[PATCH v3 01/21] iommu: Add iommu_paging_domain_alloc() interface

Lu Baolu
2024-06-10T08:58:22Z

Commit <17de3f5fdd35> ("iommu: Retire bus ops") removes iommu ops from
bus. The iommu subsystem no longer relies on bus for operations. So the
bus parameter in iommu_domain_alloc() is no longer relevant.

Add a new interface named iommu_paging_domain_alloc(), which explicitly
indicates the allocation of a paging domain for DMA managed by a kernel
driver. The new interface takes a device pointer as its parameter, that
better aligns with the current iommu subsystem.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
include/linux/iommu.h | 6 ++++++
drivers/iommu/iommu.c | 20 ++++++++++++++++++++
2 files changed, 26 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 7bc8dff7cf6d..46f1348f1f0a 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -780,6 +780,7 @@ extern bool iommu_present(const struct bus_type *bus);
extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);
extern bool iommu_group_has_isolated_msi(struct iommu_group *group);
extern struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus);
+struct iommu_domain *iommu_paging_domain_alloc(struct device *dev);
extern void iommu_domain_free(struct iommu_domain *domain);
extern int iommu_attach_device(struct iommu_domain *domain,
struct device *dev);
@@ -1086,6 +1087,11 @@ static inline struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus
return NULL;
}

+static inline struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
+{
+ return ERR_PTR(-ENODEV);
+}
+
static inline void iommu_domain_free(struct iommu_domain *domain)
{
}
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 9df7cc75c1bc..e03c71a34347 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2016,6 +2016,10 @@ static int __iommu_domain_alloc_dev(struct device *dev, void *data)
return 0;
}

+/*
+ * The iommu ops in bus has been retired. Do not use this interface in
+ * new drivers.
+ */
struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
{
const struct iommu_ops *ops = NULL;
@@ -2032,6 +2036,22 @@ struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
}
EXPORT_SYMBOL_GPL(iommu_domain_alloc);

+/**
+ * iommu_paging_domain_alloc() - Allocate a paging domain
+ * @dev: device for which the domain is allocated
+ *
+ * Allocate a paging domain which will be managed by a kernel driver. Return
+ * allocated domain if successful, or a ERR pointer for failure.
+ */
+struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
+{
+ if (!dev_has_iommu(dev))
+ return ERR_PTR(-ENODEV);
+
+ return __iommu_domain_alloc(dev_iommu_ops(dev), dev, IOMMU_DOMAIN_UNMANAGED);
+}
+EXPORT_SYMBOL_GPL(iommu_paging_domain_alloc);
+
void iommu_domain_free(struct iommu_domain *domain)
{
if (domain->type == IOMMU_DOMAIN_SVA)
--
2.34.1