv_regions(dev, rmr, head);
+	}
+}
+

TBH I wouldn't have thought we need a driver-specific hook for this, or
is it too painful to correlate fwspec->iommu_fwnode back to the relevant
IORT node generically?

From a quick look, I think I could get rid of the above with something like below,

------8<----
+static bool iommu_dma_dev_has_rmr(struct iommu_fwspec *fwspec,
+                                 struct iommu_rmr *e)
+{
+       int i;
+
+       for (i = 0; i < fwspec->num_ids; i++) {
+                if (e->sid == fwspec->ids[i])
+                        return true;
+        }
+
+        return false;
+}
+
+
+void iommu_dma_get_rmr_resv_regions(struct device *dev, struct list_head *list)
+{
+       struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+       struct list_head rmr_list;
+       struct iommu_rmr *rmr;
+
+       INIT_LIST_HEAD(&rmr_list);
+       if (iommu_dma_get_rmrs(fwspec->iommu_fwnode, &rmr_list))
+               return;
        ...
+       list_for_each_entry(rmr, &rmr_list, list) {
+     
+       if (!iommu_dma_dev_has_rmr(fwspec, rmr)
+           continue;
+          ... 
+               region = iommu_alloc_resv_region(rmr->base_address,
+                                                rmr->length, prot,
+                                                type);
         ...
+       }
+}
 /**
  * iommu_dma_get_resv_regions - Reserved region driver helper
  * @dev: Device from iommu_get_resv_regions()

@@ -188,10 +242,11 @@ void iommu_dma_get_resv_regions(struct device *dev, struct list_head *list)
        if (!is_of_node(dev_iommu_fwspec_get(dev)->iommu_fwnode))
                iort_iommu_msi_get_resv_regions(dev, list);
 
+       iommu_dma_get_rmr_resv_regions(dev, list);
 }

----8<----

But looking at the SMMUv2 code, the fwspec->ids is MASK:SID, so I am not
sure the RMR sid can be compared directly to fwspec->ids above. Right? Or
is there a better way here?

Thanks,
Shameer

quoted

  static void arm_smmu_get_resv_regions(struct device *dev,
  				      struct list_head *head)
  {

@@ -2545,6 +2573,7 @@ static void arm_smmu_get_resv_regions(struct

device *dev,

quoted

  	list_add_tail(&region->list, head);

  	iommu_dma_get_resv_regions(dev, head);
+	arm_smmu_rmr_get_resv_regions(dev, head);
  }

  static bool arm_smmu_dev_has_feature(struct device *dev,

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