Re: [RFC PATCH 17/34] iommu/arm-smmu: Store device instead of group in arm_smmu_s2cr

[Joerg Roedel <joro@8bytes.org>]

On Wed, Apr 08, 2020 at 04:07:33PM +0100, Robin Murphy wrote:
> On 2020-04-08 3:37 pm, Joerg Roedel wrote:
> Isn't that exactly what I suggested? :)

Okay, I dropped this patch and updated the next one.

> I don't recall for sure, but knowing me, that bit of group bookkeeping is
> only where it currently is because it cheekily saves iterating the IDs a
> second time. I don't think there's any technical reason.

I leave it up to you to make any changes on that :)

Updated patch below. I also noticed that I deleted too much from
arm-smmu-v3 in the previous version, fixed that too.

From a1d2821235a6c26b668b47ec0e84ad0316524406 Mon Sep 17 00:00:00 2001
From: Joerg Roedel <jroedel@suse.de>
Date: Mon, 30 Mar 2020 17:39:04 +0200
Subject: [PATCH] iommu/arm-smmu: Convert to probe/release_device() call-backs

Convert the arm-smmu and arm-smmu-v3 drivers to use the probe_device() and
release_device() call-backs of iommu_ops, so that the iommu core code does the
group and sysfs setup.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/arm-smmu-v3.c | 38 ++++++++++--------------------------
 drivers/iommu/arm-smmu.c    | 39 ++++++++++++++-----------------------
 2 files changed, 25 insertions(+), 52 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 82508730feb7..42e1ee7e5197 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2914,27 +2914,26 @@ static bool arm_smmu_sid_in_range(struct arm_smmu_device *smmu, u32 sid)
 
 static struct iommu_ops arm_smmu_ops;
 
-static int arm_smmu_add_device(struct device *dev)
+static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 {
 	int i, ret;
 	struct arm_smmu_device *smmu;
 	struct arm_smmu_master *master;
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
-	struct iommu_group *group;
 
 	if (!fwspec || fwspec->ops != &arm_smmu_ops)
-		return -ENODEV;
+		return ERR_PTR(-ENODEV);
 
 	if (WARN_ON_ONCE(dev_iommu_priv_get(dev)))
-		return -EBUSY;
+		return ERR_PTR(-EBUSY);
 
 	smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode);
 	if (!smmu)
-		return -ENODEV;
+		return ERR_PTR(-ENODEV);
 
 	master = kzalloc(sizeof(*master), GFP_KERNEL);
 	if (!master)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	master->dev = dev;
 	master->smmu = smmu;
@@ -2975,30 +2974,15 @@ static int arm_smmu_add_device(struct device *dev)
 		master->ssid_bits = min_t(u8, master->ssid_bits,
 					  CTXDESC_LINEAR_CDMAX);
 
-	ret = iommu_device_link(&smmu->iommu, dev);
-	if (ret)
-		goto err_disable_pasid;
+	return &smmu->iommu;
 
-	group = iommu_group_get_for_dev(dev);
-	if (IS_ERR(group)) {
-		ret = PTR_ERR(group);
-		goto err_unlink;
-	}
-
-	iommu_group_put(group);
-	return 0;
-
-err_unlink:
-	iommu_device_unlink(&smmu->iommu, dev);
-err_disable_pasid:
-	arm_smmu_disable_pasid(master);
 err_free_master:
 	kfree(master);
 	dev_iommu_priv_set(dev, NULL);
-	return ret;
+	return ERR_PTR(ret);
 }
 
-static void arm_smmu_remove_device(struct device *dev)
+static void arm_smmu_release_device(struct device *dev)
 {
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 	struct arm_smmu_master *master;
@@ -3010,8 +2994,6 @@ static void arm_smmu_remove_device(struct device *dev)
 	master = dev_iommu_priv_get(dev);
 	smmu = master->smmu;
 	arm_smmu_detach_dev(master);
-	iommu_group_remove_device(dev);
-	iommu_device_unlink(&smmu->iommu, dev);
 	arm_smmu_disable_pasid(master);
 	kfree(master);
 	iommu_fwspec_free(dev);
@@ -3138,8 +3120,8 @@ static struct iommu_ops arm_smmu_ops = {
 	.flush_iotlb_all	= arm_smmu_flush_iotlb_all,
 	.iotlb_sync		= arm_smmu_iotlb_sync,
 	.iova_to_phys		= arm_smmu_iova_to_phys,
-	.add_device		= arm_smmu_add_device,
-	.remove_device		= arm_smmu_remove_device,
+	.probe_device		= arm_smmu_probe_device,
+	.release_device		= arm_smmu_release_device,
 	.device_group		= arm_smmu_device_group,
 	.domain_get_attr	= arm_smmu_domain_get_attr,
 	.domain_set_attr	= arm_smmu_domain_set_attr,
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index a6a5796e9c41..e622f4e33379 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -220,7 +220,7 @@ static int arm_smmu_register_legacy_master(struct device *dev,
  * With the legacy DT binding in play, we have no guarantees about
  * probe order, but then we're also not doing default domains, so we can
  * delay setting bus ops until we're sure every possible SMMU is ready,
- * and that way ensure that no add_device() calls get missed.
+ * and that way ensure that no probe_device() calls get missed.
  */
 static int arm_smmu_legacy_bus_init(void)
 {
@@ -1062,7 +1062,6 @@ static int arm_smmu_master_alloc_smes(struct device *dev)
 	struct arm_smmu_master_cfg *cfg = dev_iommu_priv_get(dev);
 	struct arm_smmu_device *smmu = cfg->smmu;
 	struct arm_smmu_smr *smrs = smmu->smrs;
-	struct iommu_group *group;
 	int i, idx, ret;
 
