Re: [PATCH v3 1/4] drivers/s390/char: Add Ultravisor io device'

[Greg KH]

On Thu, Mar 17, 2022 at 09:47:06AM +0000, Steffen Eiden wrote:
> This patch adds a new miscdevice to expose some Ultravisor functions
> to userspace. Userspace can send IOCTLs to the uvdevice that will then
> emit a corresponding Ultravisor Call and hands the result over to
> userspace. The uvdevice is available if the Ultravisor Call facility is
> present.
> Userspace can call the Retrieve Attestation Measurement
> Ultravisor Call using IOCTLs on the uvdevice.
> 
> The uvdevice will do some sanity checks first.
> Then, copy the request data to kernel space, build the UVCB,
> perform the UV call, and copy the result back to userspace.
> 
> Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
> Reviewed-by: Janosch Frank <frankja@xxxxxxxxxxxxx>

Do you have a pointer to the userspace code that interacts with this
kernel driver?  That would be good to have to verify that the api here
is sane.

thanks,

greg k-h