On 08.08.2018 14:47, Cornelia Huck wrote: > On Tue, 7 Aug 2018 14:51:31 +0200 > David Hildenbrand <david@xxxxxxxxxx> wrote: > >> When we change the crycb (or execution controls), we also have to make sure >> that the vSIE shadow datastructures properly consider the changed >> values before rerunning the vSIE. We can achieve that by simply using a >> VCPU request now. > > Is this actually a concrete problem right now, or does this only become > a real concern with vfio-ap? The use case I implemented is not a real problem right now, at least not in practice. In QEMU, s390_crypto_reset() triggers this code, but it is only called when all VCPUs are stopped (== no one in vSIE). So this change is the right thing to do ("who knows what user space does"), but not critical (we're only dealing with wrapping masks right now). It is a problem once we allow to access adapters (vfio-ap). > >> >> This has to be a synchronous request (== handled before entering the >> (v)SIE again). >> >> The request will make sure that the vSIE handler is left, and that the >> request will be processed (NOP), therefore forcing a reload of all >> vSIE data (including rebuilding the crycb) when re-entering the vSIE >> interception handler the next time. >> >> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> >> --- >> arch/s390/include/asm/kvm_host.h | 1 + >> arch/s390/kvm/kvm-s390.c | 7 ++++++- >> 2 files changed, 7 insertions(+), 1 deletion(-) > > Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx> > -- Thanks, David / dhildenb -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html