Messages in this thread | | | Date | Wed, 19 Jan 2022 13:46:43 +0100 | Subject | Re: [RFC PATCH v1 06/10] KVM: s390: Add vm IOCTL for key checked guest absolute memory access | From | Christian Borntraeger <> |
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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.
I would also like to avoid reading guest storage keys via the ioctl that was done for migration in the I/O path just to do a single key check. This has peformance concerns.
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