On Tue, Jul 25, 2017 at 06:32:40PM +0100, Robin Murphy wrote:

On 25/07/17 18:11, Lorenzo Pieralisi wrote:

quoted

On Tue, Jul 25, 2017 at 12:17:31PM +0100, Shameer Kolothum wrote:

quoted

The helper function retrieves ITS address regions through IORT
device <-> ITS mappings and reserves it so that these regions
will not be translated by IOMMU and will be excluded from IOVA
allocations. IOMMU drivers can use this to implement their
.get_resv_regions callback.

Signed-off-by: Shameer Kolothum <redacted>
---
 drivers/acpi/arm64/iort.c        | 91 ++++++++++++++++++++++++++++++++++++++--
 drivers/irqchip/irq-gic-v3-its.c |  3 +-
 include/linux/acpi_iort.h        |  8 +++-
 3 files changed, 97 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index a3215ee..e28f30c 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c

@@ -39,6 +39,7 @@
 struct iort_its_msi_chip {
 	struct list_head	list;
 	struct fwnode_handle	*fw_node;
+	phys_addr_t		base_addr;
 	u32			translation_id;
 };
 

@@ -136,14 +137,16 @@ typedef acpi_status (*iort_find_node_callback)
 static DEFINE_SPINLOCK(iort_msi_chip_lock);
 
 /**
- * iort_register_domain_token() - register domain token and related ITS ID
- * to the list from where we can get it back later on.
+ * iort_register_domain_token() - register domain token along with related
+ * ITS ID and base address to the list from where we can get it back later on.
  * @trans_id: ITS ID.
+ * @base: ITS base address.
  * @fw_node: Domain token.
  *
  * Returns: 0 on success, -ENOMEM if no memory when allocating list element
  */
-int iort_register_domain_token(int trans_id, struct fwnode_handle *fw_node)
+int iort_register_domain_token(int trans_id, phys_addr_t base,
+			       struct fwnode_handle *fw_node)
 {
 	struct iort_its_msi_chip *its_msi_chip;
 

@@ -153,6 +156,7 @@ int iort_register_domain_token(int trans_id, struct fwnode_handle *fw_node)
 
 	its_msi_chip->fw_node = fw_node;
 	its_msi_chip->translation_id = trans_id;
+	its_msi_chip->base_addr = base;
 
 	spin_lock(&iort_msi_chip_lock);
 	list_add(&its_msi_chip->list, &iort_msi_chip_list);

@@ -481,6 +485,24 @@ int iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
 	return -ENODEV;
 }
 
+static int iort_find_its_base(u32 its_id, phys_addr_t *base)

You have to tag it as __maybe_unused for the !IOMMU_API case.

quoted

+{
+	struct iort_its_msi_chip *its_msi_chip;
+	bool match = false;
+
+	spin_lock(&iort_msi_chip_lock);
+	list_for_each_entry(its_msi_chip, &iort_msi_chip_list, list) {
+		if (its_msi_chip->translation_id == its_id) {
+			*base = its_msi_chip->base_addr;
+			match = true;
+			break;
+		}
+	}
+	spin_unlock(&iort_msi_chip_lock);
+
+	return match ? 0 : -ENODEV;
+}
+
 /**
  * iort_dev_find_its_id() - Find the ITS identifier for a device
  * @dev: The device.

@@ -639,6 +661,67 @@ int iort_add_device_replay(const struct iommu_ops *ops, struct device *dev)
 
 	return err;
 }
+
+/**
+ * iort_iommu_its_get_resv_regions - Reserved region driver helper
+ * @dev: Device from iommu_get_resv_regions()
+ * @list: Reserved region list from iommu_get_resv_regions()
+ *
+ * Returns: Number of reserved regions on success(0 if no associated ITS),
+ *          appropriate error value otherwise.
+ *
+ * IOMMU drivers can use this to implement their .get_resv_regions callback
+ * for reserving the HW ITS address regions.

Stale comment.

quoted

+ */
+int iort_iommu_its_get_resv_regions(struct device *dev, struct list_head *head)
+{
+	int i;
+	struct acpi_iort_its_group *its;
+	struct acpi_iort_node *node, *its_node = NULL;
+	int resv = 0;

Nit: int i, resv = 0;

I can make these changes but I suspect this series will go via IOMMU
tree, let me know how you want to handle it.

Lorenzo

quoted

+	node = iort_find_dev_node(dev);
+	if (!node)
+		return -ENODEV;
+

I'd suggest we also want a comment here to clarify that we're currently
assuming straightforward topologies where all mappings for a given root
complex/named component target the same ITS group. Otherwise we're going
to need somewhat more logic to iterate the its_node processing over
every mapping (or every alias in the PCI case), but avoid creating
duplicate entries.

You have a point and we have time to update the code. Short of reserving
all ITS regions for every device that maps to one at least, we could (even
pre-compute instead of looking it up on the fly) create a list of ITS
identifiers a given IORT node may map to and use that to reserve the
regions.

Thoughts ?

Lorenzo