linux-kernel - [PATCH v1 03/16] iommu: Add iommu_copy_struct_to

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Message-ID: <65b51f57d08069c9da909586faf4e73d247a54f5.1744353300.git.nicolinc@nvidia.com>
Date: Thu, 10 Apr 2025 23:37:42 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: <jgg@...dia.com>, <kevin.tian@...el.com>, <corbet@....net>,
	<will@...nel.org>
CC: <robin.murphy@....com>, <joro@...tes.org>, <thierry.reding@...il.com>,
	<vdumpa@...dia.com>, <jonathanh@...dia.com>, <shuah@...nel.org>,
	<praan@...gle.com>, <nathan@...nel.org>, <peterz@...radead.org>,
	<yi.l.liu@...el.com>, <jsnitsel@...hat.com>, <mshavit@...gle.com>,
	<zhangzekun11@...wei.com>, <iommu@...ts.linux.dev>,
	<linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-tegra@...r.kernel.org>,
	<linux-kselftest@...r.kernel.org>, <patches@...ts.linux.dev>
Subject: [PATCH v1 03/16] iommu: Add iommu_copy_struct_to_user helper

Similar to the iommu_copy_struct_from_user helper receiving data from the
user space, add an iommu_copy_struct_to_user helper to report output data
back to the user space data pointer.

Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
 include/linux/iommu.h | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ebde19aa3c28..ffb00054da33 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -562,6 +562,46 @@ iommu_copy_struct_from_full_user_array(void *kdst, size_t kdst_entry_size,
 	return 0;
 }
 
+/**
+ * __iommu_copy_struct_to_user - Report iommu driver specific user space data
+ * @dst_data: Pointer to a struct iommu_user_data for user space data location
+ * @src_data: Pointer to an iommu driver specific user data that is defined in
+ *            include/uapi/linux/iommufd.h
+ * @data_type: The data type of the @dst_data. Must match with @src_data.type
+ * @data_len: Length of current user data structure, i.e. sizeof(struct _src)
+ * @min_len: Initial length of user data structure for backward compatibility.
+ *           This should be offsetofend using the last member in the user data
+ *           struct that was initially added to include/uapi/linux/iommufd.h
+ */
+static inline int
+__iommu_copy_struct_to_user(const struct iommu_user_data *dst_data,
+			    void *src_data, unsigned int data_type,
+			    size_t data_len, size_t min_len)
+{
+	if (dst_data->type != data_type)
+		return -EINVAL;
+	if (WARN_ON(!dst_data || !src_data))
+		return -EINVAL;
+	if (dst_data->len < min_len || data_len < dst_data->len)
+		return -EINVAL;
+	return copy_struct_to_user(dst_data->uptr, dst_data->len, src_data,
+				   data_len, NULL);
+}
+
+/**
+ * iommu_copy_struct_to_user - Report iommu driver specific user space data
+ * @user_data: Pointer to a struct iommu_user_data for user space data location
+ * @ksrc: Pointer to an iommu driver specific user data that is defined in
+ *        include/uapi/linux/iommufd.h
+ * @data_type: The data type of the @ksrc. Must match with @user_data->type
+ * @min_last: The last memember of the data structure @ksrc points in the
+ *            initial version.
+ * Return 0 for success, otherwise -error.
+ */
+#define iommu_copy_struct_to_user(user_data, ksrc, data_type, min_last)        \
+	__iommu_copy_struct_to_user(user_data, ksrc, data_type, sizeof(*ksrc), \
+				    offsetofend(typeof(*ksrc), min_last))
+
 /**
  * struct iommu_ops - iommu ops and capabilities
  * @capable: check capability
-- 
2.43.0