Re: [PATCH v6 2/6] iommufd: Add IOMMU_HWPT_INVALIDATE

Yi Liu <yi.l.liu@xxxxxxxxx> · Thu, 7 Dec 2023 14:59:17 +0800

On 2023/11/17 21:07, Yi Liu wrote:
In nested translation, the stage-1 page table is user-managed but cached
by the IOMMU hardware, so an update on present page table entries in the
stage-1 page table should be followed with a cache invalidation.

Add an IOMMU_HWPT_INVALIDATE ioctl to support such a cache invalidation.
It takes hwpt_id to specify the iommu_domain, and a multi-entry array to
support multiple invalidation requests in one ioctl.

Check cache_invalidate_user op in the iommufd_hw_pagetable_alloc_nested,
since all nested domains need that.

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/hw_pagetable.c    | 35 +++++++++++++++++++++++++
  drivers/iommu/iommufd/iommufd_private.h |  9 +++++++
  drivers/iommu/iommufd/main.c            |  3 +++
  include/uapi/linux/iommufd.h            | 35 +++++++++++++++++++++++++
  4 files changed, 82 insertions(+)

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 2abbeafdbd22..367459d92f69 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -238,6 +238,11 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
  		rc = -EINVAL;
  		goto out_abort;
  	}
+	/* Driver is buggy by missing cache_invalidate_user in domain_ops */
+	if (WARN_ON_ONCE(!hwpt->domain->ops->cache_invalidate_user)) {
+		rc = -EINVAL;
+		goto out_abort;
+	}
  	return hwpt_nested;
  
  out_abort:
@@ -370,4 +375,34 @@ int iommufd_hwpt_get_dirty_bitmap(struct iommufd_ucmd *ucmd)
  
  	iommufd_put_object(&hwpt_paging->common.obj);
  	return rc;
+};
+
+int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_hwpt_invalidate *cmd = ucmd->cmd;
+	struct iommu_user_data_array data_array = {
+		.type = cmd->req_type,
+		.uptr = u64_to_user_ptr(cmd->reqs_uptr),
+		.entry_len = cmd->req_len,
+		.entry_num = cmd->req_num,
+	};
+	struct iommufd_hw_pagetable *hwpt;
+	int rc = 0;
+
+	if (cmd->req_type == IOMMU_HWPT_DATA_NONE)
+		return -EINVAL;
+	if (!cmd->reqs_uptr || !cmd->req_len || !cmd->req_num)
+		return -EINVAL;
+
+	hwpt = iommufd_hw_pagetable_get_nested(ucmd, cmd->hwpt_id);
+	if (IS_ERR(hwpt))
+		return PTR_ERR(hwpt);
+
+	rc = hwpt->domain->ops->cache_invalidate_user(hwpt->domain, &data_array,
+						      &cmd->out_driver_error_code);
+	cmd->req_num = data_array.entry_num;
+	if (iommufd_ucmd_respond(ucmd, sizeof(*cmd)))
+		return -EFAULT;
+	iommufd_put_object(&hwpt->obj);
+	return rc;
  }
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index a74cfefffbc6..160521800d9b 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -301,6 +301,7 @@ void iommufd_hwpt_paging_abort(struct iommufd_object *obj);
  void iommufd_hwpt_nested_destroy(struct iommufd_object *obj);
  void iommufd_hwpt_nested_abort(struct iommufd_object *obj);
  int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd);
+int iommufd_hwpt_invalidate(struct iommufd_ucmd *ucmd);
  
  static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
  					    struct iommufd_hw_pagetable *hwpt)
@@ -318,6 +319,14 @@ static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
  	refcount_dec(&hwpt->obj.users);
  }
  
