From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-comment-return-1569-cohuck=redhat.com@lists.oasis-open.org Sender: 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 ED6909865AB for ; Fri, 18 Dec 2020 04:23:24 +0000 (UTC) From: Jason Wang Date: Fri, 18 Dec 2020 12:23:02 +0800 Message-Id: <20201218042302.8884-1-jasowang@redhat.com> MIME-Version: 1.0 Subject: [virtio-comment] [PATCH RFC] virtio: introduce VIRTIO_F_DEVICE_STOP Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable To: stefanha@redhat.com, virtio-comment@lists.oasis-open.org, mst@redhat.com Cc: eperezma@redhat.com, sgarzare@redhat.com, Jason Wang List-ID: This patch introduces a new status bit DEVICE_STOPPED. This will be used by the driver to stop and resume a device. The main user will be live migration support for virtio device. Signed-off-by: Jason Wang --- content.tex | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/content.tex b/content.tex index 61eab41..4392b60 100644 --- a/content.tex +++ b/content.tex @@ -47,6 +47,9 @@ \section{\field{Device Status} Field}\label{sec:Basic Fac= ilities of a Virtio Dev \item[DRIVER_OK (4)] Indicates that the driver is set up and ready to drive the device. =20 +\item[DEVICE_STOPPED (32)] When VIRTIO_F_DEVICE_STOPPED is negotiated, + indicates that the device has been stopped by the driver. + \item[DEVICE_NEEDS_RESET (64)] Indicates that the device has experienced an error from which it can't recover. \end{description} @@ -58,8 +61,9 @@ \section{\field{Device Status} Field}\label{sec:Basic Fac= ilities of a Virtio Dev \ref{sec:General Initialization And Device Operation / Device Initialization}. The driver MUST NOT clear a -\field{device status} bit. If the driver sets the FAILED bit, -the driver MUST later reset the device before attempting to re-initialize. +\field{device status} bit other than DEVICE_STOPPED. If the +driver sets the FAILED bit, the driver MUST later reset the device +before attempting to re-initialize. =20 The driver SHOULD NOT rely on completion of operations of a device if DEVICE_NEEDS_RESET is set. @@ -70,12 +74,28 @@ \section{\field{Device Status} Field}\label{sec:Basic F= acilities of a Virtio Dev recover by issuing a reset. \end{note} =20 +The driver MUST NOT set or clear DEVICE_STOPPED when DRIVER_OK is not +set. In order to stop the device, the driver MUST set DEVICE_STOPPED +first and re-read status to check whether DEVICE_STOPPED is set by the +device. In order to resume the device, the driver MUST clear +DEVICE_STOPPED first and read status to ensure whether DEVICE_STOPPED +is cleared by the device. + \devicenormative{\subsection}{Device Status Field}{Basic Facilities of a V= irtio Device / Device Status Field} The device MUST initialize \field{device status} to 0 upon reset. =20 The device MUST NOT consume buffers or send any used buffer notifications to the driver before DRIVER_OK. =20 +The device MUST ignore DEVICE_STOPPED when DRIVER_OK is not set. + +When driver is trying to set DEVICE_STOPPED, the device MUST not +process new avail requests and MUST complete all requests that is +currently processing before setting DEVICE_STOPPED. + +The device MUST keep the config space unchanged when DEVICE_STOPPED is +set. + \label{sec:Basic Facilities of a Virtio Device / Device Status Field / DEV= ICENEEDSRESET}The device SHOULD set DEVICE_NEEDS_RESET when it enters an er= ror state that a reset is needed. If DRIVER_OK is set, after it sets DEVICE_NEEDS_R= ESET, the device MUST send a device configuration change notification to the driver. @@ -6553,6 +6573,8 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved Fe= ature Bits} \item[VIRTIO_F_NOTIFICATION_DATA(38)] This feature indicates that the driver passes extra data (besides identifying the virtqueue) in its device notifications. + \item[VIRTIO_F_DEVICE_STOP(39)] This feature indicates that the + driver can stop and resume the device. See \ref{sec:Virtqueues / Driver notifications}~\nameref{sec:Virtqueues = / Driver notifications}. \end{description} =20 --=20 2.25.1 This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lis= ts Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/