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Subject[RFC PATCH 1/5] iommu: Add APIs for IOMMU PASID management
Date
This adds APIs for IOMMU drivers and device drivers to manage
the PASIDs used for DMA transfer and translation. It bases on
I/O ASID allocator for PASID namespace management and relies
on vendor specific IOMMU drivers for paravirtual PASIDs.

Below APIs are added:

* iommu_pasid_init(pasid)
- Initialize a PASID consumer. The vendor specific IOMMU
drivers are able to set the PASID range imposed by IOMMU
hardware through a callback in iommu_ops.

* iommu_pasid_exit(pasid)
- The PASID consumer stops consuming any PASID.

* iommu_pasid_alloc(pasid, min, max, private, *ioasid)
- Allocate a PASID and associate a @private data with this
PASID. The PASID value is stored in @ioaisd if returning
success.

* iommu_pasid_free(pasid, ioasid)
- Free a PASID to the pool so that it could be consumed by
others.

This also adds below helpers to lookup or iterate PASID items
associated with a consumer.

* iommu_pasid_for_each(pasid, func, data)
- Iterate PASID items of the consumer identified by @pasid,
and call @func() against each item. An error returned from
@func() will break the iteration.

* iommu_pasid_find(pasid, ioasid)
- Retrieve the private data associated with @ioasid.

Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/Kconfig | 1 +
drivers/iommu/iommu.c | 89 +++++++++++++++++++++++++++++++++++++++++++
include/linux/iommu.h | 73 +++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index d9a25715650e..39f2bb76c7b8 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -1,6 +1,7 @@
# IOMMU_API always gets selected by whoever wants it.
config IOMMU_API
bool
+ select IOASID

menuconfig IOMMU_SUPPORT
bool "IOMMU Hardware Support"
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 0b7c96d1425e..570b244897bb 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2082,3 +2082,92 @@ void iommu_detach_device_aux(struct iommu_domain *domain, struct device *dev)
}
}
EXPORT_SYMBOL_GPL(iommu_detach_device_aux);
+
+/*
+ * APIs for PASID used by IOMMU and the device drivers which depend
+ * on IOMMU.
+ */
+struct iommu_pasid *iommu_pasid_init(struct bus_type *bus)
+{
+ struct iommu_pasid *pasid;
+ int ret;
+
+ if (!bus || !bus->iommu_ops)
+ return NULL;
+
+ pasid = kzalloc(sizeof(*pasid), GFP_KERNEL);
+ if (!pasid)
+ return NULL;
+
+ pasid->ops = bus->iommu_ops;
+ /*
+ * The default range of an IOMMU PASID is from 0 to the full
+ * 20bit integer.
+ */
+ pasid->min = 0;
+ pasid->max = 0x100000;
+ /*
+ * Give vendor specific iommu drivers a chance to set the pasid
+ * limits imposed by the iommu hardware.
+ */
+ if (bus->iommu_ops->pasid_init) {
+ ret = bus->iommu_ops->pasid_init(pasid);
+ if (ret) {
+ kfree(pasid);
+ return NULL;
+ }
+ }
+
+ return pasid;
+}
+EXPORT_SYMBOL_GPL(iommu_pasid_init);
+
+void iommu_pasid_exit(struct iommu_pasid *pasid)
+{
+ kfree(pasid);
+}
+EXPORT_SYMBOL_GPL(iommu_pasid_exit);
+
+int iommu_pasid_alloc(struct iommu_pasid *pasid, ioasid_t min,
+ ioasid_t max, void *private, ioasid_t *ioasid)
+{
+ ioasid_t start, end, hw, val;
+ int ret = -EAGAIN;
+
+ start = max_t(int, min, pasid->min);
+ end = min_t(int, max, pasid->max);
+
+ if (pasid->ops->pasid_alloc)
+ ret = pasid->ops->pasid_alloc(pasid, start, end, &hw);
+
+ if (ret == -EAGAIN)
+ val = ioasid_alloc(&pasid->set, start, end, private);
+ else if (ret == 0)
+ val = ioasid_alloc(&pasid->set, hw, hw + 1, private);
+ else
+ goto hw_ret;
+
+ if (val == INVALID_IOASID)
+ goto ioasid_ret;
+
+ *ioasid = val;
+
+ return 0;
+
+ioasid_ret:
+ if (pasid->ops->pasid_free)
+ pasid->ops->pasid_free(pasid, hw);
+
+hw_ret:
+ return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(iommu_pasid_alloc);
+
+void iommu_pasid_free(struct iommu_pasid *pasid, ioasid_t ioasid)
+{
+ if (pasid->ops->pasid_free)
+ pasid->ops->pasid_free(pasid, ioasid);
+
+ ioasid_free(ioasid);
+}
+EXPORT_SYMBOL_GPL(iommu_pasid_free);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 9bf1b3f2457a..4f5202c8170b 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -20,6 +20,7 @@
#define __LINUX_IOMMU_H

