[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: Re: [virtio-dev] Re: [PATCH v4 1/3] virtio: introduce virtqueue reset as basic facility
On Thu, Sep 30, 2021 at 12:24 AM Cornelia Huck <cohuck@redhat.com> wrote: > > On Wed, Sep 29 2021, Jason Wang <jasowang@redhat.com> wrote: > > > On Wed, Sep 29, 2021 at 10:01 AM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > >> > >> On Tue, 28 Sep 2021 12:06:01 +0200, Cornelia Huck <cohuck@redhat.com> wrote: > >> > On Tue, Sep 28 2021, Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > >> > > >> > > 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 | 45 +++++++++++++++++++++++++++++++++++++++++++++ > >> > > 1 file changed, 45 insertions(+) > >> > > > >> > > diff --git a/content.tex b/content.tex > >> > > index 37c45d3..05b05ba 100644 > >> > > --- a/content.tex > >> > > +++ b/content.tex > >> > > @@ -407,6 +407,47 @@ \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]}. > >> > > > > > > Btw, we need to add this into the section of "Virtqueues" > > > Hm, isn't it already? Looks not, this follows the section of "Exporting Objects". > > > > >> > > +\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 reset a queue > >> > > +first, and then re-enable the queue. The re-enable part is optional. > >> > > >> > Maybe > >> > > >> > "The driver first resets a queue and can afterwards optionally re-enable > >> > it." > >> > > >> > ? > >> > > >> > > + > >> > > +\subsection{Virtqueue Reset}\label{sec:Virtqueues / Virtqueue Reset / Virtqueue Reset} > >> > > + > >> > > +\devicenormative{\subsubsection}{Virtqueue Reset}{Virtqueues / Virtqueue Reset / Virtqueue Reset} > >> > > + > >> > > +After a queue has been reset by the driver, the device MUST NOT execute > >> > > +any requests from that virtqueue, or notify the driver for it. > >> > > + > >> > > +The device MUST re-initialize any state of a virtqueue that has been > >> > > +reset, including available and used state. > > > > Maybe "The device must reset any state..." > > "reset to defaults"? Otherwise, it seems a bit redundant. Right. > > > > >> > > + > >> > > +\drivernormative{\subsubsection}{Virtqueue Reset}{Virtqueues / Virtqueue Reset / Virtqueue Reset} > >> > > + > >> > > +After the driver tell the device to reset a queue, the driver MUST verify that > >> > > >> > s/tell/tells/ (may have been my typo...) > >> > > >> > > +the queue has actually been reset. > >> > > + > >> > > +After the queue has been successfully reset, the driver MAY release any > >> > > +resource associated with that virtqueue. > >> > > + > >> > > +\subsection{Virtqueue Re-enable}\label{sec:Virtqueues / Virtqueue Reset / Virtqueue Re-enable} > >> > > + > >> > > +This process is the same as the initialization process of a single queue during > >> > > +the initialization of the entire device. > >> > > + > >> > > +\devicenormative{\subsubsection}{Virtqueue Re-enable}{Virtqueues / Virtqueue Reset / Virtqueue Re-enable} > >> > > + > >> > > +The device MUST receive the new configuration from the driver. (i.e. the maximum > >> > > +Queue Size.) > >> > > >> > Maybe > >> > > >> > "The device MUST observe any queue configuration that may have been > >> > changed by the driver, like the maximum queue size." > >> > > >> > Although I'm not sure about 'observe'. Anybody have a better term? > > > > I wonder if this is implied in the queue_enable or we need to explain > > the semantics of "queue_enable" instead of here. Considering we list > > queue reset and basic facility, we need to explicitly add queue enable > > into the basic facility first. > > I'm wondering whether we need to clarify explicitly that the driver may > re-enable the queue with different parameters? I think we need, my understanding is that at least the driver can set a different queue address etc. > > > > >> > > >> > > + > >> > > +\drivernormative{\subsubsection}{Virtqueue Re-enable}{Virtqueues / Virtqueue Reset / Virtqueue Re-enable} > >> > > + > >> > > +The driver MUST apply for resources, set new configuration to the device, and > >> > > +finally activate the device. > >> > > >> > Maybe > >> > > >> > "When re-enabling a queue, the driver MUST configure the queue resources > >> > as during initial virtqueue discovery, but optionally with different > >> > parameters." > >> > > >> > ? > > > > If we make the queue enablement as a subsection, we can move this > > there. Then we don't need to differ enable and re-enable. > > Yes, I notice we are a bit light on details about queue > discovery/enablement. It's basically all in the transport-specific sections. > Yes. Thanks
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]