Jason Gunthorpe <jgg@xxxxxxxx> pointed out that u64 VFIO ioctl struct fields have architecture-dependent alignment. iommufd already uses __aligned_u64 to avoid this problem. Reasons for using __aligned_u64 include avoiding potential information leaks due to architecture-specific holes in structs and 32-bit userspace on 64-bit kernel ioctl compatibility issues. See the __aligned_u64 typedef in <uapi/linux/types.h> for details. This series modifies the VFIO ioctl structs to use __aligned_u64. Some of the changes preserve the existing memory layout on all architectures, so I put them together into the first patch. The remaining patches are for structs where explanation is necessary about why changing the memory layout does not break the uapi. Stefan Hajnoczi (4): vfio: trivially use __aligned_u64 for ioctl structs vfio: use __aligned_u64 in struct vfio_device_gfx_plane_info vfio: use __aligned_u64 in struct vfio_iommu_type1_info vfio: use __aligned_u64 in struct vfio_device_ioeventfd include/uapi/linux/vfio.h | 27 +++++++++++++++------------ drivers/gpu/drm/i915/gvt/kvmgt.c | 4 +++- drivers/vfio/vfio_iommu_type1.c | 11 ++--------- samples/vfio-mdev/mbochs.c | 6 ++++-- samples/vfio-mdev/mdpy.c | 4 +++- 5 files changed, 27 insertions(+), 25 deletions(-) -- 2.41.0