 	mutex_lock(&smmu->stream_map_mutex);
@@ -1090,18 +1089,9 @@ static int arm_smmu_master_alloc_smes(struct device *dev)
 		cfg->smendx[i] = (s16)idx;
 	}
 
-	group = iommu_group_get_for_dev(dev);
-	if (IS_ERR(group)) {
-		ret = PTR_ERR(group);
-		goto out_err;
-	}
-	iommu_group_put(group);
-
 	/* It worked! Now, poke the actual hardware */
-	for_each_cfg_sme(cfg, fwspec, i, idx) {
+	for_each_cfg_sme(cfg, fwspec, i, idx)
 		arm_smmu_write_sme(smmu, idx);
-		smmu->s2crs[idx].group = group;
-	}
 
 	mutex_unlock(&smmu->stream_map_mutex);
 	return 0;
@@ -1172,7 +1162,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 
 	/*
 	 * FIXME: The arch/arm DMA API code tries to attach devices to its own
-	 * domains between of_xlate() and add_device() - we have no way to cope
+	 * domains between of_xlate() and probe_device() - we have no way to cope
 	 * with that, so until ARM gets converted to rely on groups and default
 	 * domains, just say no (but more politely than by dereferencing NULL).
 	 * This should be at least a WARN_ON once that's sorted.
@@ -1382,7 +1372,7 @@ struct arm_smmu_device *arm_smmu_get_by_fwnode(struct fwnode_handle *fwnode)
 	return dev ? dev_get_drvdata(dev) : NULL;
 }
 
-static int arm_smmu_add_device(struct device *dev)
+static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 {
 	struct arm_smmu_device *smmu = NULL;
 	struct arm_smmu_master_cfg *cfg;
@@ -1403,7 +1393,7 @@ static int arm_smmu_add_device(struct device *dev)
 	} else if (fwspec && fwspec->ops == &arm_smmu_ops) {
 		smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode);
 	} else {
-		return -ENODEV;
+		return ERR_PTR(-ENODEV);
 	}
 
 	ret = -EINVAL;
@@ -1444,21 +1434,19 @@ static int arm_smmu_add_device(struct device *dev)
 	if (ret)
 		goto out_cfg_free;
 
-	iommu_device_link(&smmu->iommu, dev);
-
 	device_link_add(dev, smmu->dev,
 			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
 
-	return 0;
+	return &smmu->iommu;
 
 out_cfg_free:
 	kfree(cfg);
 out_free:
 	iommu_fwspec_free(dev);
-	return ret;
+	return ERR_PTR(ret);
 }
 
-static void arm_smmu_remove_device(struct device *dev)
+static void arm_smmu_release_device(struct device *dev)
 {
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
 	struct arm_smmu_master_cfg *cfg;
@@ -1475,13 +1463,11 @@ static void arm_smmu_remove_device(struct device *dev)
 	if (ret < 0)
 		return;
 
-	iommu_device_unlink(&smmu->iommu, dev);
 	arm_smmu_master_free_smes(cfg, fwspec);
 
 	arm_smmu_rpm_put(smmu);
 
 	dev_iommu_priv_set(dev, NULL);
-	iommu_group_remove_device(dev);
 	kfree(cfg);
 	iommu_fwspec_free(dev);
 }
@@ -1512,6 +1498,11 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
 	else
 		group = generic_device_group(dev);
 
+	/* Remember group for faster lookups */
+	if (!IS_ERR(group))
+		for_each_cfg_sme(cfg, fwspec, i, idx)
+			smmu->s2crs[idx].group = group;
+
 	return group;
 }
 
@@ -1628,8 +1619,8 @@ static struct iommu_ops arm_smmu_ops = {
 	.flush_iotlb_all	= arm_smmu_flush_iotlb_all,
 	.iotlb_sync		= arm_smmu_iotlb_sync,
 	.iova_to_phys		= arm_smmu_iova_to_phys,
-	.add_device		= arm_smmu_add_device,
-	.remove_device		= arm_smmu_remove_device,
+	.probe_device		= arm_smmu_probe_device,
+	.release_device		= arm_smmu_release_device,
 	.device_group		= arm_smmu_device_group,
 	.domain_get_attr	= arm_smmu_domain_get_attr,
 	.domain_set_attr	= arm_smmu_domain_set_attr,
-- 
2.25.1