[PATCH v6 1/6] iommu: Add cache_invalidate_user op

[Yi Liu]

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

The updates of the PTEs in the nested page table will be propagated to the
hardware caches on both IOMMU (IOTLB) and devices (DevTLB/ATC).

Add a new domain op cache_invalidate_user for the userspace to flush the
hardware caches for a nested domain through iommufd. No wrapper for it,
as it's only supposed to be used by iommufd. Then, pass in invalidation
requests in form of a user data array conatining a number of invalidation
data entries.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 include/linux/iommu.h | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ec289c1016f5..0c1ff7fe4fa1 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -284,6 +284,24 @@ struct iommu_user_data {
 	size_t len;
 };
 
+/**
+ * struct iommu_user_data_array - iommu driver specific user space data array
+ * @type: The data type of all the entries in the user buffer array
+ * @uptr: Pointer to the user buffer array for copy_from_user()
+ * @entry_len: The fixed-width length of a entry in the array, in bytes
+ * @entry_num: The number of total entries in the array
+ *
+ * A array having a @entry_num number of @entry_len sized entries, each entry is
+ * user space data, an uAPI defined in include/uapi/linux/iommufd.h where @type
+ * is also defined as enum iommu_xyz_data_type.
+ */
+struct iommu_user_data_array {
+	unsigned int type;
+	void __user *uptr;
+	size_t entry_len;
+	int entry_num;
+};
+
 /**
  * __iommu_copy_struct_from_user - Copy iommu driver specific user space data
  * @dst_data: Pointer to an iommu driver specific user data that is defined in
@@ -440,6 +458,15 @@ struct iommu_ops {
  * @iotlb_sync_map: Sync mappings created recently using @map to the hardware
  * @iotlb_sync: Flush all queued ranges from the hardware TLBs and empty flush
  *            queue
+ * @cache_invalidate_user: Flush hardware cache for user space IO page table.
+ *                         The @domain must be IOMMU_DOMAIN_NESTED. The @array
+ *                         passes in the cache invalidation requests, in form
+ *                         of a driver data structure. The driver must update
+ *                         array->entry_num to report the number of handled
+ *                         invalidation requests. The 32-bit @error_code can
+ *                         forward a driver specific error code to user space.
+ *                         Both the driver data structure and the error code
+ *                         must be defined in include/uapi/linux/iommufd.h
  * @iova_to_phys: translate iova to physical address
  * @enforce_cache_coherency: Prevent any kind of DMA from bypassing IOMMU_CACHE,
  *                           including no-snoop TLPs on PCIe or other platform
@@ -465,6 +492,9 @@ struct iommu_domain_ops {
 			      size_t size);
 	void (*iotlb_sync)(struct iommu_domain *domain,
 			   struct iommu_iotlb_gather *iotlb_gather);
+	int (*cache_invalidate_user)(struct iommu_domain *domain,
+				     struct iommu_user_data_array *array,
+				     u32 *error_code);
 
 	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain,
 				    dma_addr_t iova);
-- 
2.34.1