On Wed, Jul 12, 2023 at 07:44:01PM +0800, Xuan Zhuo wrote:
> On Wed, 12 Jul 2023 07:34:38 -0400, "Michael S. Tsirkin" <[email protected]>
> wrote:
> > On Tue, Mar 15, 2022 at 11:24:02AM +0800, Xuan Zhuo wrote:
> > > This patch allows the driver to obtain some statistics from the device.
> > >
> > > In the back-end implementation, we can count a lot of such information,
> > > which can be used for debugging and judging the running status of the
> > > back-end. We hope to directly display it to the user through ethtool.
> > >
> > > To get stats atomically, try to get stats for all queue pairs in one
> > > command.
> > >
> > > Signed-off-by: Xuan Zhuo <[email protected]>
> > > Suggested-by: Michael S. Tsirkin <[email protected]>
> >
> > Functionally, I think this is close to ok now. But the text needs
> > of work. Are you trying to target 1.3 with this?
>
> I personally worry about that 1.3 may be too late, if possible, I would like
> to
> respond as soon as possible.
>
> I really don't really care if it can get into 1.3 or not but I do hope that
> this
> can be done as soon as possible.
>
> Thanks.
Yes we were supposed to freeze for 1.3. This change can be merged on a
main branch after 1.3 forks and is under review.
>
> >
> > Feedback from other hw vendors would be nice. Parav could you take
> > a look and say whether the list of counters seems rich enough for
> > you? Any counters you'd like to add?
> >
> >
> > > ---
> > > conformance.tex | 2 +
> > > content.tex | 406 +++++++++++++++++++++++++++++++++++++++++++++++-
> > > 2 files changed, 405 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/conformance.tex b/conformance.tex
> > > index 42f8537..c67f877 100644
> > > --- a/conformance.tex
> > > +++ b/conformance.tex
> > > @@ -142,6 +142,7 @@ \section{Conformance Targets}\label{sec:Conformance /
> > > Conformance Targets}
> > > \item \ref{drivernormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Automatic receive steering in multiqueue
> > > mode}
> > > \item \ref{drivernormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Offloads State Configuration / Setting
> > > Offloads State}
> > > \item \ref{drivernormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Receive-side scaling (RSS) }
> > > +\item \ref{drivernormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Device Stats}
> > > \end{itemize}
> > >
> > > \conformance{\subsection}{Block Driver
> > > Conformance}\label{sec:Conformance / Driver Conformance / Block Driver
> > > Conformance}
> > > @@ -401,6 +402,7 @@ \section{Conformance Targets}\label{sec:Conformance /
> > > Conformance Targets}
> > > \item \ref{devicenormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Gratuitous Packet Sending}
> > > \item \ref{devicenormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Automatic receive steering in multiqueue
> > > mode}
> > > \item \ref{devicenormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS
> > > processing}
> > > +\item \ref{devicenormative:Device Types / Network Device / Device
> > > Operation / Control Virtqueue / Device Stats}
> > > \end{itemize}
> > >
> > > \conformance{\subsection}{Block Device
> > > Conformance}\label{sec:Conformance / Device Conformance / Block Device
> > > Conformance}
> > > diff --git a/content.tex b/content.tex
> > > index c6f116c..81f325d 100644
> > > --- a/content.tex
> > > +++ b/content.tex
> > > @@ -3092,6 +3092,9 @@ \subsection{Feature bits}\label{sec:Device Types /
> > > Network Device / Feature bits
> > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control
> > > channel.
> > >
> > > +\item[VIRTIO_NET_F_CTRL_STATS(55)] Device can provide device-level
> > > statistics
> > > + to the driver through the control channel.
> > > +
> > > \item[VIRTIO_NET_F_HOST_USO (56)] Device can receive USO packets. Unlike
> > > UFO
> > > (fragmenting the packet) the USO splits large UDP packet
> > > to several segments when each of these smaller packets has UDP header.
> > > @@ -3137,6 +3140,7 @@ \subsubsection{Feature bit
> > > requirements}\label{sec:Device Types / Network Device
> > > \item[VIRTIO_NET_F_GUEST_ANNOUNCE] Requires VIRTIO_NET_F_CTRL_VQ.
