linux-kernel - Re: [PATCH v4 1/2] drivers/s390/char: Add Ultravisor io device

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Message-ID: <78acfe88-97e3-92f9-29ef-736530179758@linux.ibm.com>
Date:   Tue, 17 May 2022 10:42:18 +0200
From:   Steffen Eiden <seiden@...ux.ibm.com>
To:     Janosch Frank <frankja@...ux.ibm.com>, Greg KH <greg@...ah.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Shuah Khan <shuah@...nel.org>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Nico Boehr <nrb@...ux.ibm.com>, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v4 1/2] drivers/s390/char: Add Ultravisor io device



On 5/17/22 10:38, Janosch Frank wrote:
> On 5/10/22 16:47, 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>
> 
> I'd like to pick this if I'm allowed to fix the two white space problems 
> below.
I am fine with that.

Thank you.

> 
>> ---
>>   MAINTAINERS                           |   2 +
>>   arch/s390/include/asm/uv.h            |  23 ++-
>>   arch/s390/include/uapi/asm/uvdevice.h |  51 +++++
>>   drivers/s390/char/Kconfig             |  10 +
>>   drivers/s390/char/Makefile            |   1 +
>>   drivers/s390/char/uvdevice.c          | 264 ++++++++++++++++++++++++++
>>   6 files changed, 350 insertions(+), 1 deletion(-)
>>   create mode 100644 arch/s390/include/uapi/asm/uvdevice.h
>>   create mode 100644 drivers/s390/char/uvdevice.c
>>
> 
>> +#endif  /* __S390_ASM_UVDEVICE_H */
> 
> There are two spaces between the "endif" and the "/"
> 
>> diff --git a/drivers/s390/char/Kconfig b/drivers/s390/char/Kconfig
>> index 6cc4b19acf85..e9b9902abbaf 100644
>> --- a/drivers/s390/char/Kconfig
>> +++ b/drivers/s390/char/Kconfig
>> @@ -100,6 +100,16 @@ config SCLP_OFB
>>         This option enables the Open-for-Business interface to the s390
>>         Service Element.
> [...]
>> + * uvio_attestation() does a  Retrieve Attestation Measurement 
>> Ultravisor Call.
> 
> Double space
> 
>> + * It verifies that the given userspace addresses are valid and 
>> request sizes
>> + * are sane. Every other check is made by the Ultravisor (UV) and 
>> won't result
>> + * in a negative return value. It copies the input to kernelspace, 
>> builds the
>> + * request, sends the UV-call, and copies the result to userspace.
>> + *
>