From:   Claudio Imbrenda <imbrenda@linux.ibm.com>
To:     kvm@vger.kernel.org
Cc:     cohuck@redhat.com, borntraeger@de.ibm.com, frankja@linux.ibm.com,
        thuth@redhat.com, pasic@linux.ibm.com, david@redhat.com,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v6 15/17] KVM: s390: pv: api documentation for asynchronous destroy
Date:   Fri,  3 Dec 2021 17:58:12 +0100
Message-Id: <20211203165814.73016-16-imbrenda@linux.ibm.com>
In-Reply-To: <20211203165814.73016-1-imbrenda@linux.ibm.com>
References: <20211203165814.73016-1-imbrenda@linux.ibm.com>
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Add documentation for the new commands added to the KVM_S390_PV_COMMAND
ioctl.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
---
 Documentation/virt/kvm/api.rst | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index aeeb071c7688..f4d981cd58fa 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4975,11 +4975,13 @@ 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.
+  again. All registered VCPUs are converted back to non-protected
+  ones. If a previous VM had been prepared for asynchonous teardown
+  with KVM_PV_ASYNC_DISABLE_PREPARE and not actually torn down with
+  KVM_PV_ASYNC_DISABLE, it will be torn down in this call together with
+  the current VM.
 
 KVM_PV_VM_SET_SEC_PARMS
   Pass the image header from VM memory to the Ultravisor in
@@ -4992,6 +4994,19 @@ KVM_PV_VM_VERIFY
   Verify the integrity of the unpacked image. Only if this succeeds,
   KVM is allowed to start protected VCPUs.
 
+KVM_PV_ASYNC_DISABLE_PREPARE
+  Prepare the current protected VM for asynchronous teardown. The current
+  VM will then continue immediately as non-protected. If a protected VM had
+  already been set aside without starting the teardown process, this call
+  will fail. In this case the userspace process should issue a normal
+  KVM_PV_DISABLE.
+
+KVM_PV_ASYNC_DISABLE
+  Tear down the protected VM previously set aside for asynchronous teardown.
+  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.
+
 4.126 KVM_X86_SET_MSR_FILTER
 ----------------------------
 
-- 
2.31.1