> > > \item[VIRTIO_NET_F_MQ] Requires VIRTIO_NET_F_CTRL_VQ.
> > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR] Requires VIRTIO_NET_F_CTRL_VQ.
> > > +\item[VIRTIO_NET_F_CTRL_STATS] Requires VIRTIO_NET_F_CTRL_VQ.
> > > \item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or
> > > VIRTIO_NET_F_HOST_TSO6.
> > > \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ.
> > > \end{description}
> > > @@ -4015,6 +4019,7 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > > Types / Network Device / Devi
> > > u8 command;
> > > u8 command-specific-data[];
> > > u8 ack;
> > > + u8 command-specific-data-reply[];
> > > };
> > >
> > > /* ack values */
> > > @@ -4023,9 +4028,11 @@ \subsubsection{Control Virtqueue}\label{sec:Device
> > > Types / Network Device / Devi
> > > \end{lstlisting}
> > >
> > > The \field{class}, \field{command} and command-specific-data are set by
> > > the
> > > -driver, and the device sets the \field{ack} byte. There is little it can
> > > -do except issue a diagnostic if \field{ack} is not
> > > -VIRTIO_NET_OK.
> > > +driver, and the device sets the \field{ack} byte and optionally
> > > +\field{command-specific-data-reply}. There is little the driver can
> > > +do except issue a diagnostic if \field{ack} is not VIRTIO_NET_OK.
> > > +
> > > +The command VIRTIO_NET_CTRL_STATS_GET contains
> > > \field{command-specific-data-reply}.
> > >
> > > \paragraph{Packet Receive Filtering}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Packet Receive Filtering}
> > > \label{sec:Device Types / Network Device / Device Operation / Control
> > > Virtqueue / Setting Promiscuous Mode}%old label for latexdiff
> > > @@ -4471,6 +4478,399 @@ \subsubsection{Control
> > > Virtqueue}\label{sec:Device Types / Network Device / Devi
> > > according to the native endian of the guest rather than
> > > (necessarily when not using the legacy interface) little-endian.
> > >
> > > +\paragraph{Device Stats}\label{sec:Device Types / Network Device /
> > > Device Operation / Control Virtqueue / Device Stats}
> > > +
> > > +If the VIRTIO_NET_F_CTRL_STATS feature is negotiated, the driver can
> > > +get the device stats from the device in
> > > \field{command-specific-data-reply}.
> > > +
> > > +To get the stats, the following definitions are used:
> > > +\begin{lstlisting}
> > > +#define VIRTIO_NET_CTRL_STATS 6
> > > +#define VIRTIO_NET_CTRL_STATS_GET 0
> > > +
> > > +#define VIRTIO_NET_STATS_TYPE_CVQ 0
> > > +#define VIRTIO_NET_STATS_TYPE_RX_BASIC 1
> > > +#define VIRTIO_NET_STATS_TYPE_RX_CSUM 2
> > > +#define VIRTIO_NET_STATS_TYPE_RX_GSO 3
> > > +#define VIRTIO_NET_STATS_TYPE_RX_RESET 4
> > > +#define VIRTIO_NET_STATS_TYPE_TX_BASIC 5
> > > +#define VIRTIO_NET_STATS_TYPE_TX_CSUM 6
> > > +#define VIRTIO_NET_STATS_TYPE_TX_GSO 7
> > > +#define VIRTIO_NET_STATS_TYPE_TX_RESET 8
> > > +
> > > +\end{lstlisting}
> > > +
> > > +Use the command VIRTIO_NET_CTRL_STATS_GET and
> > > \field{command-specific-data}
> > > +containing struct virtio_net_ctrl_queue_stats to get the device stats.
> > > +The result is returned by \field{command-specific-data-reply}.
> > > +The stats ware returned in the order of the type specified in the
> > > +\field{virtio_net_ctrl_queue_stats}.
