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Subject: [PATCH v3 1/2] virtio: introduce virtqueue reset as basic facility
This patch allows the driver to reset a queue individually. This is very common on general network equipment. By disabling a queue, you can quickly reclaim the buffer currently on the queue. If necessary, we can reinitialize the queue separately. For example, when virtio-net implements support for AF_XDP, we need to disable a queue to release all the original buffers when AF_XDP setup. And quickly release all the AF_XDP buffers that have been placed in the queue when AF_XDP exits. Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> --- content.tex | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) diff --git a/content.tex b/content.tex index 37c45d3..603b1f1 100644 --- a/content.tex +++ b/content.tex @@ -407,6 +407,43 @@ \section{Exporting Objects}\label{sec:Basic Facilities of a Virtio Device / Expo types. It is RECOMMENDED that devices generate version 4 UUIDs as specified by \hyperref[intro:rfc4122]{[RFC4122]}. +\section{Virtqueue Reset}\label{sec:Virtqueues / Virtqueue Reset} + +When VIRTIO_F_RING_RESET is negotiated, the driver can reset a virtqueue +individually. The way to reset the virtqueue is transport specific. + +Virtqueue reset is divided into two parts. The driver MUST reset stop a queue +first, and then re-enable the queue. The re-enable part is optional. + +\devicenormative{\subsection}{Virtqueue Reset Stop}{Virtqueues / Virtqueue Reset} +The device MUST not executes the requests from this virtqueue, and notify the +driver. + +And the device MUST initialize all states of this virtqueue, including the +available state and the used state. + +\drivernormative{\subsection}{Virtqueue Reset Stop}{Virtqueues / Virtqueue Reset} + +The driver MUST first notify the device and confirm that we have successfully +stopped a queue. + +Then the driver can release all the resources occupied by this virtqueue. +And reinitialize the state of this queue. + +\devicenormative{\subsection}{Virtqueue Reset Re-enable}{Virtqueues / Virtqueue Reset} + +This process is the same as the initialization process of a single queue during +the initialization of the entire device. After the device has accepted all the +configuration from the driver, it will start working under the notification of the +driver. + +\drivernormative{\subsection}{Virtqueue Reset Re-enable}{Virtqueues / Virtqueue Reset} + +This process is the same as the initialization process of a single queue during +the entire device initialization process. After the driver allocates resources +and completes the configuration of the queue status, it notifies the device to +start working. + \chapter{General Initialization And Device Operation}\label{sec:General Initialization And Device Operation} We start with an overview of device initialization, then expand on the @@ -6673,6 +6710,10 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved Feature Bits} transport specific. For more details about driver notifications over PCI see \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Available Buffer Notifications}. + \item[VIRTIO_F_RING_RESET(40)] This feature indicates + that the driver can reset a queue individually. + See \ref{sec:Virtqueues / Virtqueue Reset}. + \end{description} \drivernormative{\section}{Reserved Feature Bits}{Reserved Feature Bits} -- 2.31.0
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