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SubjectRe: [PATCH v7 2/7] iommu/uapi: Add argsz for user filled data
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Hi,

On 7/30/20 2:21 AM, Jacob Pan wrote:
> As IOMMU UAPI gets extended, user data size may increase. To support
> backward compatibiliy, this patch introduces a size field to each UAPI
s/compatibiliy/compatibility
> data structures. It is *always* the responsibility for the user to fill in
> the correct size. Padding fields are adjusted to ensure 8 byte alignment.
>
> Specific scenarios for user data handling are documented in:
> Documentation/userspace-api/iommu.rst

you may mention the struct version does not need to be incremented as no
IOCTL uses the structs yet.
>
> 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 | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index e907b7091a46..d5e9014f690e 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 */
> @@ -255,7 +259,7 @@ struct iommu_cache_invalidate_info {
> #define IOMMU_CACHE_INV_TYPE_NR (3)
> __u8 cache;
> __u8 granularity;
> - __u8 padding[2];
> + __u8 padding[6];
> union {
> struct iommu_inv_pasid_info pasid_info;
> struct iommu_inv_addr_info addr_info;
> @@ -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
> @@ -309,17 +314,18 @@ 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
> __u32 format;
> + __u32 addr_width;
> #define IOMMU_SVA_GPASID_VAL (1 << 0) /* guest PASID valid */
> __u64 flags;
> __u64 gpgd;
> __u64 hpasid;
> __u64 gpasid;
> - __u32 addr_width;
> - __u8 padding[12];
> + __u8 padding[8];
> /* Vendor specific data */
> union {
> struct iommu_gpasid_bind_data_vtd vtd;
>
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Thanks

Eric

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