[PATCH v10 25/26] KVM: s390: CPU model support for AP virtualization

Tony Krowiak
2018-09-12T19:43:15Z

From: Tony Krowiak <akrowiak@linux.ibm.com>

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.

If this facility is not set for the KVM guest, then only
APQNs with an APQI less than 16 will be used by a Linux
guest regardless of the matrix configuration for the virtual
machine. This is a limitation of the Linux AP bus.

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.

If this facility is not set for the KVM guest, then no
AP devices will be available to the guest regardless of
the guest's matrix configuration for the virtual
machine. This is a limitation of the Linux AP bus.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Tested-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/kvm/kvm-s390.c | 5 +++++
arch/s390/tools/gen_facilities.c | 2 ++
2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 286c2e0..f0b8e2a 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -371,6 +371,11 @@ static void kvm_s390_cpu_feat_init(void)

if (MACHINE_HAS_ESOP)
allow_cpu_feat(KVM_S390_VM_CPU_FEAT_ESOP);
+
+ /* Check if AP instructions installed on host */
+ if (ap_instructions_available())
+ allow_cpu_feat(KVM_S390_VM_CPU_FEAT_AP);
+
/*
* We need SIE support, ESOP (PROT_READ protection for gmap_shadow),
* 64bit SCAO (SCA passthrough) and IDTE (for gmap_shadow unshadowing).
diff --git a/arch/s390/tools/gen_facilities.c b/arch/s390/tools/gen_facilities.c
index 0c85aed..fd788e0 100644
--- a/arch/s390/tools/gen_facilities.c
+++ b/arch/s390/tools/gen_facilities.c
@@ -106,6 +106,8 @@ struct facility_def {

.name = "FACILITIES_KVM_CPUMODEL",
.bits = (int[]){
+ 12, /* AP Query Configuration Information */
+ 15, /* AP Facilities Test */
156, /* etoken facility */
-1 /* END */
}
--
1.7.1