Introduction to Protected VMs. Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx> --- Documentation/virtual/kvm/s390-pv.txt | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 Documentation/virtual/kvm/s390-pv.txt diff --git a/Documentation/virtual/kvm/s390-pv.txt b/Documentation/virtual/kvm/s390-pv.txt new file mode 100644 index 000000000000..86ed95f36759 --- /dev/null +++ b/Documentation/virtual/kvm/s390-pv.txt @@ -0,0 +1,23 @@ +Ultravisor and Protected VMs +=========================== + +Summary: + +Protected VMs (PVM) are KVM VMs, where KVM can't access the VM's state +like guest memory and guest registers anymore. Instead the PVMs are +mostly managed by a new entity called Ultravisor (UV), which provides +an API, so KVM and the PVM can request management actions. + +Each guest starts in the non-protected mode and then transitions into +protected mode. On transition KVM registers the guest and its VCPUs +with the Ultravisor and prepares everything for running it. + +The Ultravisor will secure and decrypt the guest's boot memory +(i.e. kernel/initrd). It will safeguard state changes like VCPU +starts/stops and injected interrupts while the guest is running. + +As access to the guest's state, like the SIE state description is +normally needed to be able to run a VM, some changes have been made in +SIE behavior and fields have different meaning for a PVM. SIE exits +are minimized as much as possible to improve speed and reduce exposed +guest state. -- 2.20.1
