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 296D5C0015E for ; Wed, 16 Aug 2023 02:20:50 +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 91A24C624E for ; Wed, 16 Aug 2023 02:20:49 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 8AD6998642C for ; Wed, 16 Aug 2023 02:20:49 +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 7E21D9863F0; Wed, 16 Aug 2023 02:20:49 +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 6CFC69863D1; Wed, 16 Aug 2023 02:20:46 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10803"; a="458774975" X-IronPort-AV: E=Sophos;i="6.01,175,1684825200"; d="scan'208,217";a="458774975" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10803"; a="683872473" X-IronPort-AV: E=Sophos;i="6.01,175,1684825200"; d="scan'208,217";a="683872473" Content-Type: multipart/alternative; boundary="------------USCDa0JnZ7N3s1imMawTHyAg" Message-ID: <02ce48ed-6804-933c-9cf5-3e4123d12530@intel.com> Date: Wed, 16 Aug 2023 10:20:39 +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> <47cc93ea-47e9-6390-4752-02f10f2bdc6e@intel.com> From: "Zhu, Lingshan" In-Reply-To: Subject: [virtio-dev] Re: [virtio-comment] Re: [RFC PATCH 1/5] virtio: introduce SUSPEND bit in device status --------------USCDa0JnZ7N3s1imMawTHyAg Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/16/2023 10:05 AM, Jason Wang wrote: > On Tue, Aug 15, 2023 at 6:50 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. >>>> >>>>> 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? >>>> >>>>> + >>>>> +The deivce MUST ignore SUSPEND if VIRTIO_F_SUSPEND is not negotiated. >>>> typo. >>>> >>>> Thanks >>> Btw, it's not clear to me if driver is allowed to clear this bit. >> To allow terminate a live migration process or resume from a failed live >> migration, >> we allow DRIVER_OK to clear SUSPEND, in patch 1. > Does this imply DRIVER_OK is cleared during SUSPEND? This seems more > complicated than simply allowing clearing this bit? No, SUSPEND does not clears DRIVER_OK, only DRIVER_OK clears SUSPEND. The spec says: The driver MUST NOT clear a device status bit. So I think maybe it's better let the device clears SUSPEND. Thanks > > Thanks > >> 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 >>>>> >> >> 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/ >> --------------USCDa0JnZ7N3s1imMawTHyAg Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit

On 8/16/2023 10:05 AM, Jason Wang wrote:
On Tue, Aug 15, 2023 at 6:50 PM Zhu, Lingshan <lingshan.zhu@intel.com> wrote:



On 8/15/2023 8:37 AM, Jason Wang wrote:

On Tue, Aug 15, 2023 at 8:26 AM Jason Wang <jasowang@redhat.com> wrote:

On Mon, Aug 14, 2023 at 7:29 PM Zhu Lingshan <lingshan.zhu@intel.com> 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.


Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio PÃrez <eperezma@redhat.com>
Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
---
  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?


+
+The deivce MUST ignore SUSPEND if VIRTIO_F_SUSPEND is not negotiated.

typo.

Thanks

Btw, it's not clear to me if driver is allowed to clear this bit.

To allow terminate a live migration process or resume from a failed live
migration,
we allow DRIVER_OK to clear SUSPEND, in patch 1.

Does this imply DRIVER_OK is cleared during SUSPEND? This seems more
complicated than simply allowing clearing this bit?
No, SUSPEND does not clears DRIVER_OK, only DRIVER_OK clears SUSPEND.
The spec says: The driver MUST NOT clear a device status bit.
So I think maybe it's better let the device clears SUSPEND.

Thanks 

Thanks


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



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