-----Original Message-----
From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi at arm.com]
Sent: Monday, December 11, 2017 2:45 PM
To: Shameerali Kolothum Thodi <redacted>
Cc: will.deacon at arm.com; robin.murphy at arm.com; marc.zyngier at arm.com;
joro at 8bytes.org; John Garry [off-list ref]; xuwei (O)
[off-list ref]; Guohanjun (Hanjun Guo) [off-list ref];
iommu at lists.linux-foundation.org; linux-arm-kernel at lists.infradead.org; linux-
acpi at vger.kernel.org; devicetree at vger.kernel.org; Linuxarm
[off-list ref]
Subject: Re: [PATCH v10 1/3] ACPI/IORT: Add msi address regions reservation
helper

On Wed, Nov 29, 2017 at 02:14:47PM +0000, Shameer Kolothum wrote:

quoted

On some platforms msi parent address regions have to be excluded from
normal IOVA allocation in that they are detected and decoded in a HW
specific way by system components and so they cannot be considered normal
IOVA address space.

Add a helper function that retrieves ITS address regions - the msi
parent - 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. The function checks for the smmu model number and
only applies the msi reservation if the platform requires it.

Signed-off-by: Shameer Kolothum <redacted>
---
 drivers/acpi/arm64/iort.c        | 133

++++++++++++++++++++++++++++++++++++++-

quoted

 drivers/irqchip/irq-gic-v3-its.c |   3 +-
 include/linux/acpi_iort.h        |   7 ++-
 3 files changed, 138 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 95255ec..1c5fc36 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;
 };

@@ -161,14 +162,16 @@ 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

quoted

  */
-int iort_register_domain_token(int trans_id, struct fwnode_handle

*fw_node)

quoted

+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;

@@ -178,6 +181,7 @@ int iort_register_domain_token(int trans_id, struct

fwnode_handle *fw_node)

quoted

 	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);

@@ -581,6 +585,24 @@ int iort_pmsi_get_dev_id(struct device *dev, u32

*dev_id)

quoted

 	return -ENODEV;
 }

+static int __maybe_unused iort_find_its_base(u32 its_id, phys_addr_t *base)
+{
+	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;

Nit: if you need to return an int, use it as the "match" variable,
there is no point in using a bool.

int ret = -ENODEV;

if (its_msi_chip->translation_id == its_id) {
	...
	ret = 0;
	break;
}

return ret;

quoted

+}
+
 /**
  * iort_dev_find_its_id() - Find the ITS identifier for a device
  * @dev: The device.

@@ -740,6 +762,38 @@ static int __maybe_unused __get_pci_rid(struct

pci_dev *pdev, u16 alias,

quoted

 	return 0;
 }

+static bool __maybe_unused iort_hw_msi_resv_enable(struct device *dev,
+					struct acpi_iort_node *node)
+{
+	struct iort_fwnode *curr;
+	struct acpi_iort_node *iommu = NULL;
+	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+
+	if (WARN_ON(!fwspec || !fwspec->iommu_fwnode))

Remove WARN_ON() here, it seems excessive.

quoted

+		return false;
+
+	spin_lock(&iort_fwnode_lock);
+	list_for_each_entry(curr, &iort_fwnode_list, list) {
+		if (curr->fwnode == fwspec->iommu_fwnode) {
+			iommu = curr->iort_node;
+			break;
+		}
+	}
+	spin_unlock(&iort_fwnode_lock);

iort_get_iort_node() ?

quoted

+	if (iommu && (iommu->type == ACPI_IORT_NODE_SMMU_V3)) {
+		struct acpi_iort_smmu_v3 *smmu;
+
+		smmu = (struct acpi_iort_smmu_v3 *)iommu->node_data;
+		if (smmu->model ==

ACPI_IORT_SMMU_V3_HISILICON_HI161X) {

quoted

+			dev_notice(dev, "Enabling HiSilicon erratum

161010801\n");

quoted

+			return true;
+		}
+	}
+
+	return false;
+}
+
 static int arm_smmu_iort_xlate(struct device *dev, u32 streamid,
 			       struct fwnode_handle *fwnode,
 			       const struct iommu_ops *ops)

@@ -782,6 +836,77 @@ static inline int iort_add_device_replay(const struct

iommu_ops *ops,

quoted

 	return err;
 }
+
+/**
+ * iort_iommu_msi_get_resv_regions - Reserved region driver helper
+ * @dev: Device from iommu_get_resv_regions()
+ * @head: Reserved region list from iommu_get_resv_regions()
+ *
+ * Returns: Number of msi reserved regions on success (0 if platform
+ *          doesn't require the reservation or no associated msi regions),
+ *          appropriate error value otherwise. The ITS interrupt translation
+ *          space (ITS_base + 0x010000) associated with the device are the
+ *          msi reserved regions.
+ */
+int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head

*head)

quoted

+{
+	struct acpi_iort_its_group *its;
+	struct acpi_iort_node *node, *its_node = NULL;
+	int i, resv = 0;
+
+	node = iort_find_dev_node(dev);
+	if (!node)
+		return -ENODEV;

You may not need node, see below.

quoted

+	if (!iort_hw_msi_resv_enable(dev, node))

node is passed but effectively not used by the function.

quoted

+		return 0;
+
+	/*
+	 * Current logic to reserve ITS regions relies on HW topologies
+	 * where a given PCI or named component maps its IDs to only one
+	 * ITS group; if a PCI or named component can map its IDs to
+	 * different ITS groups through IORT mappings this function has
+	 * to be reworked to ensure we reserve regions for all ITS groups
+	 * a given PCI or named component may map IDs to.
+	 */
+	if (dev_is_pci(dev)) {
+		u32 rid;
+
+		pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid, &rid);
+		its_node = iort_node_map_id(node, rid, NULL,

IORT_MSI_TYPE);

quoted

+	} else {
+		for (i = 0; i < node->mapping_count; i++) {
+			its_node = iort_node_map_platform_id(node, NULL,
+							 IORT_MSI_TYPE, i);
+			if (its_node)
+				break;
+		}
+	}

Ok. So, how about doing:

for (i = 0; i < dev->iommu_fwspec->num_ids; i++) {
	its_node = iort_node_map_id(iommu_iort_node, dev->iommu_fwspec-

quoted

ids[i],

				    NULL, IORT_MSI_TYPE);
	if (its_node)
		break;
}

which removes the need for dev_is_pci() check and simplifies a bit, is
there any issue with that ?

iommu_iort_node can be returned by iort_hw_msi_resv_enable(), that
you can rename accordingly.

Thanks Lorenzo. I will address the comments and send the revised patch
after testing.

Much appreciated,
Shameer