[PATCH v8 02/11] iommu: Add max_pasids field in struct dev_iommu

Lu Baolu
2022-06-07T01:53:53Z

Use this field to save the number of PASIDs that a device is able to
consume. It is a generic attribute of a device and lifting it into the
per-device dev_iommu struct could help to avoid the boilerplate code
in various IOMMU drivers.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
include/linux/iommu.h | 2 ++
drivers/iommu/iommu.c | 26 ++++++++++++++++++++++++++
2 files changed, 28 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 03fbb1b71536..d50afb2c9a09 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -364,6 +364,7 @@ struct iommu_fault_param {
* @fwspec: IOMMU fwspec data
* @iommu_dev: IOMMU device this device is linked to
* @priv: IOMMU Driver private data
+ * @max_pasids: number of PASIDs device can consume
*
* TODO: migrate other per device data pointers under iommu_dev_data, e.g.
* struct iommu_group *iommu_group;
@@ -375,6 +376,7 @@ struct dev_iommu {
struct iommu_fwspec *fwspec;
struct iommu_device *iommu_dev;
void *priv;
+ u32 max_pasids;
};

int iommu_device_register(struct iommu_device *iommu,
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 847ad47a2dfd..adac85ccde73 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -20,6 +20,7 @@
#include <linux/idr.h>
#include <linux/err.h>
#include <linux/pci.h>
+#include <linux/pci-ats.h>
#include <linux/bitops.h>
#include <linux/property.h>
#include <linux/fsl/mc.h>
@@ -218,6 +219,30 @@ static void dev_iommu_free(struct device *dev)
kfree(param);
}

+static u32 dev_iommu_get_max_pasids(struct device *dev)
+{
+ u32 max_pasids = dev->iommu->iommu_dev->max_pasids;
+ u32 num_bits;
+ int ret;
+
+ if (!max_pasids)
+ return 0;
+
+ if (dev_is_pci(dev)) {
+ ret = pci_max_pasids(to_pci_dev(dev));
+ if (ret < 0)
+ return 0;
+
+ return min_t(u32, max_pasids, ret);
+ }
+
+ ret = device_property_read_u32(dev, "pasid-num-bits", &num_bits);
+ if (ret)
+ return 0;
+
+ return min_t(u32, max_pasids, 1UL << num_bits);
+}
+
static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
{
const struct iommu_ops *ops = dev->bus->iommu_ops;
@@ -243,6 +268,7 @@ static int __iommu_probe_device(struct device *dev, struct list_head *group_list
}

dev->iommu->iommu_dev = iommu_dev;
+ dev->iommu->max_pasids = dev_iommu_get_max_pasids(dev);

group = iommu_group_get_for_dev(dev);
if (IS_ERR(group)) {
--
2.25.1