[PATCH v4 2/5] iommu/uapi: Add argsz for user filled data

Jacob Pan
2020-07-07T23:37:25Z

As IOMMU UAPI gets extended, user data size may increase. To support
backward compatibiliy, this patch introduces a size field to each UAPI
data structures. It is *always* the responsibility for the user to fill in
the correct size.

Specific scenarios for user data handling are documented in:
Documentation/userspace-api/iommu.rst

Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
include/uapi/linux/iommu.h | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
index e907b7091a46..303f148a5cd7 100644
--- a/include/uapi/linux/iommu.h
+++ b/include/uapi/linux/iommu.h
@@ -135,6 +135,7 @@ enum iommu_page_response_code {

/**
* struct iommu_page_response - Generic page response information
+ * @argsz: User filled size of this data
* @version: API version of this structure
* @flags: encodes whether the corresponding fields are valid
* (IOMMU_FAULT_PAGE_RESPONSE_* values)
@@ -143,6 +144,7 @@ enum iommu_page_response_code {
* @code: response code from &enum iommu_page_response_code
*/
struct iommu_page_response {
+ __u32 argsz;
#define IOMMU_PAGE_RESP_VERSION_1 1
__u32 version;
#define IOMMU_PAGE_RESP_PASID_VALID (1 << 0)
@@ -218,6 +220,7 @@ struct iommu_inv_pasid_info {
/**
* struct iommu_cache_invalidate_info - First level/stage invalidation
* information
+ * @argsz: User filled size of this data
* @version: API version of this structure
* @cache: bitfield that allows to select which caches to invalidate
* @granularity: defines the lowest granularity used for the invalidation:
@@ -246,6 +249,7 @@ struct iommu_inv_pasid_info {
* must support the used granularity.
*/
struct iommu_cache_invalidate_info {
+ __u32 argsz;
#define IOMMU_CACHE_INVALIDATE_INFO_VERSION_1 1
__u32 version;
/* IOMMU paging structure cache */
@@ -292,6 +296,7 @@ struct iommu_gpasid_bind_data_vtd {

/**
* struct iommu_gpasid_bind_data - Information about device and guest PASID binding
+ * @argsz: User filled size of this data
* @version: Version of this data structure
* @format: PASID table entry format
* @flags: Additional information on guest bind request
@@ -309,6 +314,7 @@ struct iommu_gpasid_bind_data_vtd {
* PASID to host PASID based on this bind data.
*/
struct iommu_gpasid_bind_data {
+ __u32 argsz;
#define IOMMU_GPASID_BIND_VERSION_1 1
__u32 version;
#define IOMMU_PASID_FORMAT_INTEL_VTD 1
--
2.7.4