Re: [virtio-dev] [RFC PATCH 5/5] virtio-pci: implement VIRTIO_F_QUEUE_STATE

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Tue, Aug 15, 2023 at 03:29:04AM +0800, Zhu Lingshan wrote:
> This patch adds two new le16 fields to common configruation structure
> to support VIRTIO_F_QUEUE_STATE in PCI tranport layer.
> 
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> ---
>  transport-pci.tex | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/transport-pci.tex b/transport-pci.tex
> index a5c6719..d9bccb0 100644
> --- a/transport-pci.tex
> +++ b/transport-pci.tex
> @@ -321,6 +321,8 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
>          le64 queue_device;              /* read-write */
>          le16 queue_notif_config_data;   /* read-only for driver */
>          le16 queue_reset;               /* read-write */
> +        le16 queue_avail_state;         /* read-write */
> +        le16 queue_used_state;          /* read-write */
>  
>          /* About the administration virtqueue. */
>          le16 admin_queue_index;         /* read-only for driver */

This is an incompatible change to the register layout. Please add new
registers at the end of struct virtio_pci_common_cfg so field offsets
don't change for existing drivers and devices.

> @@ -415,6 +417,16 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
>          This field exists only if VIRTIO_F_RING_RESET has been
>          negotiated. (see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}).
>  
> +\item[\field{queue_avail_state}]
> +        This field is vaild only if VIRTIO_F_QUEUE_STATE has been

"valid"

> +        negotiated. The driver sets and gets the available state of
> +        the virtqueue here (see \ref{sec:Virtqueues / Virtqueue State}).
> +
> +\item[\field{queue_used_state}]
> +        This field is vaild only if VIRTIO_F_QUEUE_STATE has been

"valid"

> +        negotiated. The driver sets and gets the used state of the
> +        virtqueue here (see \ref{sec:Virtqueues / Virtqueue State}).
> +
>  \item[\field{admin_queue_index}]
>          The device uses this to report the index of the first administration virtqueue.
>          This field is valid only if VIRTIO_F_ADMIN_VQ has been negotiated.
> @@ -488,6 +500,9 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
>  present either a value of 0 or a power of 2 in
>  \field{queue_size}.
>  
> +If VIRTIO_F_QUEUE_STATE has not been negotiated, the device MUST ignore
> +any accesses against \field{queue_avail_state} and \field{queue_used_state}.

"accesses to"

> +
>  If VIRTIO_F_ADMIN_VQ has been negotiated, the value
>  \field{admin_queue_index} MUST be equal to, or bigger than
>  \field{num_queues}; also, \field{admin_queue_num} MUST be
> -- 
> 2.35.3
> 
> 
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