Re: [PATCH RFC 1/2] KVM: s390: vsie: simulate VCPU SIE entry/exit

From: Cornelia Huck
Date: Wed Aug 08 2018 - 08:44:21 EST

On Tue, 7 Aug 2018 14:51:30 +0200
David Hildenbrand <david@xxxxxxxxxx> wrote:

> VCPU requests and VCPU blocking right now don't take care of the vSIE
> (as it was not necessary until now). But we want to have VCPU requests
> that will also be handled before running the vSIE again.
> So let's simulate a SIE entry when entering the vSIE loop and check
> for PROG_ flags. The existing infrastructure (e.g. exit_sie()) will then
> detect that the SIE (in form of the vSIE execution loop) is running and
> properly kick the vSIE CPU, resulting in it leaving the vSIE loop and
> therefore the vSIE interception handler, allowing it to handle VCPU
> requests.
> E.g. if we want to modify the crycb of the VCPU and make sure that any
> masks also get applied to the VSIE crycb shadow (which uses masks from the
> VCPU crycb), we will need a way to hinder the vSIE from running and make
> sure to process the updated crycb before reentering the vSIE again.
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> ---
> arch/s390/kvm/kvm-s390.c | 9 ++++++++-
> arch/s390/kvm/kvm-s390.h | 1 +
> arch/s390/kvm/vsie.c | 20 ++++++++++++++++++--
> 3 files changed, 27 insertions(+), 3 deletions(-)

Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>