[v3,0/1] virtio_bt: Fix alignment in configuration struct

Message

Igor Skalkin Oct. 18, 2022, 7:19 p.m. UTC

According to specification [1], "For the device-specific configuration
space, the driver MUST use 8 bit wide accesses for 8 bit wide fields,
16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide
and aligned accesses for 32 and 64 bit wide fields.".

Current version of the configuration structure has non-aligned 16bit
fields.

This patch adds a second, aligned  version of the configuration structure
and a new feature bit indicating that this version is being used.

[1] https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.pdf

Changes in v3:
  v2 had been sent from the wrong address, fixed.
Changes in v2:
  The first version of this patch just changed the configuration
  structure in uapi/linux/virtio_bt.h
  This can not be done, because it will break the userspace, so the
  second version offers a less radical approach - it introduces a new
  feature bit and a new configuration structure that both the device
  and the driver will use if this bit is negotiated.

Igor Skalkin (1):
  virtio_bt: Fix alignment in configuration struct

 drivers/bluetooth/virtio_bt.c  | 16 +++++++++++++---
 include/uapi/linux/virtio_bt.h |  8 ++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

--
2.37.2


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Comments

Igor Skalkin Oct. 24, 2022, 1:40 p.m. UTC | #1

According to specification [1], "For the device-specific configuration
space, the driver MUST use 8 bit wide accesses for 8 bit wide fields,
16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide
and aligned accesses for 32 and 64 bit wide fields.".

Current version of the configuration structure has non-aligned 16bit
fields.

This patch adds a second, aligned  version of the configuration structure
and a new feature bit indicating that this version is being used.

[1] https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.pdf

Changes in v4:
  v3 was corrupted by our smtp server.
Changes in v3:
  v2 had been sent from the wrong address, fixed.
Changes in v2:
  The first version of this patch just changed the configuration
  structure in uapi/linux/virtio_bt.h
  This can not be done, because it will break the userspace, so the
  second version offers a less radical approach - it introduces a new
  feature bit and a new configuration structure that both the device
  and the driver will use if this bit is negotiated.

Igor Skalkin (1):
  virtio_bt: Fix alignment in configuration struct

 drivers/bluetooth/virtio_bt.c  | 16 +++++++++++++---
 include/uapi/linux/virtio_bt.h |  8 ++++++++
 2 files changed, 21 insertions(+), 3 deletions(-)

Michael S. Tsirkin Oct. 25, 2022, 4:04 a.m. UTC | #2

On Mon, Oct 24, 2022 at 03:40:32PM +0200, Igor Skalkin wrote:
> According to specification [1], "For the device-specific configuration
> space, the driver MUST use 8 bit wide accesses for 8 bit wide fields,
> 16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide
> and aligned accesses for 32 and 64 bit wide fields.".
> 
> Current version of the configuration structure has non-aligned 16bit
> fields.
> 
> This patch adds a second, aligned  version of the configuration structure
> and a new feature bit indicating that this version is being used.


subject should be v4 but besides that, ok.
Will a spec patch be forthcoming?

> [1] https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.pdf
> 
> Changes in v4:
>   v3 was corrupted by our smtp server.
> Changes in v3:
>   v2 had been sent from the wrong address, fixed.
> Changes in v2:
>   The first version of this patch just changed the configuration
>   structure in uapi/linux/virtio_bt.h
>   This can not be done, because it will break the userspace, so the
>   second version offers a less radical approach - it introduces a new
>   feature bit and a new configuration structure that both the device
>   and the driver will use if this bit is negotiated.
> 
> Igor Skalkin (1):
>   virtio_bt: Fix alignment in configuration struct
> 
>  drivers/bluetooth/virtio_bt.c  | 16 +++++++++++++---
>  include/uapi/linux/virtio_bt.h |  8 ++++++++
>  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> -- 
> 2.37.2