From: Parav Pandit <parav@nvidia.com>
To: "virtio-comment@lists.oasis-open.org"
<virtio-comment@lists.oasis-open.org>,
"mst@redhat.com" <mst@redhat.com>,
"cohuck@redhat.com" <cohuck@redhat.com>
Cc: "hengqi@linux.alibaba.com" <hengqi@linux.alibaba.com>,
"xuanzhuo@linux.alibaba.com" <xuanzhuo@linux.alibaba.com>,
Shahaf Shuler <shahafs@nvidia.com>
Subject: [virtio-comment] RE: [PATCH v2 0/2] Support enabling virtqueue after DRIVER_OK
Date: Tue, 26 Sep 2023 06:47:15 +0000 [thread overview]
Message-ID: <PH0PR12MB54812F26EDD240E8C14A6C91DCC3A@PH0PR12MB5481.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20230918173518.15900-1-parav@nvidia.com>
Hi Michael,
> From: Parav Pandit <parav@nvidia.com>
> Sent: Monday, September 18, 2023 11:05 PM
> Summary:
> ========
> This patch enables driver to create virtqueues after DRIVER_OK status bit is set.
>
> This patch take the inspiration from the thread [2] with credits to Eugenio PÃrez.
>
> Details:
> ========
> Currently, a virtqueue must be enabled before driver has set the DRIVER_OK
> status bit.
>
> spec citation to section "Driver Requirements: Device Initialization"
>
> "Perform device-specific setup, including discovery of virtqueues for the device,
> optional per-bus setup, reading and possibly writing the device’s virtio
> configuration space, and population of virtqueues."
>
> This implies that a virtqueue must be enabled before reaching the DRIVER_OK
> stage. There was no explicit mention about ability to enable the virtqueue after
> DRIVER_OK stage.
>
> In following usecases, creating a virtqueue after DRIVER_OK phase is desired.
>
> Use cases:
> =========
> 1. Dynamically create aq when administrative commands to be used.
> ate the net device tx/rxq when device is
> opened when deploying for a container.
> In a container, number of virtqueues to be used may be <= max queues.
> 3. Dynamically create flow filter queues of netdevice when
> ARFS or ethtool filters are enabled as listed in [1].
> 4. Dynamically create rtc functionality related read virtqueue only
> when net device when timestamping to be used.
> 5. When XDP program is set, one can create additional XDP specific
> queues without affecting existing queues.
>
> Hence, This patch introduces an existing queue enable and disable (aka reset)
> facility and a new feature bit to explicitly indicate such support by the device.
>
> With this feature, drivers can skip optional queues creation during driver init
> time. For example, a Linux net device driver can create/destroy the transmit and
> receive queues when net device's
> ndo_open() and ndo_stop() callbacks are invoked respectively.
>
> [1] https://lists.oasis-open.org/archives/virtio-
> comment/202308/msg00263.html
> [2] https://lists.oasis-open.org/archives/virtio-
> comment/202306/msg00097.html
>
> Patch summary:
> ==============
> patch-1 fixes to add virtqueue reset conformance references
> patch-2 adds VIRTIO_F_RING_DYNAMIC feature bit, requirements
>
> Please review.
>
> ---
> changelog:
> v1->v2:
> - fixed comments from Michael
> - reduced device and driver normatives (simplified)
> - replace 'a virtqueue' to 'the virtqueues'
> - reworded to remove 'interested'
> - avoided repeated 'device initialization text', replaced with
> DRIVER_OK status bit language
> - avoided confusing text around 'MAY' in the requirements
> - replaced 'the queue' to 'specific virtqueues'
> - replaced queue to virtqueue
> - simplified commit log to talk about msix
I have fixed the comments in v2.
Do you have any further comments of v2 from last week?
If not, I would like to post v3 with link to github issue and proceed to next step.
prev parent reply other threads:[~2023-09-26 6:47 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-18 17:35 [virtio-comment] [PATCH v2 0/2] Support enabling virtqueue after DRIVER_OK Parav Pandit
2023-09-18 17:35 ` [virtio-comment] [PATCH v2 1/2] conformance: Add missing virtqueue reset conformance references Parav Pandit
2023-09-18 17:35 ` [virtio-comment] [PATCH v2 2/2] content: Support enabling virtqueue after DRIVER_OK stage Parav Pandit
2023-09-26 6:47 ` Parav Pandit [this message]
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