Re: [PATCH v5 2/5] iommu/uapi: Add argsz for user filled data

Jacob Pan
2020-07-21T01:45:53Z

On Fri, 17 Jul 2020 15:44:23 +0200
Auger Eric <eric.auger@redhat.com> wrote:

> Hi Jacob,
>
> On 7/16/20 8:45 PM, 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 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
> >
> > 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
> Don't you need to incr the version for all the modified structs?
not literal "flags" but @cache and @granularity are flags in reality. I
think that is OK. I also updated document to say "flags or equivalent".

> > __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;
> so there is no "flags" field in this struct. Is it OK?
> > /* 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;
> >
> Thanks
>
> Eric
>

[Jacob Pan]