Re: [RFC PATCH v1 06/10] KVM: s390: Add vm IOCTL for key checked guest absolute memory access

[Janis Schoetterl-Glausch]

On 1/19/22 13:53, Thomas Huth wrote:
> On 19/01/2022 13.46, Christian Borntraeger wrote:
>>
>>
>> Am 19.01.22 um 12:52 schrieb Thomas Huth:
>>> On 18/01/2022 10.52, Janis Schoetterl-Glausch wrote:
>>>> Channel I/O honors storage keys and is performed on absolute memory.
>>>> For I/O emulation user space therefore needs to be able to do key
>>>> checked accesses.
>>>
>>> Can't we do the checking in userspace? We already have functions for handling the storage keys there (see hw/s390x/s390-skeys-kvm.c), so why can't we do the checking in QEMU?
>>
>> That would separate the key check from the memory operation. Potentially for a long time.
>> Wenn we piggy back on access_guest_abs_with_key we use mvcos in the host and thus do the key check in lockstep with the keycheck which is the preferrable solution.
> 
> Ok, makes sense - Janis, could you please add this rationale to the patch description?

Will do.
> 
>  Thomas
>