From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 0C2C39862F0 for ; Mon, 27 Sep 2021 14:51:49 +0000 (UTC) From: Cornelia Huck In-Reply-To: <20210927123153.20242-3-xuanzhuo@linux.alibaba.com> References: <20210927123153.20242-1-xuanzhuo@linux.alibaba.com> <20210927123153.20242-3-xuanzhuo@linux.alibaba.com> Date: Mon, 27 Sep 2021 16:51:43 +0200 Message-ID: <87sfxqcbr4.fsf@redhat.com> MIME-Version: 1.0 Subject: Re: [virtio-dev] [PATCH v3 2/2] virtio: pci support virtqueue reset Content-Type: text/plain To: Xuan Zhuo , jasowang@redhat.com Cc: virtio-dev@lists.oasis-open.org List-ID: On Mon, Sep 27 2021, Xuan Zhuo 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 > --- > content.tex | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/content.tex b/content.tex > index 603b1f1..35228dc 100644 > --- a/content.tex > +++ b/content.tex > @@ -896,6 +896,7 @@ \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} > > @@ -975,6 +976,12 @@ \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: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} > @@ -1016,6 +1023,14 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > > The device MUST present a 0 in \field{queue_enable} on reset. > > +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} until the > +queue is enabled with \field{queue_enable}. (see \ref{sec:Virtqueues / Virtqueue Reset}). "present a 1 in \field{queue_reset} after the queue has been reset, until the driver re-enables the queue via \field{queue_enable}" ? I suppose queue_reset is reset to 0 when the whole device is reset? > + > +The device MUST present a 0 in \field{queue_enable} after the virtqueue is reset > +with \field{queue_reset}. (see \ref{sec:Virtqueues / Virtqueue Reset}). "after the driver has reset the virtqueue via \field{queue_reset}" ? This section should probably also refer to the feature bit at least once? > + > The device MUST present a 0 in \field{queue_size} if the virtqueue > corresponding to the current \field{queue_select} is unavailable. > > @@ -1040,6 +1055,12 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > > The driver MUST NOT write a 0 to \field{queue_enable}. > > +If the VIRTIO_F_RING_RESET feature bit is negotiated, the driver can stop using > +the queue by writing a 1 to \field{queue_reset} and MUST read the value back to > +ensure synchronization. Then optionally re-enable the queue by writing a 1 to > +\field{queue_enable} after configuring the other virtqueue fields. (see > +\ref{sec:Virtqueues / Virtqueue Reset}). "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." ? > + > \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 MMIO can probably use a similar mechanism. For CCW, maybe we can add a payload to the existing RESET command if the feature has been negotiated; the queue can be re-enabled by the normal READ_VQ_CONF/SET_VQ procedure. I have not yet thought that through. --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org