iommufd/viommu: Add IOMMU_VIOMMU_ALLOC ioctl

Add a new ioctl for user space to do a vIOMMU allocation. It must be based
on a nesting parent HWPT, so take its refcount.

IOMMU driver wanting to support vIOMMUs must define its IOMMU_VIOMMU_TYPE_
in the uAPI header and implement a viommu_alloc op in its iommu_ops.

Link: https://patch.msgid.link/r/dc2b8ba9ac935007beff07c1761c31cd097ed780.1730836219.git.nicolinc@nvidia.com
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 41b1a01e9293..302844136b02 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -52,6 +52,7 @@ enum {
 	IOMMUFD_CMD_HWPT_INVALIDATE = 0x8d,
 	IOMMUFD_CMD_FAULT_QUEUE_ALLOC = 0x8e,
 	IOMMUFD_CMD_IOAS_MAP_FILE = 0x8f,
+	IOMMUFD_CMD_VIOMMU_ALLOC = 0x90,
 };
 
 /**
@@ -822,4 +823,43 @@ struct iommu_fault_alloc {
 	__u32 out_fault_fd;
 };
 #define IOMMU_FAULT_QUEUE_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_FAULT_QUEUE_ALLOC)
+
+/**
+ * enum iommu_viommu_type - Virtual IOMMU Type
+ * @IOMMU_VIOMMU_TYPE_DEFAULT: Reserved for future use
+ */
+enum iommu_viommu_type {
+	IOMMU_VIOMMU_TYPE_DEFAULT = 0,
+};
+
+/**
+ * struct iommu_viommu_alloc - ioctl(IOMMU_VIOMMU_ALLOC)
+ * @size: sizeof(struct iommu_viommu_alloc)
+ * @flags: Must be 0
+ * @type: Type of the virtual IOMMU. Must be defined in enum iommu_viommu_type
+ * @dev_id: The device's physical IOMMU will be used to back the virtual IOMMU
+ * @hwpt_id: ID of a nesting parent HWPT to associate to
+ * @out_viommu_id: Output virtual IOMMU ID for the allocated object
+ *
+ * Allocate a virtual IOMMU object, representing the underlying physical IOMMU's
+ * virtualization support that is a security-isolated slice of the real IOMMU HW
+ * that is unique to a specific VM. Operations global to the IOMMU are connected
+ * to the vIOMMU, such as:
+ * - Security namespace for guest owned ID, e.g. guest-controlled cache tags
+ * - Non-device-affiliated event reporting, e.g. invalidation queue errors
+ * - Access to a sharable nesting parent pagetable across physical IOMMUs
+ * - Virtualization of various platforms IDs, e.g. RIDs and others
+ * - Delivery of paravirtualized invalidation
+ * - Direct assigned invalidation queues
+ * - Direct assigned interrupts
+ */
+struct iommu_viommu_alloc {
+	__u32 size;
+	__u32 flags;
+	__u32 type;
+	__u32 dev_id;
+	__u32 hwpt_id;
+	__u32 out_viommu_id;
+};
+#define IOMMU_VIOMMU_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_ALLOC)
 #endif