[PATCH v2 2/6] iommu: Configure default domain with def_domain_type

From: Lu Baolu
Date: Fri Mar 13 2020 - 21:09:54 EST


With the def_domain_type introduced, iommu default domain framework
is now able to determine a proper default domain for a group. Let's
use this to configure a group's default domain.

If unlikely a device requires a special default domain type other
than that in use, iommu probe procedure will either allocate a new
domain according to the specified domain type, or (if the group has
other devices sitting in it) change the default domain. The vendor
iommu driver which exposes the def_domain_type callback should
guarantee that there're no multiple devices in a same group requires
differnt types of default domain.

Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
drivers/iommu/iommu.c | 93 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 90 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 3e3528436e0b..b6a7429d0b45 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1361,6 +1361,79 @@ struct iommu_group *fsl_mc_device_group(struct device *dev)
}
EXPORT_SYMBOL_GPL(fsl_mc_device_group);

+/**
+ * Changes the default domain of a group
+ *
+ * @group: The group for which the default domain should be changed
+ * @type: The new default domain type
+ *
+ * The caller should hold the group->mutex before call into this function.
+ * Returns 0 on success and error code on failure.
+ */
+static int iommu_group_change_def_domain(struct iommu_group *group, int type)
+{
+ struct group_device *grp_dev, *temp;
+ struct iommu_domain *new, *old;
+ const struct iommu_ops *ops;
+ int ret = 0;
+
+ if ((type != IOMMU_DOMAIN_IDENTITY && type != IOMMU_DOMAIN_DMA) ||
+ !group->default_domain || type == group->default_domain->type ||
+ !group->default_domain->ops)
+ return -EINVAL;
+
+ if (group->domain != group->default_domain)
+ return -EBUSY;
+
+ iommu_group_ref_get(group);
+ old = group->default_domain;
+ ops = group->default_domain->ops;
+
+ /* Allocate a new domain of requested type. */
+ new = ops->domain_alloc(type);
+ if (!new) {
+ ret = -ENOMEM;
+ goto domain_out;
+ }
+ new->type = type;
+ new->ops = ops;
+ new->pgsize_bitmap = group->default_domain->pgsize_bitmap;
+
+ group->default_domain = new;
+ group->domain = new;
+ list_for_each_entry_safe(grp_dev, temp, &group->devices, list) {
+ struct device *dev;
+
+ dev = grp_dev->dev;
+ if (device_is_bound(dev)) {
+ ret = -EINVAL;
+ goto device_out;
+ }
+
+ iommu_group_create_direct_mappings(group, dev);
+ ret = __iommu_attach_device(group->domain, dev);
+ if (ret)
+ goto device_out;
+
+ ret = ops->add_device(dev);
+ if (ret)
+ goto device_out;
+ }
+
+ iommu_group_put(group);
+ iommu_domain_free(old);
+
+ return 0;
+
+device_out:
+ group->default_domain = old;
+ __iommu_attach_group(old, group);
+ iommu_domain_free(new);
+domain_out:
+ iommu_group_put(group);
+ return ret;
+}
+
/**
* iommu_group_get_for_dev - Find or create the IOMMU group for a device
* @dev: target device
@@ -1375,6 +1448,7 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
{
const struct iommu_ops *ops = dev->bus->iommu_ops;
struct iommu_group *group;
+ int dev_def_type = 0;
int ret;

group = iommu_group_get(dev);
@@ -1391,20 +1465,24 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
if (IS_ERR(group))
return group;

+ if (ops->def_domain_type)
+ dev_def_type = ops->def_domain_type(dev);
+
/*
* Try to allocate a default domain - needs support from the
* IOMMU driver.
*/
if (!group->default_domain) {
struct iommu_domain *dom;
+ int type = dev_def_type ? : iommu_def_domain_type;

- dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
- if (!dom && iommu_def_domain_type != IOMMU_DOMAIN_DMA) {
+ dom = __iommu_domain_alloc(dev->bus, type);
+ if (!dom && type != IOMMU_DOMAIN_DMA) {
dom = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_DMA);
if (dom) {
dev_warn(dev,
"failed to allocate default IOMMU domain of type %u; falling back to IOMMU_DOMAIN_DMA",
- iommu_def_domain_type);
+ type);
}
}

@@ -1418,6 +1496,15 @@ struct iommu_group *iommu_group_get_for_dev(struct device *dev)
DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
&attr);
}
+ } else if (dev_def_type &&
+ dev_def_type != group->default_domain->type) {
+ mutex_lock(&group->mutex);
+ ret = iommu_group_change_def_domain(group, dev_def_type);
+ mutex_unlock(&group->mutex);
+ if (ret) {
+ iommu_group_put(group);
+ return ERR_PTR(ret);
+ }
}

ret = iommu_group_add_device(group, dev);
--
2.17.1