[PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support

[Lu Baolu <baolu.lu@linux.intel.com>]

The iommu_sva_domain represents a hardware pagetable that the IOMMU
hardware could use for SVA translation. This adds some infrastructure
to support SVA domain in the iommu common layer. It includes:

- Add a new struct iommu_sva_domain and new IOMMU_DOMAIN_SVA domain
  type.
- Add a new domain ops pointer in iommu_ops. The IOMMU drivers that
  support SVA should provide the callbacks.
- Add helpers to allocate and free an SVA domain.
- Add helpers to set an SVA domain to a device and the reverse
  operation.

Some buses, like PCI, route packets without considering the PASID value.
Thus a DMA target address with PASID might be treated as P2P if the
address falls into the MMIO BAR of other devices in the group. To make
things simple, the attach/detach interfaces only apply to devices
belonging to the singleton groups, and the singleton is immutable in
fabric i.e. not affected by hotplug.

The iommu_set/block_device_pasid() can be used for other purposes,
such as kernel DMA with pasid, mediation device, etc. Hence, it is put
in the iommu.c.

Suggested-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 include/linux/iommu.h         | 51 +++++++++++++++++++++++++
 drivers/iommu/iommu-sva-lib.h | 15 ++++++++
 drivers/iommu/iommu-sva-lib.c | 48 +++++++++++++++++++++++
 drivers/iommu/iommu.c         | 71 +++++++++++++++++++++++++++++++++++
 4 files changed, 185 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 0c358b7c583b..e8cf82d46ce1 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -64,6 +64,9 @@ struct iommu_domain_geometry {
 #define __IOMMU_DOMAIN_PT	(1U << 2)  /* Domain is identity mapped   */
 #define __IOMMU_DOMAIN_DMA_FQ	(1U << 3)  /* DMA-API uses flush queue    */
 
+#define __IOMMU_DOMAIN_SHARED	(1U << 4)  /* Page table shared from CPU  */
+#define __IOMMU_DOMAIN_HOST_VA	(1U << 5)  /* Host CPU virtual address */
+
 /*
  * This are the possible domain-types
  *
@@ -86,6 +89,8 @@ struct iommu_domain_geometry {
 #define IOMMU_DOMAIN_DMA_FQ	(__IOMMU_DOMAIN_PAGING |	\
 				 __IOMMU_DOMAIN_DMA_API |	\
 				 __IOMMU_DOMAIN_DMA_FQ)
+#define IOMMU_DOMAIN_SVA	(__IOMMU_DOMAIN_SHARED |	\
+				 __IOMMU_DOMAIN_HOST_VA)
 
 struct iommu_domain {
 	unsigned type;
@@ -254,6 +259,7 @@ struct iommu_ops {
 	int (*def_domain_type)(struct device *dev);
 
 	const struct iommu_domain_ops *default_domain_ops;
+	const struct iommu_domain_ops *sva_domain_ops;
 	unsigned long pgsize_bitmap;
 	struct module *owner;
 };
@@ -262,6 +268,8 @@ struct iommu_ops {
  * struct iommu_domain_ops - domain specific operations
  * @attach_dev: attach an iommu domain to a device
  * @detach_dev: detach an iommu domain from a device
+ * @set_dev_pasid: set an iommu domain to a pasid of device
+ * @block_dev_pasid: block pasid of device from using iommu domain
  * @map: map a physically contiguous memory region to an iommu domain
  * @map_pages: map a physically contiguous set of pages of the same size to
  *             an iommu domain.
@@ -282,6 +290,10 @@ struct iommu_ops {
 struct iommu_domain_ops {
 	int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
 	void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
+	int (*set_dev_pasid)(struct iommu_domain *domain, struct device *dev,
+			     ioasid_t pasid);
+	void (*block_dev_pasid)(struct iommu_domain *domain, struct device *dev,
+				ioasid_t pasid);
 
 	int (*map)(struct iommu_domain *domain, unsigned long iova,
 		   phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
@@ -677,6 +689,10 @@ int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner);
 void iommu_group_release_dma_owner(struct iommu_group *group);
 bool iommu_group_dma_owner_claimed(struct iommu_group *group);
 
+int iommu_set_device_pasid(struct iommu_domain *domain, struct device *dev,
+			   ioasid_t pasid);
+void iommu_block_device_pasid(struct iommu_domain *domain, struct device *dev,
+			      ioasid_t pasid);
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -1050,6 +1066,17 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 {
 	return false;
 }
+
+static inline int iommu_set_device_pasid(struct iommu_domain *domain,
+					 struct device *dev, ioasid_t pasid)
+{
+	return -ENODEV;
+}
+
+static inline void iommu_block_device_pasid(struct iommu_domain *domain,
+					    struct device *dev, ioasid_t pasid)
+{
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**
@@ -1075,4 +1102,28 @@ void iommu_debugfs_setup(void);
 static inline void iommu_debugfs_setup(void) {}
 #endif
 
+#ifdef CONFIG_IOMMU_SVA
+struct iommu_domain *
+iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm);
+void iommu_sva_free_domain(struct iommu_domain *domain);
+int iommu_sva_set_domain(struct iommu_domain *domain, struct device *dev,
+			 ioasid_t pasid);
+#else /* CONFIG_IOMMU_SVA */
+static inline struct iommu_domain *
+iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm)
+{
+	return ERR_PTR(-EINVAL);
+}
+
+static inline void iommu_sva_free_domain(struct iommu_domain *domain)
+{
+}
+
+static inline int iommu_sva_set_domain(struct iommu_domain *domain,
+				       struct device *dev, ioasid_t pasid)
+{
+	return -EINVAL;
+}
+#endif /* CONFIG_IOMMU_SVA */
+
 #endif /* __LINUX_IOMMU_H */
diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
index 8909ea1094e3..1be21e6b93ec 100644
--- a/drivers/iommu/iommu-sva-lib.h
+++ b/drivers/iommu/iommu-sva-lib.h
@@ -7,6 +7,7 @@
 
