Re: [RFC v2 5/5] vfio-ccw: Update documentation for csch/hsch

Cornelia Huck
2019-07-09T10:14:50Z

On Mon, 8 Jul 2019 16:10:38 -0400
Farhan Ali <alifm@linux.ibm.com> wrote:

> We now support CLEAR SUBCHANNEL and HALT SUBCHANNEL
> via ccw_cmd_region.
>

Thanks, I forgot about this.

Fixes: d5afd5d135c8 ("vfio-ccw: add handling for async channel instructions")

> Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
> ---
> Documentation/s390/vfio-ccw.rst | 31 ++++++++++++++++++++++++++++---
> 1 file changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/s390/vfio-ccw.rst b/Documentation/s390/vfio-ccw.rst
> index 1f6d0b5..40e4110 100644
> --- a/Documentation/s390/vfio-ccw.rst
> +++ b/Documentation/s390/vfio-ccw.rst
> @@ -180,6 +180,13 @@ The process of how these work together.
> add it to an iommu_group and a vfio_group. Then we could pass through
> the mdev to a guest.
>
> +
> +VFIO-CCW Regions
> +----------------
> +
> +The vfio-ccw driver exposes MMIO regions to accept requests from and return
> +results to userspace.
> +
> vfio-ccw I/O region
> -------------------
>
> @@ -205,6 +212,25 @@ irb_area stores the I/O result.
>
> ret_code stores a return code for each access of the region.
>
> +This region is always available.
> +
> +vfio-ccw cmd region
> +-------------------
> +
> +The vfio-ccw cmd region is used to accept asynchronous instructions
> +from userspace.
> +
> +#define VFIO_CCW_ASYNC_CMD_HSCH (1 << 0)
> +#define VFIO_CCW_ASYNC_CMD_CSCH (1 << 1)
> +struct ccw_cmd_region {
> + __u32 command;
> + __u32 ret_code;
> +} __packed;
> +
> +This region is exposed via region type VFIO_REGION_SUBTYPE_CCW_ASYNC_CMD.
> +
> +CLEAR SUBCHANNEL and HALT SUBCHANNEL currently uses this region.

"Currently, CLEAR SUBCHANNEL and HALT SUBCHANNEL use this region". ?

> +
> vfio-ccw operation details
> --------------------------
>
> @@ -306,9 +332,8 @@ Together with the corresponding work in QEMU, we can bring the passed
> through DASD/ECKD device online in a guest now and use it as a block
> device.
>
> -While the current code allows the guest to start channel programs via
> -START SUBCHANNEL, support for HALT SUBCHANNEL or CLEAR SUBCHANNEL is
> -not yet implemented.
> +The current code allows the guest to start channel programs via
> +START SUBCHANNEL, and supports HALT SUBCHANNEL or CLEAR SUBCHANNEL.

"The current code allows the guest to start channel programs via START
SUBCHANNEL, and to issue HALT SUBCHANNEL and CLEAR SUBCHANNEL." ?

>
> vfio-ccw supports classic (command mode) channel I/O only. Transport
> mode (HPF) is not supported.