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

Steffen Eiden
2022-10-04T13:44:17Z

On 9/30/22 16:01, Claudio Imbrenda wrote:
> 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>LGTM.

Reviewed-by: Steffen Eiden <seiden@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
> ----------------------------