On Wed, 14 Mar 2018 14:25:43 -0400 Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> wrote: > Introduces a new CPU model feature and two CPU model > facilities to support AP virtualization for KVM guests. > > CPU model feature: > > The KVM_S390_VM_CPU_FEAT_AP feature indicates that > AP instructions are available on the guest. This > feature will be enabled by the kernel only if the AP > instructions are installed on the linux host. This feature > must be specifically turned on for the KVM guest from > userspace to use the VFIO AP device driver for guest > access to AP devices. > > CPU model facilities: > > 1. AP Query Configuration Information (QCI) facility is installed. > > This is indicated by setting facilities bit 12 for > the guest. The kernel will not enable this facility > for the guest if it is not set on the host. This facility > must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP > feature is not installed. > > 2. AP Facilities Test facility (APFT) is installed. > > This is indicated by setting facilities bit 15 for > the guest. The kernel will not enable this facility for > the guest if it is not set on the host. This facility > must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP > feature is not installed. > > Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> > Reviewed-by: Halil Pasic <pasic@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> > --- > arch/s390/include/asm/kvm_host.h | 1 + > arch/s390/include/uapi/asm/kvm.h | 1 + > arch/s390/kvm/kvm-s390.c | 4 ++++ > arch/s390/tools/gen_facilities.c | 2 ++ > 4 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index c47731d..a60c45b 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -350,6 +350,10 @@ static void kvm_s390_cpu_feat_init(void) > > if (MACHINE_HAS_ESOP) > allow_cpu_feat(KVM_S390_VM_CPU_FEAT_ESOP); > + > + if (ap_instructions_installed()) /* AP instructions installed on host */ > + allow_cpu_feat(KVM_S390_VM_CPU_FEAT_AP); That's another dependency of the base kvm-s390 module on zcrypt, which I don't like at all. There are two possibilities here: - Exposing the features makes sense even if no zcrypt driver is active in the host. Then, ap_instructions_installed() needs to be moved into always-built code (see my comments for the interface in patch 1). - Exposing the features makes sense only if we actually want to make vfio-ap available. Then we should provide the proper check in the vfio-ap parts (which depends on zcrypt) and stub it out if vfio-ap is not configured. > + > /* > * We need SIE support, ESOP (PROT_READ protection for gmap_shadow), > * 64bit SCAO (SCA passthrough) and IDTE (for gmap_shadow unshadowing).
