From: Zhu Lingshan <lingshan.zhu@intel.com>
To: jasowang@redhat.com, mst@redhat.com, eperezma@redhat.com,
cohuck@redhat.com, stefanha@redhat.com
Cc: virtio-comment@lists.oasis-open.org, stevensd@chromium.org,
virtio-dev@lists.oasis-open.org,
Zhu Lingshan <lingshan.zhu@intel.com>
Subject: [virtio-comment] [PATCH] virtio: introduce SUSPEND bit in device status
Date: Sun, 18 Feb 2024 21:23:06 +0800 [thread overview]
Message-ID: <20240218132306.83456-1-lingshan.zhu@intel.com> (raw)
This commit allows the driver to suspend the device by
introducing a new status bit SUSPEND in device_status.
This commit also introduce a new feature bit VIRTIO_F_SUSPEND
which indicating whether the device support SUSPEND.
This SUSPEND bit is transport-independent.
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
content.tex | 34 ++++++++++++++++++++++++++++++++--
1 file changed, 32 insertions(+), 2 deletions(-)
diff --git a/content.tex b/content.tex
index 0a62dce..3d656b5 100644
--- a/content.tex
+++ b/content.tex
@@ -49,6 +49,9 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev
\item[DEVICE_NEEDS_RESET (64)] Indicates that the device has experienced
an error from which it can't recover.
+
+\item[SUSPEND (16)] When VIRTIO_F_SUSPEND is negotiated, indicates that the
+ device has been suspended by the driver.
\end{description}
The \field{device status} field starts out as 0, and is reinitialized to 0 by
@@ -73,6 +76,10 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev
recover by issuing a reset.
\end{note}
+The driver SHOULD NOT set SUSPEND if FEATURES_OK is not set.
+
+When setting SUSPEND, the driver MUST re-read \field{device status} to ensure the SUSPEND bit is set.
+
\devicenormative{\subsection}{Device Status Field}{Basic Facilities of a Virtio Device / Device Status Field}
The device MUST NOT consume buffers or send any used buffer
@@ -82,6 +89,25 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev
that a reset is needed. If DRIVER_OK is set, after it sets DEVICE_NEEDS_RESET, the device
MUST send a device configuration change notification to the driver.
+The device MUST ignore SUSPEND if FEATURES_OK is not set.
+
+The device MUST ignore SUSPEND if VIRTIO_F_SUSPEND is not negotiated.
+
+The device SHOULD allow settings to \field{device status} even when SUSPEND is set.
+
+If VIRTIO_F_SUSPEND is negotiated and SUSPEND is set, the device SHOULD clear SUSPEND
+and resumes operation upon DRIVER_OK.
+
+If VIRTIO_F_SUSPEND is negotiated, when the driver sets SUSPEND,
+the device SHOULD perform the following actions before presenting SUSPEND bit in the \field{device status}:
+
+\begin{itemize}
+\item Stop consuming buffers of any virtqueues and mark all finished descriptors as used.
+\item Wait until all descriptors that being processed to finish and mark them as used.
+\item Flush all used buffer and send used buffer notifications to the driver.
+\item Pause its operation except \field{device status} and preserve configurations in its Device Configuration Space, see \ref{sec:Basic Facilities of a Virtio Device / Device Configuration Space}
+\end{itemize}
+
\section{Feature Bits}\label{sec:Basic Facilities of a Virtio Device / Feature Bits}
Each virtio device offers all the features it understands. During
@@ -99,10 +125,10 @@ \section{Feature Bits}\label{sec:Basic Facilities of a Virtio Device / Feature B
\begin{description}
\item[0 to 23, and 50 to 127] Feature bits for the specific device type
-\item[24 to 41] Feature bits reserved for extensions to the queue and
+\item[24 to 42] Feature bits reserved for extensions to the queue and
feature negotiation mechanisms
-\item[42 to 49, and 128 and above] Feature bits reserved for future extensions.
+\item[43 to 49, and 128 and above] Feature bits reserved for future extensions.
\end{description}
\begin{note}
@@ -872,6 +898,10 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved Feature Bits}
\ref{devicenormative:Basic Facilities of a Virtio Device / Feature Bits} for
handling features reserved for future use.
+ \item[VIRTIO_F_SUSPEND(42)] This feature indicates that the driver can
+ SUSPEND the device.
+ See \ref{sec:Basic Facilities of a Virtio Device / Device Status Field}.
+
\end{description}
\drivernormative{\section}{Reserved Feature Bits}{Reserved Feature Bits}
--
2.35.3
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next reply other threads:[~2024-02-18 13:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-18 13:23 Zhu Lingshan [this message]
2024-02-18 14:11 ` [virtio-comment] Re: [PATCH] virtio: introduce SUSPEND bit in device status Michael S. Tsirkin
2024-02-19 6:46 ` David Stevens
2024-02-20 4:06 ` Zhu, Lingshan
2024-02-20 5:09 ` David Stevens
2024-02-20 7:48 ` Michael S. Tsirkin
2024-02-23 7:46 ` Zhu, Lingshan
2024-02-23 7:44 ` Zhu, Lingshan
2024-02-25 8:52 ` Michael S. Tsirkin
2024-02-26 1:36 ` Zhu, Lingshan
2024-02-26 2:43 ` David Stevens
2024-02-20 3:44 ` Zhu, Lingshan
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