+static inline struct iommufd_hw_pagetable *
+iommufd_hw_pagetable_get_nested(struct iommufd_ucmd *ucmd, u32 id)
+{
+	return container_of(iommufd_get_object(ucmd->ictx, id,
+					       IOMMUFD_OBJ_HWPT_NESTED),
+			    struct iommufd_hw_pagetable, obj);
+}
+
  struct iommufd_group {
  	struct kref ref;
  	struct mutex lock;
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 45b9d40773b1..6edef860f91c 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -309,6 +309,7 @@ union ucmd_buffer {
  	struct iommu_hwpt_alloc hwpt;
  	struct iommu_hwpt_get_dirty_bitmap get_dirty_bitmap;
  	struct iommu_hwpt_set_dirty_tracking set_dirty_tracking;
+	struct iommu_hwpt_invalidate cache;
  	struct iommu_ioas_alloc alloc;
  	struct iommu_ioas_allow_iovas allow_iovas;
  	struct iommu_ioas_copy ioas_copy;
@@ -348,6 +349,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
  		 struct iommu_hwpt_get_dirty_bitmap, data),
  	IOCTL_OP(IOMMU_HWPT_SET_DIRTY_TRACKING, iommufd_hwpt_set_dirty_tracking,
  		 struct iommu_hwpt_set_dirty_tracking, __reserved),
+	IOCTL_OP(IOMMU_HWPT_INVALIDATE, iommufd_hwpt_invalidate,
+		 struct iommu_hwpt_invalidate, out_driver_error_code),
  	IOCTL_OP(IOMMU_IOAS_ALLOC, iommufd_ioas_alloc_ioctl,
  		 struct iommu_ioas_alloc, out_ioas_id),
  	IOCTL_OP(IOMMU_IOAS_ALLOW_IOVAS, iommufd_ioas_allow_iovas,
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 0b2bc6252e2c..7f92cecc87d7 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -49,6 +49,7 @@ enum {
  	IOMMUFD_CMD_GET_HW_INFO,
  	IOMMUFD_CMD_HWPT_SET_DIRTY_TRACKING,
  	IOMMUFD_CMD_HWPT_GET_DIRTY_BITMAP,
+	IOMMUFD_CMD_HWPT_INVALIDATE,
  };
  
  /**
@@ -613,4 +614,38 @@ struct iommu_hwpt_get_dirty_bitmap {
  #define IOMMU_HWPT_GET_DIRTY_BITMAP _IO(IOMMUFD_TYPE, \
  					IOMMUFD_CMD_HWPT_GET_DIRTY_BITMAP)
  
+/**
+ * struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
+ * @size: sizeof(struct iommu_hwpt_invalidate)
+ * @hwpt_id: HWPT ID of a nested HWPT for cache invalidation
+ * @reqs_uptr: User pointer to an array having @req_num of cache invalidation
+ *             requests. The request entries in the array are of fixed width
+ *             @req_len, and contain a user data structure for invalidation
+ *             request specific to the given hardware page table.
+ * @req_type: One of enum iommu_hwpt_data_type, defining the data type of all
+ *            the entries in the invalidation request array. It should suit
+ *            with the data_type passed per the allocation of the hwpt pointed
+ *            by @hwpt_id.

@Jason and Kevin,

Here a check with you two. I had a conversation with Nic on the definition
of req_type here. It was added to support potential multiple kinds of cache
invalidation data types for a invalidating cache for a single hwpt type[1].
But we defined it as reusing the hwpt_data_type. In this way, it is not
able to support the potential case in[1]. is it? Shall we define a separate
enum for invalidation data types? And how can we let user know the
available invalidation data types for a hwpt type? Any idea?

[1] https://lore.kernel.org/linux-iommu/20231018163720.GA3952@xxxxxxxxxx/


+ * @req_len: Length (in bytes) of a request entry in the request array
+ * @req_num: Input the number of cache invalidation requests in the array.
+ *           Output the number of requests successfully handled by kernel.
+ * @out_driver_error_code: Report a driver speicifc error code upon failure.
+ *                         It's optional, driver has a choice to fill it or
+ *                         not.
+ *
+ * Invalidate the iommu cache for user-managed page table. Modifications on a
+ * user-managed page table should be followed by this operation to sync cache.
+ * Each ioctl can support one or more cache invalidation requests in the array
+ * that has a total size of @req_len * @req_num.
+ */
+struct iommu_hwpt_invalidate {
+	__u32 size;
+	__u32 hwpt_id;
+	__aligned_u64 reqs_uptr;
+	__u32 req_type;
+	__u32 req_len;
+	__u32 req_num;
+	__u32 out_driver_error_code;
+};
+#define IOMMU_HWPT_INVALIDATE _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_INVALIDATE)
  #endif

--
Regards,
Yi Liu







