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

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Message-ID: <859962fd-cb55-42ea-78f0-75677953bb58@linux.ibm.com>
Date:   Thu, 17 Mar 2022 12:23:16 +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 12:07, Steffen Eiden wrote:
> 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/ 
> 
I forgot to point out that the Attestation userspace tool will be 
open-source and included in the s390-tool package.
I can send you the current state of that tool in private if you want.

> 
> 
>> thanks,
>>
>> greg k-h
>>
> 
> steffen

steffen