From: Janosch Frank <frankja@linux.ibm.com>
Date: Tue, 17 May 2022 16:36:29 +0000
Subject: Documentation/virt/kvm/api.rst: Explain rc/rrc delivery
Git-commit: b0f46280d3fcd59a65cfae9742fa5172362af893
Patch-mainline: v6.0-rc1
References: jsc#PED-622

Let's explain in which situations the rc/rrc will set in struct
kvm_pv_cmd so it's clear that the struct members should be set to
0. rc/rrc are independent of the IOCTL return code.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20220517163629.3443-12-frankja@linux.ibm.com
Message-Id: <20220517163629.3443-12-frankja@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 Documentation/virt/kvm/api.rst |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4846,6 +4846,14 @@ into ESA mode. This reset is a superset
 	__u32 reserved[3];
   };
 
+**Ultravisor return codes**
+The Ultravisor return (reason) codes are provided by the kernel if a
+Ultravisor call has been executed to achieve the results expected by
+the command. Therefore they are independent of the IOCTL return
+code. If KVM changes `rc`, its value will always be greater than 0
+hence setting it to 0 before issuing a PV command is advised to be
+able to detect a change of `rc`.
+
 **cmd values:**
 
 KVM_PV_ENABLE