[PATCH] ccw: clarify device reset

[Cornelia Huck <cohuck@redhat.com>]

Unlike other transports, a reset triggered by the driver is actually
complete once the command has been completed. Make this behaviour
and the requirements more explicit.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---

We have discussed this before while talking about reset behaviour,
but I don't remember sending an actual patch.

If this looks good, I'll open an issue.

---
 conformance.tex |  2 ++
 content.tex     | 22 +++++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/conformance.tex b/conformance.tex
index c52f1a40be2d..24e862ad217a 100644
--- a/conformance.tex
+++ b/conformance.tex
@@ -122,6 +122,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
 \item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information}
 \item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host->Guest Notification / Notification via Adapter I/O Interrupts}
 \item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Guest->Host Notification}
+\item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Resetting Devices}
 \end{itemize}
 
 \conformance{\subsection}{Network Driver Conformance}\label{sec:Conformance / Driver Conformance / Network Driver Conformance}
@@ -372,6 +373,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
 \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Setting Up Two-Stage Queue Indicators}
 \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host->Guest Notification / Notification via Adapter I/O Interrupts}
 \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Guest->Host Notification}
+\item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Resetting Devices}
 \end{itemize}
 
 \conformance{\subsection}{Network Device Conformance}\label{sec:Conformance / Device Conformance / Network Device Conformance}
diff --git a/content.tex b/content.tex
index 5e716721edb3..0410f46f6a78 100644
--- a/content.tex
+++ b/content.tex
@@ -2775,8 +2775,28 @@ \subsubsection{Guest->Host Notification}\label{sec:Virtio Transport Options / Vi
 \subsubsection{Resetting Devices}\label{sec:Virtio Transport Options / Virtio over channel I/O / Device Operation / Resetting Devices}
 
 In order to reset a device, a driver sends the
-CCW_CMD_VDEV_RESET command.
+CCW_CMD_VDEV_RESET command. This command does not carry any payload.
 
+The device signals completion of the reset operation by making the subchannel
+status pending to indicate successful completion of the channel command.
+Notably, the command not only triggers the reset operation, but the reset
+operation is already completed when the operation concludes successfully.
+
+\devicenormative{\paragraph}{Resetting Devices}{Virtio Transport Options / Virtio over channel I/O / Device Operation / Resetting Devices}
+
+Before making the subchannel status pending to indicate successful completion
+of the reset command, the device MUST reinitialize \field{device status} to
+zero.
+
+The device MUST NOT send notifications or interact with the queues after
+it signaled successful completion of the reset command.
+
+\drivernormative{\paragraph}{Resetting Devices}{Virtio Transport Options / Virtio over channel I/O / Device Operation / Resetting Devices}
+
+The driver MAY consider the reset operation to be complete already after
+successful completion of the channel command, although it MAY also verify
+reset completion by reading \field{device status} via CCW_CMD_READ_STATUS
+afterwards.
 
 \chapter{Device Types}\label{sec:Device Types}
 
-- 
2.31.1