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Subject: Re: [PATCH v5 2/3] virtio: pci support virtqueue reset
On Fri, Oct 1, 2021 at 1:50 AM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote: > > PCI support virtqueue reset. > > virtio_pci_common_cfg add "queue_reset" to support virtqueue reset. > The driver uses this to selectively reset the queue. > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> > --- > content.tex | 32 ++++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/content.tex b/content.tex > index dd095f4..d014420 100644 > --- a/content.tex > +++ b/content.tex > @@ -901,6 +901,7 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > le64 queue_driver; /* read-write */ > le64 queue_device; /* read-write */ > le16 queue_notify_data; /* read-only for driver */ > + le16 queue_reset; /* read-write */ > }; > \end{lstlisting} > > @@ -980,6 +981,12 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > may benefit from providing another value, for example an internal virtqueue > identifier, or an internal offset related to the virtqueue number. > \end{note} > + > +\item[\field{queue_reset}] > + The driver uses this to selectively reset the queue. > + This field exists only if VIRTIO_F_RING_RESET has been > + negotiated. (see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}). > + > \end{description} > > \devicenormative{\paragraph}{Common configuration structure layout}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common configuration structure layout} > @@ -1021,6 +1028,22 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > > The device MUST present a 0 in \field{queue_enable} on reset. > > +If VIRTIO_F_RING_RESET has been negotiated, the device MUST present a 0 in > +\field{queue_enable} after the driver has reset the virtqueue via > +\field{queue_reset}. > + > +If VIRTIO_F_RING_RESET has been negotiated, the device MUST present a 0 in > +\field{queue_reset} on reset. > + > +If VIRTIO_F_RING_RESET has been negotiated, the device MUST present a 0 in > +\field{queue_reset} after the virtqueue is enabled with \field{queue_enable}. > + > +The device MUST reset the queue when 1 is written to \field{queue_reset}, and > +present a 1 in \field{queue_reset} after the queue has been reset, until the > +driver re-enables the queue via \field{queue_enable} or the device is reset. > +The device MAY present different default values after queue reset. I'm not sure I get the meaning of this. The device should stick to consistent default values. Thanks > +(see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}). > + > The device MUST present a 0 in \field{queue_size} if the virtqueue > corresponding to the current \field{queue_select} is unavailable. > > @@ -1045,6 +1068,15 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > > The driver MUST NOT write a 0 to \field{queue_enable}. > > +If VIRTIO_F_RING_RESET has been negotiated, after the driver writes 1 to > +\field{queue_reset} to reset the queue, it MUST verify that the queue > +has been reset by reading back \field{queue_reset} and ensuring that it > +is 1. The driver MAY re-enable the queue by writing a 1 to > +\field{queue_enable} after ensuring that the other virtqueue fields have > +been set up correctly. The driver MAY set driver-writeable queue configuration > +values to different values than those that were used before the queue reset. > +(see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}). > + > \subsubsection{Notification structure layout}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Notification capability} > > The notification location is found using the VIRTIO_PCI_CAP_NOTIFY_CFG > -- > 2.31.0 >
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