> > > +
> > > +The following layout structures are used:
> > > +
> > > +\field{command-specific-data}
> > > +\begin{lstlisting}
> > > +struct virtio_net_ctrl_queue_stats {
> > > + u16 nstats;
> > > + struct {
> > > + u16 queue_num;
> > > + u16 type;
> > > + } stats[];
> > > +};
> > > +\end{lstlisting}
> > > +
> > > +\field{command-specific-data-reply}
> > > +\begin{lstlisting}
> > > +struct virtio_net_stats_cvq {
> > > + le64 command_num;
> > > + le64 ok_num;
> > > +};
> > > +
> > > +struct virtio_net_stats_rx_basic {
> > > + le64 rx_packets;
> > > + le64 rx_bytes;
> > > +
> > > + le64 rx_notification;
> > > + le64 rx_interrupt;
> > > +
> > > + le64 rx_drop;
> > > + le64 rx_drop_overruns;
> > > +};
> > > +
> > > +struct virtio_net_stats_rx_csum {
> > > + le64 rx_csum_valid;
> > > + le64 rx_needs_csum;
> > > + le64 rx_csum_bad;
> > > + le64 rx_csum_none;
> > > +};
> > > +
> > > +struct virtio_net_stats_rx_gso {
> > > + le64 rx_gso_packets;
> > > + le64 rx_gso_bytes;
> > > + le64 rx_gso_packets_coalesced;
> > > + le64 rx_gso_bytes_coalesced;
> > > + le64 rx_gso_segments;
> > > + le64 rx_gso_segments_bytes;
> > > +};
> > > +
> > > +struct virtio_net_stats_rx_reset {
> > > + le64 rx_reset;
> > > +};
> > > +
> > > +struct virtio_net_stats_tx_basic {
> > > + le64 tx_packets;
> > > + le64 tx_bytes;
> > > +
> > > + le64 tx_notification;
> > > + le64 tx_interrupt;
> > > +
> > > + le64 tx_drop;
> > > + le64 tx_drop_malformed;
> > > +};
> > > +
> > > +struct virtio_net_stats_tx_csum {
> > > + le64 tx_csum_none;
> > > + le64 tx_needs_csum;
> > > +};
> > > +
> > > +struct virtio_net_stats_tx_gso {
> > > + le64 tx_gso_packets;
> > > + le64 tx_gso_bytes;
> > > + le64 tx_gso_packets_split;
> > > + le64 tx_gso_bytes_split;
> > > + le64 tx_gso_segments;
> > > + le64 tx_gso_segments_bytes;
> > > +};
> > > +
> > > +struct virtio_net_stats_tx_reset {
> > > + le64 tx_reset;
> > > +};
> > > +
> > > +\end{lstlisting}
> > > +
> > > +\begin{description}
> > > + \item [nstats]
> > > + The number of \field{stats}.
> > > +
> > > + \item [queue_num]
> > > + The number of the virtqueue to obtain the statistics.
> > > +
> > > + \item [type]
> > > + The type of the stats to be obtained.
> > > +
> > > +\end{description}
> > > +
> > > +Correspondence between the vq type, the stats type, the stats structure
> > > and the
> > > +required features.
> > > +\begin{tabular}{ |l|l|l|l| }
> > > + \hline
> > > + VQ Type & Stats Type & Stats
> > > Structure & Features \\ \hline
> > > +
> > > + controlq & VIRTIO_NET_STATS_TYPE_CVQ &
> > > virtio_net_stats_cvq & \\ \hline
> > > +
> > > + \multirow{4}*{receiveq} & VIRTIO_NET_STATS_TYPE_RX_BASIC &
> > > virtio_net_stats_rx_basic & \\ \cline{2-4}
> > > + & VIRTIO_NET_STATS_TYPE_RX_CSUM &
> > > virtio_net_stats_rx_csum & VIRTIO_NET_F_GUEST_CSUM \\ \cline{2-4}
> > > + & VIRTIO_NET_STATS_TYPE_RX_GSO &
> > > virtio_net_stats_rx_gso & VIRTIO_NET_F_GUEST_TSO4 or\newline
> > > +
> > > VIRTIO_NET_F_GUEST_TSO6 or\newline
> > > +
> > > VIRTIO_NET_F_GUEST_UFO \\ \cline{2-4}
> > > + & VIRTIO_NET_STATS_TYPE_RX_RESET &
> > > virtio_net_stats_rx_reset & VIRTIO_F_RING_RESET \\ \hline
> > > +
> > > + \multirow{4}*{transmitq} & VIRTIO_NET_STATS_TYPE_TX_BASIC &
> > > virtio_net_stats_tx_basic & \\ \cline{2-4}
> > > + & VIRTIO_NET_STATS_TYPE_TX_CSUM &
> > > virtio_net_stats_tx_csum & VIRTIO_NET_F_CSUM \\ \cline{2-4}
> > > + & VIRTIO_NET_STATS_TYPE_TX_GSO &
