[PATCH v14 02/13] iommu: Add max_pasids field in struct dev_iommu

From: Lu Baolu
Date: Fri Sep 23 2022 - 20:18:52 EST


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@xxxxxxxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Yi Liu <yi.l.liu@xxxxxxxxx>
Tested-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
Tested-by: Tony Zhu <tony.zhu@xxxxxxxxx>
---
include/linux/iommu.h | 2 ++
drivers/iommu/iommu.c | 20 ++++++++++++++++++++
2 files changed, 22 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index e3af4f46e6e0..ac3f6c6dcc6d 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -368,6 +368,7 @@ 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 this device can consume
*
* TODO: migrate other per device data pointers under iommu_dev_data, e.g.
* struct iommu_group *iommu_group;
@@ -379,6 +380,7 @@ 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 65a3b3d886dc..297ac79bc21c 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -21,6 +21,7 @@
#include <linux/idr.h>
#include <linux/err.h>
#include <linux/pci.h>
+#include <linux/pci-ats.h>
#include <linux/bitops.h>
#include <linux/platform_device.h>
#include <linux/property.h>
@@ -278,6 +279,24 @@ static void dev_iommu_free(struct device *dev)
kfree(param);
}

+static u32 dev_iommu_get_max_pasids(struct device *dev)
+{
+ u32 max_pasids = 0, bits = 0;
+ int ret;
+
+ if (dev_is_pci(dev)) {
+ ret = pci_max_pasids(to_pci_dev(dev));
+ if (ret > 0)
+ max_pasids = ret;
+ } else {
+ ret = device_property_read_u32(dev, "pasid-num-bits", &bits);
+ if (!ret)
+ max_pasids = 1UL << bits;
+ }
+
+ return min_t(u32, max_pasids, dev->iommu->iommu_dev->max_pasids);
+}
+
static int __iommu_probe_device(struct device *dev, struct list_head *group_list)
{
const struct iommu_ops *ops = dev->bus->iommu_ops;
@@ -303,6 +322,7 @@ 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)) {
--
2.34.1