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

Thomas

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