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 D190FC04A6A for ; Tue, 15 Aug 2023 10:53:46 +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 EA3F675334 for ; Tue, 15 Aug 2023 10:53:44 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id C3E369863EE for ; Tue, 15 Aug 2023 10:53:44 +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 AA2A898633F; Tue, 15 Aug 2023 10:53:44 +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 97C6F98634B; Tue, 15 Aug 2023 10:53:43 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10802"; a="372248963" X-IronPort-AV: E=Sophos;i="6.01,174,1684825200"; d="scan'208";a="372248963" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10802"; a="683616528" X-IronPort-AV: E=Sophos;i="6.01,174,1684825200"; d="scan'208";a="683616528" Message-ID: <40b16480-8b59-4b97-a079-33b477fcb37c@intel.com> Date: Tue, 15 Aug 2023 18:53:35 +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/102.14.0 Content-Language: en-US To: Stefan Hajnoczi Cc: jasowang@redhat.com, mst@redhat.com, eperezma@redhat.com, cohuck@redhat.com, virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org References: <20230814192904.30062-1-lingshan.zhu@intel.com> <20230814192904.30062-3-lingshan.zhu@intel.com> <20230814144941.GE3146793@fedora> From: "Zhu, Lingshan" In-Reply-To: <20230814144941.GE3146793@fedora> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [virtio-dev] [RFC PATCH 2/5] virtio: introduce vq state as basic facility On 8/14/2023 10:49 PM, Stefan Hajnoczi wrote: > On Tue, Aug 15, 2023 at 03:29:01AM +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 implemention. 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). 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: Jason Wang >> Signed-off-by: Zhu Lingshan >> --- >> content.tex | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 62 insertions(+) >> >> diff --git a/content.tex b/content.tex >> index 1bb4401..074f43e 100644 >> --- a/content.tex >> +++ b/content.tex >> @@ -516,6 +516,68 @@ \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 is 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 virtqueue state that is used by > "two bytes of virtqueue state" Yes, will fix > >> +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. >> + >> +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. > Please specify the non-packed case: > > "When VIRTIO_RING_F_PACKED is not negotiated, the 16-bit value is always > 0." we did not define the used_state for non-packed vqs in this series. I will define this in the next version. and Say it is always 0 if VIRTIO_F_PACKED is not negotiated. > >> + >> +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 next > "device writes the next" Yes, will fix Thanks > >> +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}. >> + >> \input{admin.tex} >> >> \chapter{General Initialization And Device Operation}\label{sec:General Initialization And Device Operation} >> -- >> 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 >> --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org