[PATCH v14 2/6] KVM: s390: pv: api documentation for asynchronous destroy

Claudio Imbrenda
2022-09-30T14:02:07Z

Add documentation for the new commands added to the KVM_S390_PV_COMMAND
ioctl.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
---
Documentation/virt/kvm/api.rst | 37 ++++++++++++++++++++++++++++++----
1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index abd7c32126ce..5775e5fbfd18 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -5161,10 +5161,13 @@ KVM_PV_ENABLE
===== =============================

KVM_PV_DISABLE
- Deregister the VM from the Ultravisor and reclaim the memory that
- had been donated to the Ultravisor, making it usable by the kernel
- again. All registered VCPUs are converted back to non-protected
- ones.
+ Deregister the VM from the Ultravisor and reclaim the memory that had
+ been donated to the Ultravisor, making it usable by the kernel again.
+ All registered VCPUs are converted back to non-protected ones. If a
+ previous protected VM had been prepared for asynchonous teardown with
+ KVM_PV_ASYNC_CLEANUP_PREPARE and not subsequently torn down with
+ KVM_PV_ASYNC_CLEANUP_PERFORM, it will be torn down in this call
+ together with the current protected VM.

KVM_PV_VM_SET_SEC_PARMS
Pass the image header from VM memory to the Ultravisor in
@@ -5287,6 +5290,32 @@ KVM_PV_DUMP
authentication tag all of which are needed to decrypt the dump at a
later time.

+KVM_PV_ASYNC_CLEANUP_PREPARE
+ Prepare the current protected VM for asynchronous teardown. Most
+ resources used by the current protected VM will be set aside for a
+ subsequent asynchronous teardown. The current protected VM will then
+ resume execution immediately as non-protected. There can be at most
+ one protected VM prepared for asynchronous teardown at any time. If
+ a protected VM had already been prepared for teardown without
+ subsequently calling KVM_PV_ASYNC_CLEANUP_PERFORM, this call will
+ fail. In that case, the userspace process should issue a normal
+ KVM_PV_DISABLE. The resources set aside with this call will need to
+ be cleaned up with a subsequent call to KVM_PV_ASYNC_CLEANUP_PERFORM
+ or KVM_PV_DISABLE, otherwise they will be cleaned up when KVM
+ terminates. KVM_PV_ASYNC_CLEANUP_PREPARE can be called again as soon
+ as cleanup starts, i.e. before KVM_PV_ASYNC_CLEANUP_PERFORM finishes.
+
+KVM_PV_ASYNC_CLEANUP_PERFORM
+ Tear down the protected VM previously prepared for teardown with
+ KVM_PV_ASYNC_CLEANUP_PREPARE. The resources that had been set aside
+ will be freed during the execution of this command. This PV command
+ should ideally be issued by userspace from a separate thread. If a
+ fatal signal is received (or the process terminates naturally), the
+ command will terminate immediately without completing, and the normal
+ KVM shutdown procedure will take care of cleaning up all remaining
+ protected VMs, including the ones whose teardown was interrupted by
+ process termination.
+

4.126 KVM_X86_SET_MSR_FILTER
----------------------------
--
2.37.3