 #include <linux/ioasid.h>
 #include <linux/mm_types.h>
+#include <linux/iommu.h>
 
 int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);
 struct mm_struct *iommu_sva_find(ioasid_t pasid);
@@ -16,6 +17,20 @@ struct device;
 struct iommu_fault;
 struct iopf_queue;
 
+struct iommu_sva_domain {
+	struct iommu_domain	domain;
+	struct mm_struct	*mm;
+};
+
+#define to_sva_domain(d) container_of_safe(d, struct iommu_sva_domain, domain)
+
+static inline struct mm_struct *domain_to_mm(struct iommu_domain *domain)
+{
+	struct iommu_sva_domain *sva_domain = to_sva_domain(domain);
+
+	return sva_domain->mm;
+}
+
 #ifdef CONFIG_IOMMU_SVA
 int iommu_queue_iopf(struct iommu_fault *fault, void *cookie);
 
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
index 106506143896..210c376f6043 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -69,3 +69,51 @@ struct mm_struct *iommu_sva_find(ioasid_t pasid)
 	return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
 }
 EXPORT_SYMBOL_GPL(iommu_sva_find);
+
+/*
+ * IOMMU SVA driver-oriented interfaces
+ */
+struct iommu_domain *
+iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm)
+{
+	struct iommu_sva_domain *sva_domain;
+	struct iommu_domain *domain;
+
+	if (!bus->iommu_ops || !bus->iommu_ops->sva_domain_ops)
+		return ERR_PTR(-ENODEV);
+
+	sva_domain = kzalloc(sizeof(*sva_domain), GFP_KERNEL);
+	if (!sva_domain)
+		return ERR_PTR(-ENOMEM);
+
+	mmgrab(mm);
+	sva_domain->mm = mm;
+
+	domain = &sva_domain->domain;
+	domain->type = IOMMU_DOMAIN_SVA;
+	domain->ops = bus->iommu_ops->sva_domain_ops;
+
+	return domain;
+}
+
+void iommu_sva_free_domain(struct iommu_domain *domain)
+{
+	struct iommu_sva_domain *sva_domain = to_sva_domain(domain);
+
+	mmdrop(sva_domain->mm);
+	kfree(sva_domain);
+}
+
+int iommu_sva_set_domain(struct iommu_domain *domain, struct device *dev,
+			 ioasid_t pasid)
+{
+	struct bus_type *bus = dev->bus;
+
+	if (!bus || !bus->iommu_ops || !bus->iommu_ops->sva_domain_ops)
+		return -ENODEV;
+
+	if (domain->ops != bus->iommu_ops->sva_domain_ops)
+		return -EINVAL;
+
+	return iommu_set_device_pasid(domain, dev, pasid);
+}
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 9955f58bd08c..789816e4b9d6 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -38,6 +38,7 @@ struct iommu_group {
 	struct kobject kobj;
 	struct kobject *devices_kobj;
 	struct list_head devices;
+	struct xarray pasid_array;
 	struct mutex mutex;
 	void *iommu_data;
 	void (*iommu_data_release)(void *iommu_data);
@@ -640,6 +641,7 @@ struct iommu_group *iommu_group_alloc(void)
 	mutex_init(&group->mutex);
 	INIT_LIST_HEAD(&group->devices);
 	INIT_LIST_HEAD(&group->entry);
+	xa_init(&group->pasid_array);
 
 	ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL);
 	if (ret < 0) {
@@ -3251,3 +3253,72 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 	return user;
 }
 EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);
+
+static bool device_group_immutable_singleton(struct device *dev)
+{
+	struct iommu_group *group = iommu_group_get(dev);
+	int count;
+
+	if (!group)
+		return false;
+
+	mutex_lock(&group->mutex);
+	count = iommu_group_device_count(group);
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+
+	if (count != 1)
+		return false;
+
+	/*
+	 * The PCI device could be considered to be fully isolated if all
+	 * devices on the path from the device to the host-PCI bridge are
+	 * protected from peer-to-peer DMA by ACS.
+	 */
+	if (dev_is_pci(dev))
+		return pci_acs_path_enabled(to_pci_dev(dev), NULL,
+					    REQ_ACS_FLAGS);
+
+	return true;
+}
+
+int iommu_set_device_pasid(struct iommu_domain *domain, struct device *dev,
+			   ioasid_t pasid)
+{
+	struct iommu_group *group;
+	int ret = -EBUSY;
+	void *curr;
+
+	if (!domain->ops->set_dev_pasid)
+		return -EOPNOTSUPP;
+
+	if (!device_group_immutable_singleton(dev))
+		return -EINVAL;
+
+	group = iommu_group_get(dev);
+	mutex_lock(&group->mutex);
+	curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL);
+	if (curr)
+		goto out_unlock;
+	ret = domain->ops->set_dev_pasid(domain, dev, pasid);
+	if (ret)
+		xa_erase(&group->pasid_array, pasid);
+out_unlock:
+	mutex_unlock(&group->mutex);
+	iommu_group_put(group);
+
+	return ret;
+}
+
+void iommu_block_device_pasid(struct iommu_domain *domain, struct device *dev,
+			      ioasid_t pasid)
+{
+	struct iommu_group *group = iommu_group_get(dev);
+
+	mutex_lock(&group->mutex);
+	domain->ops->block_dev_pasid(domain, dev, pasid);
+	xa_erase(&group->pasid_array, pasid);
+	mutex_unlock(&group->mutex);
+
+	iommu_group_put(group);
+}
-- 
2.25.1