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

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Message-ID: <6175e7fa-070e-8ab2-843a-8019d0dc0c83@linux.ibm.com>
Date:   Thu, 17 Mar 2022 12:07:58 +0100
From:   Steffen Eiden <seiden@...ux.ibm.com>
To:     Greg KH <greg@...ah.com>
Cc:     agordeev@...ux.ibm.com, borntraeger@...ux.ibm.com,
        david@...hat.com, frankja@...ux.ibm.com, gor@...ux.ibm.com,
        hca@...ux.ibm.com, imbrenda@...ux.ibm.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-s390@...r.kernel.org, nrb@...ux.ibm.com, shuah@...nel.org
Subject: Re: [PATCH v3 1/4] drivers/s390/char: Add Ultravisor io device

Hi greg,

On 3/17/22 10:59, Greg KH wrote:
> 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@...ux.ibm.com>
>> Reviewed-by: Janosch Frank <frankja@...ux.ibm.com>
> 
> 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.
> 
There is a userspace tool currently under development, however, not yet 
ready to be published.
Currently, I can only point to the Kselftest in this series and the 
kvm-unit-tests at 
https://lore.kernel.org/linux-s390/20220203091935.2716-1-seiden@linux.ibm.com/


> thanks,
> 
> greg k-h
> 

steffen