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 63FBAC001DE for ; Fri, 18 Aug 2023 09:44:35 +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 99CF97E98E for ; Fri, 18 Aug 2023 09:44:34 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 7F76F98652B for ; Fri, 18 Aug 2023 09:44:34 +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 72F33986447; Fri, 18 Aug 2023 09:44:34 +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 5CF8D98643F; Fri, 18 Aug 2023 09:44:30 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10805"; a="373042290" X-IronPort-AV: E=Sophos;i="6.01,182,1684825200"; d="scan'208";a="373042290" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10805"; a="981594688" X-IronPort-AV: E=Sophos;i="6.01,182,1684825200"; d="scan'208";a="981594688" Message-ID: <23b9082d-050a-6f82-754e-d309c48972d5@intel.com> Date: Fri, 18 Aug 2023 17:44:23 +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: Eugenio Perez Martin Cc: Jason Wang , mst@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> <20230814192904.30062-5-lingshan.zhu@intel.com> <8ce92e00-39f9-3e99-96e2-5599588869e3@intel.com> From: "Zhu, Lingshan" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [RFC PATCH 4/5] virtqueue: constraints for virtqueue state On 8/17/2023 11:19 PM, Eugenio Perez Martin wrote: > On Tue, Aug 15, 2023 at 1:30 PM Zhu, Lingshan wrote: >> >> >> On 8/15/2023 8:34 AM, Jason Wang wrote: >>> On Mon, Aug 14, 2023 at 7:29 PM Zhu Lingshan wrote: >>>> This commit specifies the constraints of the virtqueue state, >>>> and the actions should be taken by the device when SUSPEND >>>> and DRIVER_OK is set >>>> >>>> Signed-off-by: Jason Wang >>>> Signed-off-by: Zhu Lingshan >>>> --- >>>> content.tex | 31 +++++++++++++++++++++++++++++++ >>>> 1 file changed, 31 insertions(+) >>>> >>>> diff --git a/content.tex b/content.tex >>>> index 43bd5de..f6ac581 100644 >>>> --- a/content.tex >>>> +++ b/content.tex >>>> @@ -587,6 +587,37 @@ \subsection{\field{Used State} Field} >>>> >>>> See also \ref{sec:Packed Virtqueues / Driver and Device Ring Wrap Counters}. >>>> >>>> +\drivernormative{\subsection}{Virtqueue State}{Basic Facilities of a Virtio Device / Virtqueue State} >>>> + >>>> +If VIRTIO_F_QUEUE_STATE has been negotiated, the driver MUST set SUSPEND in \field{device status} >>>> +first before getting or setting Virtqueue State of any virtqueues. >>> I don't get why this is a must. It could be useful for debugging. >> To avoid race conditions with the device and make the device >> implementation easier >>>> + >>>> +If VIRTIO_F_QUEUE_STATE has been negotiaged but VIRTIO_RING_F_PACKED not been negotiated, >>> typo >> yes >>>> +the driver MUST NOT access \field{Used State} of any virtqueues, it should use the >>>> +used index in the used ring. >>>> + >>>> +\devicenormative{\subsection}{Virtqueue State}{Basic Facilities of a Virtio Device / Virtqueue State} >>>> + >>>> +If VIRTIO_F_QUEUE_STATE has been negotiated but SUSPEND is not set in \field{device status}, >>>> +the device MUST ignore any accesses against Virtqueue State of any virtqueues. >>> Btw, do we need to clarify the behavior of ring reset after suspending? >> I think once suspended, the device should ignore resetting a queue > Actually shadow virtqueue could benefit from the ability to change vq > properties (addresses) while the device is suspended, and then just > resume it. I've been told that ring reset is overkill for that. If ring reset is overkill, is SUSPEND even more overkill? > > But probably it is better to address it on top, with another feature flag. I think if we want to changing the vq properties, there must be a mechanism to stop the queue then resume the queue. How about allow setting queue_enable = 0 to stop it and =1 to resume and force it reinitialize? Thanks Zhu Lingshan > >>>> + >>>> +When VIRTIO_F_QUEUE_STATE has been negotiated but VIRTIO_RING_F_PACKED is not, >>>> +the device MUST ignore any accesses against \field{Used State}. >>>> + >>>> +If VIRTIO_F_QUEUE_STATE has been negotiaged, the device MUST reset >>>> +the Virtqueue State of every virtqueue upon a reset. >>> Need to define the meaning of "reset" this is important for packed virtqueue. >> I will remove this as Stefan suggested. >>>> + >>>> +If VIRTIO_F_QUEUE_STATE and VIRTIO_RING_F_PACKED have been negotiaged, when SUSPEND is set, >>>> +the device MUST record the Virtqueue State of every enabled virtqueue >>>> +in \field{Available State} and \field{Used State} respectively, >>>> +and correspondingly restore the Virtqueue State of every enabled virtqueue >>>> +from \field{Avaiable State} and \field{Used State} when DRIVER_OK is set. >>> We can just let the device report those states in any case then we >>> don't need to care about those details, or did you see any blockers? >> Agree, I will add the definition of used_state of splitted vq in the >> next version >> >> Thanks >>> Thanks >>> >>>> + >>>> +If VIRTIO_F_QUEUE_STATE has been negotiated but VIRTIO_RING_F_PACKED has been not, when SUSPEND is set, >>>> +the device MUST record the available state of every enabled virtqueue in \field{Available State}, >>>> +and restore the available state of every enabled virtqueue from \field{Avaiable State} >>>> +when DRIVER_OK is set. >>>> + >>>> \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