[PATCH kernel] vfio: Add explicit alignments in vfio_iommu_spapr_tce_create

[PATCH kernel] vfio: Add explicit alignments in vfio_iommu_spapr_tce_create

[Alexey Kardashevskiy]

The vfio_iommu_spapr_tce_create struct has 4x32bit and 2x64bit fields
which should have resulted in sizeof(fio_iommu_spapr_tce_create) equal
to 32 bytes. However due to the gcc's default alignment, the actual
size of this struct is 40 bytes.

This fills gaps with __resv1/2 fields.

This should not cause any change in behavior.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 include/uapi/linux/vfio.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 9fd7b5d..d117233 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -568,8 +568,10 @@ struct vfio_iommu_spapr_tce_create {
 	__u32 flags;
 	/* in */
 	__u32 page_shift;
+	__u32 __resv1;
 	__u64 window_size;
 	__u32 levels;
+	__u32 __resv2;
 	/* out */
 	__u64 start_addr;
 };
-- 
2.5.0.rc3

Re: [PATCH kernel] vfio: Add explicit alignments in vfio_iommu_spapr_tce_create

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 1280 bytes --]

On Fri, Dec 18, 2015 at 12:35:47PM +1100, Alexey Kardashevskiy wrote:
> The vfio_iommu_spapr_tce_create struct has 4x32bit and 2x64bit fields
> which should have resulted in sizeof(fio_iommu_spapr_tce_create) equal
> to 32 bytes. However due to the gcc's default alignment, the actual
> size of this struct is 40 bytes.
> 
> This fills gaps with __resv1/2 fields.
> 
> This should not cause any change in behavior.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Oops, that was a bit sloppy.  Oh well.

Acked-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  include/uapi/linux/vfio.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 9fd7b5d..d117233 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -568,8 +568,10 @@ struct vfio_iommu_spapr_tce_create {
>  	__u32 flags;
>  	/* in */
>  	__u32 page_shift;
> +	__u32 __resv1;
>  	__u64 window_size;
>  	__u32 levels;
> +	__u32 __resv2;
>  	/* out */
>  	__u64 start_addr;
>  };

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

Re: [PATCH kernel] vfio: Add explicit alignments in vfio_iommu_spapr_tce_create

[Alex Williamson]

On Fri, 2015-12-18 at 12:35 +1100, Alexey Kardashevskiy wrote:
> The vfio_iommu_spapr_tce_create struct has 4x32bit and 2x64bit fields
> which should have resulted in sizeof(fio_iommu_spapr_tce_create)
> equal
> to 32 bytes. However due to the gcc's default alignment, the actual
> size of this struct is 40 bytes.
> 
> This fills gaps with __resv1/2 fields.
> 
> This should not cause any change in behavior.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---

Applied to next for v4.5 with David's ack.  Thanks!

Alex

>  include/uapi/linux/vfio.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 9fd7b5d..d117233 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -568,8 +568,10 @@ struct vfio_iommu_spapr_tce_create {
>  	__u32 flags;
>  	/* in */
>  	__u32 page_shift;
> +	__u32 __resv1;
>  	__u64 window_size;
>  	__u32 levels;
> +	__u32 __resv2;
>  	/* out */
>  	__u64 start_addr;
>  };