> > > virtio_net_stats_tx_gso & VIRTIO_NET_F_HOST_TSO4 or\newline
> > > +
> > > VIRTIO_NET_F_HOST_TSO6 or\newline
> > > +
> > > VIRTIO_NET_F_HOST_USO or\newline
> > > +
> > > VIRTIO_NET_F_HOST_UFO \\ \cline{2-4}
> > > + & VIRTIO_NET_STATS_TYPE_TX_RESET &
> > > virtio_net_stats_tx_reset & VIRTIO_F_RING_RESET \\
> > > + \hline
> > > +\end{tabular}
> > > +
> > > +
> > > +\subparagraph{Controlq Stats}\label{sec:Device Types / Network Device /
> > > Device Operation / Control Virtqueue / Device Stats / Controlq Stats}
> > > +
> > > +The structure corresponding to the controlq stats is
> > > virtio_net_stats_cvq.
> > > +
> > > +\begin{description}
> > > + \item [command_num]
> > > + The number of commands, including the current command.
> > > +
> > > + \item [ok_num]
> > > + The number of commands (including the current command) where the
> > > ack was VIRTIO_NET_OK.
> > > +\end{description}
> > > +
> > > +
> > > +\subparagraph{Receiveq Basic Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Receiveq
> > > Basic Stats}
> > > +
> > > +The structure corresponding to the receiveq basic stats is
> > > virtio_net_stats_rx_basic.
> > > +
> > > +Receiveq basic stats doesn't need any features, as long as the device
> > > supports
> > > +VIRTIO_NET_F_CTRL_STATS. The following are the receiveq basic stats.
> > > +
> > > +\begin{description}
> > > + \item [rx_packets]
> > > + The number of packets received by device (not the packets passed
> > > to the
> > > + guest), including the dropped packets by device.
> > > +
> > > + \item [rx_bytes]
> > > + The number of bytes received by device (not the packets passed
> > > to the
> > > + guest), including the dropped packets by device.
> > > +
> > > + \item [rx_notification]
> > > + The number of driver notifications.
> > > +
> > > + \item [rx_interrupt]
> > > + The number of device interrupts.
> > > +
> > > + \item [rx_drop]
> > > + The number of packets dropped by the receiveq. Contains all
> > > kinds of
> > > + packet drop.
> > > +
> > > + \item [rx_drop_overruns]
> > > + The number of packets dropped by the receiveq when no more
> > > descriptors
> > > + were available.
> > > +
> > > +\end{description}
> > > +
> > > +\subparagraph{Transmitq Basic Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Transmitq
> > > Basic Stats}
> > > +
> > > +The structure corresponding to the transmitq basic stats is
> > > virtio_net_stats_tx_basic.
> > > +
> > > +Transmitq basic stats doesn't need any features, as long as the device
> > > supports
> > > +VIRTIO_NET_F_CTRL_STATS. The following are the transmitq basic stats.
> > > +
> > > +\begin{description}
> > > + \item [tx_packets]
> > > + The number of packets sent by device (not the packets got from
> > > the
> > > + guest), excluding the dropped packets by device.
> > > +
> > > + \item [tx_bytes]
> > > + The number of bytes sent by device (not the packets got from the
> > > + guest), excluding the dropped packets by device.
> > > +
> > > + \item [tx_notification]
> > > + The number of driver notifications.
> > > +
> > > + \item [tx_interrupt]
> > > + The number of device interrupts.
> > > +
> > > + \item [tx_drop]
> > > + The number of packets dropped by the transmitq. Contains all
> > > kinds of
> > > + packet drop.
> > > +
> > > + \item [tx_drop_malformed]
> > > + The number of packets dropped when the descriptor is in an error
> > > state.
