From: Parav Pandit <parav@nvidia.com>
To: <virtio-comment@lists.oasis-open.org>, <mst@redhat.com>,
<cohuck@redhat.com>
Cc: <hengqi@linux.alibaba.com>, <xuanzhuo@linux.alibaba.com>,
<shahafs@nvidia.com>, Parav Pandit <parav@nvidia.com>
Subject: [virtio-comment] [PATCH v4 0/2] Support enabling virtqueue after DRIVER_OK
Date: Tue, 17 Oct 2023 17:31:33 +0300 [thread overview]
Message-ID: <20231017143135.758523-1-parav@nvidia.com> (raw)
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.
Fixes: https://github.com/oasis-tcs/virtio-spec/issues/177
---
changelog:
v3->v4:
- addressed comments from Cornelia
- reworded description for _DYNAMIC negotiated case
- replaced article the to a
- reworded driver normative for _DYNAMIC negotiated case
- replaced 'required' with 'desired'
- extended description for skip entirely to skip or do partial init
- removed article the on plural virtqueues
v2->v3:
- github issue link updated
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
v0->v1:
- fixed comments from Xuan
- removed blank lines
- fixed wrong requirement link to device in driver section
Parav Pandit (2):
conformance: Add missing virtqueue reset conformance references
content: Support enabling virtqueue after DRIVER_OK stage
conformance.tex | 4 ++++
content.tex | 44 +++++++++++++++++++++++++++++++++++++++++---
2 files changed, 45 insertions(+), 3 deletions(-)
--
2.34.1
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next reply other threads:[~2023-10-17 14:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-17 14:31 Parav Pandit [this message]
2023-10-17 14:31 ` [virtio-comment] [PATCH v4 1/2] conformance: Add missing virtqueue reset conformance references Parav Pandit
2023-10-17 14:31 ` [virtio-comment] [PATCH v4 2/2] content: Support enabling virtqueue after DRIVER_OK stage Parav Pandit
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