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 AEA5DEDE989 for ; Fri, 15 Sep 2023 02:46:58 +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 182292AC54 for ; Fri, 15 Sep 2023 02:46:58 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 0DDF6986669 for ; Fri, 15 Sep 2023 02:46:58 +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 00C70983C27; Fri, 15 Sep 2023 02:46:58 +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 DF03A986659; Fri, 15 Sep 2023 02:46:52 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10833"; a="381868860" X-IronPort-AV: E=Sophos;i="6.02,147,1688454000"; d="scan'208";a="381868860" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10833"; a="888047777" X-IronPort-AV: E=Sophos;i="6.02,147,1688454000"; d="scan'208";a="888047777" Message-ID: <5392f834-7755-b83d-a504-a6e720882129@intel.com> Date: Fri, 15 Sep 2023 10:46:36 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.15.1 Content-Language: en-US To: "Michael S. Tsirkin" Cc: jasowang@redhat.com, eperezma@redhat.com, cohuck@redhat.com, stefanha@redhat.com, virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org References: <20230906081637.32185-1-lingshan.zhu@intel.com> <20230906081637.32185-2-lingshan.zhu@intel.com> <20230914071439-mutt-send-email-mst@kernel.org> From: "Zhu, Lingshan" In-Reply-To: <20230914071439-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [virtio-comment] [PATCH 1/5] virtio: introduce vq state as basic facility On 9/14/2023 7:25 PM, Michael S. Tsirkin wrote: > On Wed, Sep 06, 2023 at 04:16:33PM +0800, Zhu Lingshan wrote: >> This patch adds new device facility to save and restore virtqueue >> state. The virtqueue state is split into two parts: >> >> - The available state: The state that is used for read the next >> available buffer. >> - The used state: The state that is used for make buffer used. >> >> This will simply the transport specific method implementation. E.g two >> le16 could be used instead of a single le32). For split virtqueue, we >> only need the available state since the used state is implemented in >> the virtqueue itself (the used index). > hmm no, simply because when ring is not running and when > buffers are processed in order, last avail == used. in the ideal case, yes. I will remove this since this may be ambiguous. > >> For packed virtqueue, we need >> both the available state and the used state. >> >> Those states are required to implement live migration support for >> virtio device. >> >> Signed-off-by: Zhu Lingshan >> Signed-off-by: Jason Wang >> Signed-off-by: Eugenio Pérez > > >> --- >> content.tex | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 65 insertions(+) >> >> diff --git a/content.tex b/content.tex >> index 0a62dce..0e492cd 100644 >> --- a/content.tex >> +++ b/content.tex >> @@ -502,6 +502,71 @@ \section{Exporting Objects}\label{sec:Basic Facilities of a Virtio Device / Expo >> types. It is RECOMMENDED that devices generate version 4 >> UUIDs as specified by \hyperref[intro:rfc4122]{[RFC4122]}. >> >> +\section{Virtqueue State}\label{sec:Virtqueues / Virtqueue State} >> + >> +When VIRTIO_F_QUEUE_STATE has been negotiated, the driver can set and >> +get the device internal virtqueue state through the following >> +fields. The implementation of the interfaces is transport specific. >> + >> +\subsection{\field{Available State} Field} >> + >> +The available state field is two bytes of virtqueue state that is used by >> +the device to read the next available buffer. >> + >> +When VIRTIO_RING_F_PACKED is not negotiated, it contains: >> + >> +\begin{lstlisting} >> +le16 last_avail_idx; >> +\end{lstlisting} >> + >> +The \field{last_avail_idx} field is the free-running available ring >> +index where the device will read the next available head of a >> +descriptor chain. > I dislike how this pokes at split-ring.txt externally. > Will make it harder to add new formats down the road. I can move these contents to split-ring.tex and packed-ring.tex respectively, however some contents have to be duplicated. Thanks > > > >> + >> +See also \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Available Ring}. >> >> +When VIRTIO_RING_F_PACKED is negotiated, it contains: >> + >> +\begin{lstlisting} >> +le16 { >> + last_avail_idx : 15; >> + last_avail_wrap_counter : 1; >> +}; >> +\end{lstlisting} >> + >> +The \field{last_avail_idx} field is the free-running location >> +where the device read the next descriptor from the virtqueue descriptor ring. >> + >> +The \field{last_avail_wrap_counter} field is the last driver ring wrap >> +counter that was observed by the device. >> + >> +See also \ref{sec:Packed Virtqueues / Driver and Device Ring Wrap Counters}. > >> +\subsection{\field{Used State} Field} >> + >> +The used state field is two bytes of virtqueue state that is used by >> +the device when marking a buffer used. >> + >> +When VIRTIO_RING_F_PACKED is negotiated, the used state contains: >> + >> +\begin{lstlisting} >> +le16 { >> + used_idx : 15; >> + used_wrap_counter : 1; >> +}; >> +\end{lstlisting} >> + >> +The \field{used_idx} field is the free-running location where the device write the next >> +used descriptor to the descriptor ring. >> + >> +The \field{used_wrap_counter} field is the wrap counter that is used >> +by the device. >> + >> +See also \ref{sec:Packed Virtqueues / Driver and Device Ring Wrap Counters}. >> + >> +When VIRTIO_RING_F_PACKED is not negotiated, the 16-bit value of \field{used_idx} >> +is always 0 >> + >> \input{admin.tex} >> >> \chapter{General Initialization And Device Operation}\label{sec:General Initialization And Device Operation} >> -- >> 2.35.3 >> >> >> 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-lists >> Committee: https://www.oasis-open.org/committees/virtio/ >> Join OASIS: https://www.oasis-open.org/join/ >> > > 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-lists > Committee: https://www.oasis-open.org/committees/virtio/ > Join OASIS: https://www.oasis-open.org/join/ > --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org