Re: [PATCH RFC 2/2] KVM: s390: introduce and use KVM_REQ_VSIE_RESTART

[Cornelia Huck]

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?

> 
> 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>