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Tsirkin" To: Zhu Lingshan Cc: jasowang@redhat.com, eperezma@redhat.com, cohuck@redhat.com, stefanha@redhat.com, virtio-comment@lists.oasis-open.org, stevensd@chromium.org, virtio-dev@lists.oasis-open.org Message-ID: <20240218090935-mutt-send-email-mst@kernel.org> References: <20240218132306.83456-1-lingshan.zhu@intel.com> MIME-Version: 1.0 In-Reply-To: <20240218132306.83456-1-lingshan.zhu@intel.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [PATCH] virtio: introduce SUSPEND bit in device status On Sun, Feb 18, 2024 at 09:23:06PM +0800, Zhu Lingshan wrote: > 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 > Signed-off-by: Jason Wang > Signed-off-by: Eugenio Pérez Could we get some kind of dscription how this has taken into consideration the proposal from David Stevens? I find it really tiring when there are competing patches with authors ignoring each other's work and leaving it up to reviewers to figure out how do the patches compare. > --- > 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 --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org