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 73E43C4167B for ; Fri, 3 Nov 2023 10:35:41 +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 3142760D3E for ; Fri, 3 Nov 2023 10:35:36 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 50693986D4B for ; Fri, 3 Nov 2023 10:35:35 +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 D5040986C7F; Fri, 3 Nov 2023 10:35:34 +0000 (UTC) Mailing-List: contact virtio-comment-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 C48D4986C31 for ; Fri, 3 Nov 2023 10:34:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10882"; a="373962298" X-IronPort-AV: E=Sophos;i="6.03,273,1694761200"; d="scan'208";a="373962298" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10882"; a="738043232" X-IronPort-AV: E=Sophos;i="6.03,273,1694761200"; d="scan'208";a="738043232" From: Zhu Lingshan To: jasowang@redhat.com, mst@redhat.com, eperezma@redhat.com, cohuck@redhat.com, stefanha@redhat.com Cc: virtio-comment@lists.oasis-open.org, parav@nvidia.com, Zhu Lingshan Date: Fri, 3 Nov 2023 18:34:33 +0800 Message-Id: <20231103103437.72784-3-lingshan.zhu@intel.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20231103103437.72784-1-lingshan.zhu@intel.com> References: <20231103103437.72784-1-lingshan.zhu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [virtio-comment] [PATCH V2 2/6] virtio: introduce SUSPEND bit in device status This patch introduces a new status bit in the device status: SUSPEND. This SUSPEND bit can be used by the driver to suspend a device, in order to stabilize the device states and virtqueue states. Its main use case is live migration. Signed-off-by: Zhu Lingshan Signed-off-by: Jason Wang Signed-off-by: Eugenio Pérez --- content.tex | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) diff --git a/content.tex b/content.tex index 76813b5..bcc9d4b 100644 --- a/content.tex +++ b/content.tex @@ -49,6 +49,10 @@ \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 +77,10 @@ \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 +90,26 @@ \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 descritors 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 Record Virtqueue State of each enabled virtqueue, see section \ref{sec:Virtqueues / Virtqueue State} +\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 +127,10 @@ \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 42] Feature bits reserved for extensions to the queue and +\item[24 to 43] Feature bits reserved for extensions to the queue and feature negotiation mechanisms -\item[43 to 49, and 128 and above] Feature bits reserved for future extensions. +\item[44 to 49, and 128 and above] Feature bits reserved for future extensions. \end{description} \begin{note} @@ -875,6 +903,10 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved Feature Bits} \item[VIRTIO_F_QUEUE_STATE(42)] This feature indicates that the device allows the driver to access its internal virtqueue state. + \item[VIRTIO_F_SUSPEND(43)] 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 This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. 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