> > > + For example, the buffer is too short.
> > > +
> > > +\end{description}
> > > +
> > > +\subparagraph{Receiveq CSUM Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Receiveq
> > > CSUM Stats}
> > > +
> > > +The structure corresponding to the receiveq csum stats is
> > > virtio_net_stats_rx_csum.
> > > +
> > > +Only after the VIRTIO_NET_F_GUEST_CSUM negotiation is successful, the
> > > receiveq
> > > +csum stats can be obtained.
> > > +
> > > +The following are the receiveq csum stats:
> > > +
> > > +\begin{description}
> > > + \item [rx_csum_valid]
> > > + The number of packets with VIRTIO_NET_HDR_F_DATA_VALID.
> > > +
> > > + \item [rx_needs_csum]
> > > + The number of packets with VIRTIO_NET_HDR_F_NEEDS_CSUM.
> > > +
> > > + \item [rx_csum_bad]
> > > + The number of packets with abnormal csum.
> > > +
> > > + \item [rx_csum_none]
> > > + The number of packets without hardware csum. The packet here
> > > refers to
> > > + the non-TCP/UDP packet that the backend cannot recognize.
> > > +
> > > +\end{description}
> > > +
> > > +\subparagraph{Transmitq CSUM Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Transmitq
> > > CSUM Stats}
> > > +
> > > +The structure corresponding to the transmitq csum stats is
> > > virtio_net_stats_tx_csum.
> > > +
> > > +Only after the VIRTIO_NET_F_CSUM negotiation is successful, the
> > > transmitq csum
> > > +stats can be obtained.
> > > +
> > > +The following are the transmitq csum stats:
> > > +
> > > +\begin{description}
> > > + \item [tx_csum_none]
> > > + The number of packets that didn't require hardware csum.
> > > +
> > > + \item [tx_needs_csum]
> > > + The number of packets that required hardware csum.
> > > +
> > > +\end{description}
> > > +
> > > +\subparagraph{Receiveq GSO Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Receiveq
> > > GSO Stats}
> > > +
> > > +The structure corresponding to the receiveq gso stats is
> > > virtio_net_stats_rx_gso.
> > > +
> > > +If one of the VIRTIO_NET_F_GUEST_TSO4, TSO6, or UFO options have
> > > +been negotiated, the receiveq gso stats can be obtained.
> > > +
> > > +Rx gso packets refer to packets passed by the device to the driver where
> > > +\field{gso_type} is not VIRTIO_NET_HDR_GSO_NONE.
> > > +
> > > +\begin{description}
> > > + \item [rx_gso_packets]
> > > + The number of the rx gso packets.
> > > +
> > > + \item [rx_gso_bytes]
> > > + The number of bytes(excluding the virtio net header) of the rx
> > > gso packets.
> > > +
> > > + \item [rx_gso_packets_coalesced]
> > > + The number of the rx gso packages generated by coalescing.
> > > +
> > > + \item [rx_gso_bytes_coalesced]
> > > + The number of bytes(excluding the virtio net header) of the rx
> > > gso packets generated by coalescing.
> > > +
> > > + \item [rx_gso_segments]
> > > + The number of coalesced segments.
> > > +
> > > + \item [rx_gso_segments_bytes]
> > > + The number of bytes of coalesced segments.
> > > +
> > > +\end{description}
> > > +
> > > +\subparagraph{Transmitq GSO Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Transmitq
> > > GSO Stats}
> > > +
> > > +The structure corresponding to the transmitq gso stats is
> > > virtio_net_stats_tx_gso.
> > > +
> > > +If one of the VIRTIO_NET_F_HOST_TSO4, TSO6, USO or UFO options have
> > > +been negotiated, the transmitq gso stats can be obtained.
> > > +
> > > +Tx gso packets refer to packets passed by the driver to the device where
> > > +\field{gso_type} is not VIRTIO_NET_HDR_GSO_NONE.
> > > +
> > > +\begin{description}
> > > + \item [tx_gso_packets]
> > > + The number of the tx gso packets.
> > > +
> > > + \item [tx_gso_bytes]
> > > + The number of bytes(excluding the virtio net header) of the tx
> > > gso packets.
