[PATCH 08/12] iommufd/device: Report supported hwpt_types

[Yi Liu]

This provides a way for userspace to probe the supported hwpt data
types by kernel. Currently, kernel only supports IOMMU_HWPT_TYPE_DEFAULT,
new types would be added per vendor drivers' extension.

Userspace that wants to allocate hw_pagetable with user data should check
this. While for the allocation without user data, no need for it. It is
supported by default.

Co-developed-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 drivers/iommu/iommufd/device.c          |  1 +
 drivers/iommu/iommufd/hw_pagetable.c    | 18 +++++++++++++++---
 drivers/iommu/iommufd/iommufd_private.h |  2 ++
 drivers/iommu/iommufd/main.c            |  2 +-
 include/uapi/linux/iommufd.h            |  8 ++++++++
 5 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 19cd6df46c6a..0328071dcac1 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -322,6 +322,7 @@ int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd)
 
 	cmd->out_data_type = ops->driver_type;
 	cmd->data_len = length;
+	cmd->out_hwpt_type_bitmap = iommufd_hwpt_type_bitmaps[ops->driver_type];
 
 	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
 
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 67facca98de1..160712256c64 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -173,6 +173,14 @@ static const size_t iommufd_hwpt_alloc_data_size[] = {
 	[IOMMU_HWPT_TYPE_DEFAULT] = 0,
 };
 
+/*
+ * bitmaps of supported hwpt types of by underlying iommu, indexed
+ * by ops->driver_type which is one of enum iommu_hw_info_type.
+ */
+const u64 iommufd_hwpt_type_bitmaps[] =  {
+	[IOMMU_HW_INFO_TYPE_DEFAULT] = BIT_ULL(IOMMU_HWPT_TYPE_DEFAULT),
+};
+
 int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 {
 	struct iommu_hwpt_alloc *cmd = ucmd->cmd;
@@ -182,7 +190,7 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 	struct iommufd_ioas *ioas;
 	const struct iommu_ops *ops;
 	void *data = NULL;
-	u32 klen;
+	u32 driver_type, klen;
 	int rc;
 
 	if (cmd->__reserved || cmd->flags)
@@ -198,8 +206,12 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 		goto out_put_idev;
 	}
 
-	/* Only support IOMMU_HWPT_TYPE_DEFAULT for now */
-	if (cmd->data_type != IOMMU_HWPT_TYPE_DEFAULT) {
+	driver_type = ops->driver_type;
+
+	/* data_type should be a supported type by the driver */
+	if (WARN_ON(driver_type >= ARRAY_SIZE(iommufd_hwpt_type_bitmaps)) ||
+	    !((1 << cmd->data_type) &
+			iommufd_hwpt_type_bitmaps[driver_type])) {
 		rc = -EINVAL;
 		goto out_put_idev;
 	}
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index d879264d1acf..164ccfc2e6e0 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -321,6 +321,8 @@ iommufd_get_device(struct iommufd_ucmd *ucmd, u32 id)
 void iommufd_device_destroy(struct iommufd_object *obj);
 int iommufd_device_get_hw_info(struct iommufd_ucmd *ucmd);
 
+extern const u64 iommufd_hwpt_type_bitmaps[];
+
 struct iommufd_access {
 	struct iommufd_object obj;
 	struct iommufd_ctx *ictx;
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 2cf45f65b637..7ec3ceac01b3 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -298,7 +298,7 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 	IOCTL_OP(IOMMU_HWPT_ALLOC, iommufd_hwpt_alloc, struct iommu_hwpt_alloc,
 		 data_uptr),
 	IOCTL_OP(IOMMU_DEVICE_GET_HW_INFO, iommufd_device_get_hw_info,
-		 struct iommu_hw_info, __reserved),
+		 struct iommu_hw_info, out_hwpt_type_bitmap),
 	IOCTL_OP(IOMMU_HWPT_INVALIDATE, iommufd_hwpt_invalidate,
 		 struct iommu_hwpt_invalidate, data_uptr),
 	IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl,
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index d0962c41f8d6..e2eff9c56ab3 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -421,6 +421,8 @@ enum iommu_hw_info_type {
  * @out_data_type: Output the iommu hardware info type, it is one of
  *                 enum iommu_hw_info_type.
  * @__reserved: Must be 0
+ * @out_hwpt_type_bitmap: Output the supported page table type. Each
+ *                        bit is defined in enum iommu_hwpt_type.
  *
  * Query the hardware iommu information for given device which has been
  * bound to iommufd. @data_len is the size of the buffer which captures
@@ -435,6 +437,11 @@ enum iommu_hw_info_type {
  * The @out_data_type will be filled if the ioctl succeeds. It would
  * be used to decode the data filled in the buffer pointed by @data_ptr.
  *
+ * @out_hwpt_type_bitmap reports the supported hwpt types. This differs
+ * per the @out_data_type. Userspace should check it before allocating a
+ * user-managed hw_pagetable with user data, unless it allocates a default
+ * hw_pagetable that does not need user data.
+ *
  * This is only available for the physical devices bound to iommufd as
  * only physical devices can have hardware IOMMU.
  */
@@ -446,6 +453,7 @@ struct iommu_hw_info {
 	__aligned_u64 data_ptr;
 	__u32 out_data_type;
 	__u32 __reserved;
+	__aligned_u64 out_hwpt_type_bitmap;
 };
 #define IOMMU_DEVICE_GET_HW_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DEVICE_GET_HW_INFO)
 
-- 
2.34.1