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Message-ID: <3bf9c7c4-4475-ad12-d146-a97b33d1e4ba@linux.ibm.com>
Date:   Wed, 2 Mar 2022 11:46:38 +0100
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Subject: Re: [PATCH v2 1/3] drivers/s390/char: Add Ultravisor io device
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To:     Janosch Frank <frankja@linux.ibm.com>, linux-s390@vger.kernel.org
Cc:     Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        David Hildenbrand <david@redhat.com>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>,
        Shuah Khan <shuah@kernel.org>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, linux-kselftest@vger.kernel.org
References: <20220223144830.44039-1-seiden@linux.ibm.com>
 <20220223144830.44039-2-seiden@linux.ibm.com>
 <7058948f-5514-4f8f-c974-f1ac624d67c3@linux.ibm.com>
From:   Steffen Eiden <seiden@linux.ibm.com>
Organization: IBM
In-Reply-To: <7058948f-5514-4f8f-c974-f1ac624d67c3@linux.ibm.com>
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On 3/2/22 11:34, Janosch Frank wrote:
> On 2/23/22 15:48, 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 is now able to call the Query Ultravisor Information
>> Ultravisor Command through the uvdevice.
>>
>> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
>> ---
[...]
>> +
>> +config S390_UV_UAPI
>> +    def_tristate y
>> +    prompt "Ultravisor userspace API"
>> +    depends on PROTECTED_VIRTUALIZATION_GUEST
> 
> Please drop the dependency.
> We want this to be available to both guest and host as QUI is available 
> in both environments and more calls like this could follow.
> 
> We could put an option around the attestation but the savings are not 
> worth the effort.

Makes sense. I will drop the dependency in v3.

Steffen