From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 588A2C48BC3 for ; Tue, 20 Feb 2024 03:44:53 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 949D222363 for ; Tue, 20 Feb 2024 03:44:52 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 719259864BB for ; Tue, 20 Feb 2024 03:44:52 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id 56FBE98648B; Tue, 20 Feb 2024 03:44:52 +0000 (UTC) Mailing-List: contact virtio-dev-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 41EA59864A3 for ; Tue, 20 Feb 2024 03:44:52 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10989"; a="2633501" X-IronPort-AV: E=Sophos;i="6.06,171,1705392000"; d="scan'208";a="2633501" X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,171,1705392000"; d="scan'208";a="4897426" Message-ID: Date: Tue, 20 Feb 2024 11:44:44 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: "Michael S. Tsirkin" 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 References: <20240218132306.83456-1-lingshan.zhu@intel.com> <20240218090935-mutt-send-email-mst@kernel.org> Content-Language: en-US From: "Zhu, Lingshan" In-Reply-To: <20240218090935-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [PATCH] virtio: introduce SUSPEND bit in device status On 2/18/2024 10:11 PM, Michael S. Tsirkin wrote: > 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? sure thing, we can work with David together for a solution. > > 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