#include <linux/scatterlist.h>
+#include <linux/ioasid.h>
#include <linux/device.h>
#include <linux/types.h>
#include <linux/errno.h>
@@ -48,6 +49,7 @@ struct bus_type;
struct device;
struct iommu_domain;
struct notifier_block;
+struct iommu_pasid;

/* iommu fault flags */
#define IOMMU_FAULT_READ 0x0
@@ -194,6 +196,9 @@ enum iommu_dev_attr {
* @of_xlate: add OF master IDs to iommu grouping
* @get_dev_attr: get per device IOMMU attributions
* @set_dev_attr: set per device IOMMU attributions
+ * @pasid_init: initialize a pasid consumer
+ * @pasid_alloc: allocate a pasid from low level driver
+ * @pasid_free: free a pasid to low level driver
* @pgsize_bitmap: bitmap of all possible supported page sizes
*/
struct iommu_ops {
@@ -246,6 +251,12 @@ struct iommu_ops {
int (*attach_dev_aux)(struct iommu_domain *domain, struct device *dev);
void (*detach_dev_aux)(struct iommu_domain *domain, struct device *dev);

+ /* IOMMU pasid callbacks */
+ int (*pasid_init)(struct iommu_pasid *pasid);
+ int (*pasid_alloc)(struct iommu_pasid *pasid, ioasid_t start,
+ ioasid_t end, ioasid_t *ioasid);
+ void (*pasid_free)(struct iommu_pasid *pasid, ioasid_t ioasid);
+
unsigned long pgsize_bitmap;
};

@@ -428,12 +439,41 @@ extern int iommu_attach_device_aux(struct iommu_domain *domain,
extern void iommu_detach_device_aux(struct iommu_domain *domain,
struct device *dev);

+/*
+ * Per IOMMU PASID consumer data.
+ */
+struct iommu_pasid {
+ ioasid_t max;
+ ioasid_t min;
+ struct ioasid_set set;
+ const struct iommu_ops *ops;
+
+ /* vendor specific iommu private data */
+ void *priv;
+};
+
+struct iommu_pasid *iommu_pasid_init(struct bus_type *bus);
+void iommu_pasid_exit(struct iommu_pasid *pasid);
+int iommu_pasid_alloc(struct iommu_pasid *pasid, ioasid_t min,
+ ioasid_t max, void *private, ioasid_t *ioasid);
+void iommu_pasid_free(struct iommu_pasid *pasid, ioasid_t iosid);
+static inline int
+iommu_pasid_for_each(struct iommu_pasid *pasid, ioasid_iter_t func, void *data)
+{
+ return ioasid_for_each(&pasid->set, func, data);
+}
+static inline void*
+iommu_pasid_find(struct iommu_pasid *pasid, ioasid_t ioasid)
+{
+ return ioasid_find(&pasid->set, ioasid);
+}
#else /* CONFIG_IOMMU_API */

struct iommu_ops {};
struct iommu_group {};
struct iommu_fwspec {};
struct iommu_device {};
+struct iommu_pasid {};

static inline bool iommu_present(struct bus_type *bus)
{
@@ -734,6 +774,39 @@ static inline void
iommu_detach_device_aux(struct iommu_domain *domain, struct device *dev)
{
}
+
+static inline struct iommu_pasid *
+iommu_pasid_init(struct bus_type *bus)
+{
+ return NULL;
+}
+
+static inline void iommu_pasid_exit(struct iommu_pasid *pasid)
+{
+}
+
+static inline int
+iommu_pasid_alloc(struct iommu_pasid *pasid, ioasid_t min,
+ ioasid_t max, void *private, ioasid_t *ioasid)
+{
+ return -ENODEV;
+}
+
+static inline void iommu_pasid_free(struct iommu_pasid *pasid, ioasid_t iosid)
+{
+}
+
+static inline int
+iommu_pasid_for_each(struct iommu_pasid *pasid, ioasid_iter_t func, void *data)
+{
+ return -ENODEV;
+}
+
+static inline void*
+iommu_pasid_find(struct iommu_pasid *pasid, ioasid_t ioasid)
+{
+ return NULL;
+}
#endif /* CONFIG_IOMMU_API */

#ifdef CONFIG_IOMMU_DEBUGFS
--
2.17.1
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