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

[Lu Baolu]

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...@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

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