[PATCH RFC v2 1/3] iommu: Add set/unset_dev_data_user ops

Nicolin Chen
2023-04-20T07:49:02Z

The device behind an IOMMU might be used in the user space by a VM. So, it
might have some user space data. For example, a device behind an SMMU has
a static stream ID. In a virtualization use case, both a host environment
and a guest environment have their own Stream IDs. A link (a lookup table)
between the physical Stream ID and the virtual (user) Stream ID is needed
when the host handles the user cache invalidation commands.

Add a pair of new ops to allow user space to forward user_data of a device
via iommufd.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
include/linux/iommu.h | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5c99aeaccd1d..c87f0f1527dd 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -257,6 +257,9 @@ struct iommu_iotlb_gather {
* @remove_dev_pasid: Remove any translation configurations of a specific
* pasid, so that any DMA transactions with this pasid
* will be blocked by the hardware.
+ * @set/unset_dev_data_user: set/unset an iommu specific device data from user
+ * space. The user device data info will be used by
+ * the driver to take care of user space requests.
* @hw_info_type: One of enum iommu_hw_info_type defined in
* include/uapi/linux/iommufd.h. It is used to tag the type
* of data returned by .hw_info callback. The drivers that
@@ -303,6 +306,9 @@ struct iommu_ops {
int (*def_domain_type)(struct device *dev);
void (*remove_dev_pasid)(struct device *dev, ioasid_t pasid);

+ int (*set_dev_data_user)(struct device *dev, const void *user_data);
+ void (*unset_dev_data_user)(struct device *dev);
+
const struct iommu_domain_ops *default_domain_ops;
enum iommu_hw_info_type hw_info_type;
unsigned long long hwpt_type_bitmap;
--
2.40.0