[PATCH v4 01/15] iommu: Add API to request DMA domain for device

From: Lu Baolu
Date: Sat May 25 2019 - 01:52:04 EST


Normally during iommu probing a device, a default doamin will
be allocated and attached to the device. The domain type of
the default domain is statically defined, which results in a
situation where the allocated default domain isn't suitable
for the device due to some limitations. We already have API
iommu_request_dm_for_dev() to replace a DMA domain with an
identity one. This adds iommu_request_dma_domain_for_dev()
to request a dma domain if an allocated identity domain isn't
suitable for the device in question.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
drivers/iommu/iommu.c | 36 +++++++++++++++++++++++++-----------
include/linux/iommu.h | 6 ++++++
2 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index c09d60401778..03ba8406d1e4 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1910,10 +1910,10 @@ struct iommu_resv_region *iommu_alloc_resv_region(phys_addr_t start,
return region;
}

-/* Request that a device is direct mapped by the IOMMU */
-int iommu_request_dm_for_dev(struct device *dev)
+static int
+request_default_domain_for_dev(struct device *dev, unsigned long type)
{
- struct iommu_domain *dm_domain;
+ struct iommu_domain *domain;
struct iommu_group *group;
int ret;

@@ -1926,8 +1926,7 @@ int iommu_request_dm_for_dev(struct device *dev)

/* Check if the default domain is already direct mapped */
ret = 0;
- if (group->default_domain &&
- group->default_domain->type == IOMMU_DOMAIN_IDENTITY)
+ if (group->default_domain && group->default_domain->type == type)
goto out;

/* Don't change mappings of existing devices */
@@ -1937,23 +1936,26 @@ int iommu_request_dm_for_dev(struct device *dev)

/* Allocate a direct mapped domain */
ret = -ENOMEM;
- dm_domain = __iommu_domain_alloc(dev->bus, IOMMU_DOMAIN_IDENTITY);
- if (!dm_domain)
+ domain = __iommu_domain_alloc(dev->bus, type);
+ if (!domain)
goto out;

/* Attach the device to the domain */
- ret = __iommu_attach_group(dm_domain, group);
+ ret = __iommu_attach_group(domain, group);
if (ret) {
- iommu_domain_free(dm_domain);
+ iommu_domain_free(domain);
goto out;
}

+ iommu_group_create_direct_mappings(group, dev);
+
/* Make the direct mapped domain the default for this group */
if (group->default_domain)
iommu_domain_free(group->default_domain);
- group->default_domain = dm_domain;
+ group->default_domain = domain;

- dev_info(dev, "Using iommu direct mapping\n");
+ dev_info(dev, "Using iommu %s mapping\n",
+ type == IOMMU_DOMAIN_DMA ? "dma" : "direct");

ret = 0;
out:
@@ -1963,6 +1965,18 @@ int iommu_request_dm_for_dev(struct device *dev)
return ret;
}

+/* Request that a device is direct mapped by the IOMMU */
+int iommu_request_dm_for_dev(struct device *dev)
+{
+ return request_default_domain_for_dev(dev, IOMMU_DOMAIN_IDENTITY);
+}
+
+/* Request that a device can't be direct mapped by the IOMMU */
+int iommu_request_dma_domain_for_dev(struct device *dev)
+{
+ return request_default_domain_for_dev(dev, IOMMU_DOMAIN_DMA);
+}
+
const struct iommu_ops *iommu_ops_from_fwnode(struct fwnode_handle *fwnode)
{
const struct iommu_ops *ops = NULL;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 14a521f85f14..593a3411d860 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -368,6 +368,7 @@ extern void iommu_set_fault_handler(struct iommu_domain *domain,
extern void iommu_get_resv_regions(struct device *dev, struct list_head *list);
extern void iommu_put_resv_regions(struct device *dev, struct list_head *list);
extern int iommu_request_dm_for_dev(struct device *dev);
+extern int iommu_request_dma_domain_for_dev(struct device *dev);
extern struct iommu_resv_region *
iommu_alloc_resv_region(phys_addr_t start, size_t length, int prot,
enum iommu_resv_type type, gfp_t flags);
@@ -632,6 +633,11 @@ static inline int iommu_request_dm_for_dev(struct device *dev)
return -ENODEV;
}

+static inline int iommu_request_dma_domain_for_dev(struct device *dev)
+{
+ return -ENODEV;
+}
+
static inline int iommu_attach_group(struct iommu_domain *domain,
struct iommu_group *group)
{
--
2.17.1