> > > +
> > > + \item [tx_gso_packets_split]
> > > + The number of the tx gso packets that been split.
> > > +
> > > + \item [tx_gso_bytes_split]
> > > + The number of bytes(excluding the virtio net header) of the tx
> > > gso packets that been split.
> > > +
> > > + \item [tx_gso_segments]
> > > + The number of segments split from the gso package.
> > > +
> > > + \item [tx_gso_segments_bytes]
> > > + The number of bytes(excluding the virtio net header) of segments
> > > split from the gso package.
> > > +\end{description}
> > > +
> > > +\subparagraph{Receiveq Reset Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Receiveq
> > > Reset Stats}
> > > +
> > > +The structure corresponding to the receiveq reset stats is
> > > virtio_net_stats_rx_reset.
> > > +
> > > +Only when VIRTIO_F_RING_RESET is successfully negotiated, the receiveq
> > > reset stats
> > > +can be obtained.
> > > +
> > > +See \ref{sec:Basic Facilities of a Virtio Device / Virtqueues /
> > > Virtqueue Reset}
> > > +for more about \field{rx_reset}.
> > > +
> > > +\begin{description}
> > > + \item [rx_reset]
> > > + The number of receiveq resets.
> > > +\end{description}
> > > +
> > > +\subparagraph{Transmitq Reset Stats}\label{sec:Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats / Transmitq
> > > Reset Stats}
> > > +
> > > +The structure corresponding to the transmitq reset stats is
> > > virtio_net_stats_tx_reset.
> > > +
> > > +Only when VIRTIO_F_RING_RESET is successfully negotiated, the transmitq
> > > reset stats
> > > +can be obtained.
> > > +
> > > +See \ref{sec:Basic Facilities of a Virtio Device / Virtqueues /
> > > Virtqueue Reset}
> > > +for more about \field{tx_reset}.
> > > +
> > > +\begin{description}
> > > + \item [tx_reset]
> > > + The number of transmitq resets.
> > > +\end{description}
> > > +
> > > +\devicenormative{\subparagraph}{Device Stats}{Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats}
> > > +
> > > +If virtio_net_ctrl_queue_stats is incorrect (such as the following), the
> > > device
> > > +MUST set \field{ack} to VIRTIO_NET_ERR. Even if there is only one error,
> > > +the device MUST abort the entire command.
> > > +\begin{itemize}
> > > + \item \field{queue_num} exceeds the queue range.
> > > + \item \field{type} is not a known value.
> > > + \item The type of vq does not match \field{type}. E.g. the driver
> > > tries to query
> > > + RX stats through a TX index.
> > > + \item The feature corresponding to the specified \field{type} was
> > > not successfully
> > > + negotiated.
> > > + \item The size of the buffer allocated by the driver for
> > > \field{command-specific-data-reply}
> > > + is less than the total size of the stats specialed by
> > > + \field{virtio_net_ctrl_queue_stats}.
> > > +\end{itemize}
> > > +
> > > +The device MUST write the requested stats structures in
> > > +\field{command-specific-data-reply} in the order specified by the
> > > structure
> > > +virtio_net_ctrl_queue_stats.
> > > +
> > > +\drivernormative{\subparagraph}{Device Stats}{Device Types / Network
> > > Device / Device Operation / Control Virtqueue / Device Stats}
> > > +
> > > +When a driver tries to obtain a certain stats, it MUST confirm that the
> > > relevant
> > > +feature negotiation is successful.
> > > +
> > > +\field{type} in struct virtio_net_ctrl_queue_stats MUST correspond to
> > > the vq
> > > +specified by \field{queue_num}.
> > > +
> > > +The \field{command-specific-data-reply} buffer allocated by the driver
> > > MUST be
> > > +able to hold all the stats specified by virtio_net_ctrl_queue_stats.
> > > +
> > > +When the driver reads the response, it MUST read
> > > +\field{command-specific-data-reply} one by one based on the \field{type}.
> > >
> > > \subsubsection{Legacy Interface: Framing Requirements}\label{sec:Device
> > > Types / Network Device / Legacy Interface: Framing Requirements}
> > > --
> > > 2.31.0
> >
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