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 C359CC001DE for ; Wed, 16 Aug 2023 02:17:29 +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 33CA071C8E for ; Wed, 16 Aug 2023 02:17:29 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 2892098643D for ; Wed, 16 Aug 2023 02:17:29 +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 1C87F9863EF; Wed, 16 Aug 2023 02:17:29 +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 0BAC89863D1; Wed, 16 Aug 2023 02:17:25 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10803"; a="375192647" X-IronPort-AV: E=Sophos;i="6.01,175,1684825200"; d="scan'208";a="375192647" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10803"; a="763476256" X-IronPort-AV: E=Sophos;i="6.01,175,1684825200"; d="scan'208";a="763476256" Message-ID: <2d0d78ed-fd2b-fe74-05b2-15abf0441e72@intel.com> Date: Wed, 16 Aug 2023 10:17:17 +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: Jason Wang Cc: 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> <20230814192904.30062-2-lingshan.zhu@intel.com> <6d41cf4f-8cc2-6bad-7b22-2369fd6a620c@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 1/5] virtio: introduce SUSPEND bit in device status On 8/16/2023 9:58 AM, Jason Wang wrote: > On Tue, Aug 15, 2023 at 6:48 PM Zhu, Lingshan wrote: >> >> >> On 8/15/2023 8:37 AM, Jason Wang wrote: >>> On Tue, Aug 15, 2023 at 8:26 AM Jason Wang wrote: >>>> On Mon, Aug 14, 2023 at 7:29 PM Zhu Lingshan wrote: >>>>> This patch introudces 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 stablize the device states and virtqueue states. >>>>> >>>>> Its main use case is live migration. >>>> I think patch 3 needs to be squashed into this one. >> Patch 3 mentions Virtqueue State that is introduced in patch 2, > Ok, so let's reorder the let patch 2 come first. OK, I can work on that Thanks > > Thanks > >> so I think patch 3 should placed after patch 2. >> >> Thanks >>>>> Signed-off-by: Jason Wang >>>>> Signed-off-by: Eugenio PÃrez >>>>> Signed-off-by: Zhu Lingshan >>>>> --- >>>>> content.tex | 18 ++++++++++++++++++ >>>>> 1 file changed, 18 insertions(+) >>>>> >>>>> diff --git a/content.tex b/content.tex >>>>> index 0a62dce..1bb4401 100644 >>>>> --- a/content.tex >>>>> +++ b/content.tex >>>>> @@ -47,6 +47,9 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev >>>>> \item[DRIVER_OK (4)] Indicates that the driver is set up and ready to >>>>> drive the device. >>>>> >>>>> +\item[SUSPEND (16)] When VIRTIO_F_SUSPEND is negotiated, indicates that the >>>>> + device has been suspended by the driver. >>>>> + >>>>> \item[DEVICE_NEEDS_RESET (64)] Indicates that the device has experienced >>>>> an error from which it can't recover. >>>>> \end{description} >>>>> @@ -73,6 +76,10 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev >>>>> recover by issuing a reset. >>>>> \end{note} >>>>> >>>>> +The driver MUST NOT set SUSPEND if FEATURES_OK is not set. >>>>> + >>>>> +When set 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 +89,13 @@ \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. >>>> Is there any value to allow SUSPEND to be set without DRIVER_OK? >> If live migration happens when the guest initializing the device, >> maybe the guest driver has already configured some virtqueues or >> modified the config space. At that point, We should allow to suspend >> the device, because the hypervisor should not reset the device at >> that moment. >> >> SUSPEND requires FEATURES_OK because VIRTIO_F_SUSPEND has to be negotiated. >>>>> + >>>>> +The deivce MUST ignore SUSPEND if VIRTIO_F_SUSPEND is not negotiated. >>>> typo. >> Yes >>>> Thanks >>> Btw, it's not clear to me if driver is allowed to clear this bit. >> Patch 1 mentions that DRIVER_OK clears SUSPEND, so that the driver >> can resume the device if LM fails. >> >> Thanks >>> Thanks >>> >>>>> + >>>>> +If VIRTIO_F_SUSPEND is negotiated and SUSPEND is set, the device MUST clear SUSPEND >>>>> +and resumes operation upon DRIVER_OK. >>>>> + >>>>> \section{Feature Bits}\label{sec:Basic Facilities of a Virtio Device / Feature Bits} >>>>> >>>>> Each virtio device offers all the features it understands. During >>>>> @@ -872,6 +886,10 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved Feature Bits} >>>>> \ref{devicenormative:Basic Facilities of a Virtio Device / Feature Bits} for >>>>> handling features reserved for future use. >>>>> >>>>> + \item[VIRTIO_F_SUSPEND(41)] 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 >>>>> --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org