summaryrefslogtreecommitdiff
path: root/Documentation/virt/kvm/api.rst
diff options
context:
space:
mode:
authorPierre Morel <pmorel@linux.ibm.com>2022-07-14 22:43:34 +0300
committerJanosch Frank <frankja@linux.ibm.com>2022-07-20 11:57:37 +0300
commitf5ecfee94493475783074e86ded10a0499d779fc (patch)
tree996d75fb3e60b1c3230ee472148703f87a938605 /Documentation/virt/kvm/api.rst
parent24fe0195bc19306b2769b43b3e22bd35bd6fb061 (diff)
downloadlinux-f5ecfee94493475783074e86ded10a0499d779fc.tar.xz
KVM: s390: resetting the Topology-Change-Report
During a subsystem reset the Topology-Change-Report is cleared. Let's give userland the possibility to clear the MTCR in the case of a subsystem reset. To migrate the MTCR, we give userland the possibility to query the MTCR state. We indicate KVM support for the CPU topology facility with a new KVM capability: KVM_CAP_S390_CPU_TOPOLOGY. Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> Reviewed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com> Reviewed-by: Janosch Frank <frankja@linux.ibm.com> Message-Id: <20220714194334.127812-1-pmorel@linux.ibm.com> Link: https://lore.kernel.org/all/20220714194334.127812-1-pmorel@linux.ibm.com/ [frankja@linux.ibm.com: Simple conflict resolution in Documentation/virt/kvm/api.rst] Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Diffstat (limited to 'Documentation/virt/kvm/api.rst')
-rw-r--r--Documentation/virt/kvm/api.rst25
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 5be5cc59869d..3c4551a2f6d0 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8269,6 +8269,31 @@ The capability has no effect if the nx_huge_pages module parameter is not set.
This capability may only be set before any vCPUs are created.
+8.39 KVM_CAP_S390_CPU_TOPOLOGY
+------------------------------
+
+:Capability: KVM_CAP_S390_CPU_TOPOLOGY
+:Architectures: s390
+:Type: vm
+
+This capability indicates that KVM will provide the S390 CPU Topology
+facility which consist of the interpretation of the PTF instruction for
+the function code 2 along with interception and forwarding of both the
+PTF instruction with function codes 0 or 1 and the STSI(15,1,x)
+instruction to the userland hypervisor.
+
+The stfle facility 11, CPU Topology facility, should not be indicated
+to the guest without this capability.
+
+When this capability is present, KVM provides a new attribute group
+on vm fd, KVM_S390_VM_CPU_TOPOLOGY.
+This new attribute allows to get, set or clear the Modified Change
+Topology Report (MTCR) bit of the SCA through the kvm_device_attr
+structure.
+
+When getting the Modified Change Topology Report value, the attr->addr
+must point to a byte where the value will be stored or retrieved from.
+
9. Known KVM API problems
=========================