RE: proposal: use admin command (and aq) of the device to query config space

[Parav Pandit <parav@nvidia.com>]

> From: Zhu, Lingshan <lingshan.zhu@intel.com>
> Sent: Wednesday, August 2, 2023 2:15 PM
> Rebasing "transport vq" on admin vq is still in my pipeline, I am currently
> working on a patch series implementing virtio pci live migration in the
> spec(carry on Jason and Eugenio's work).
> I will post it next week and back to transport vq task then.
> 
Awesome and interesting to us as well.
I have draft for member device migration admin commands.
I guess yours will hit the mailing list first, so we can converge on your series.

> For SIOV, I have implemented the interfaces for querying the configurations, for
> example:
> 1) Access config space:
> 
> 247 +\begin{lstlisting}
> 248 +#define VIRTIO_TRANSPTQ_CTRL_CONFIGÂÂÂ 6
> 249 +Â #define VIRTIO_TRANSPTQ_CTRL_CONFIG_GETÂÂÂ 0
> 250 +Â #define VIRTIO_TRANSPTQ_CTRL_CONFIG_SETÂÂÂ 1
> 251 +
> 252 +struct virtio_transportq_ctrl_dev_config_get {
> 253 +ÂÂÂÂÂÂ u32 offset;
> 254 +ÂÂÂÂÂÂ u32 size;
> 255 +};
> 256 +
> 257 +struct virtio_transportq_ctrl_dev_config_set {
> 258 +ÂÂÂÂÂÂ u32 offset;
> 259 +ÂÂÂÂÂÂ u32 size;
> 260 +ÂÂÂÂÂÂ u8Â data[];
> 261 +};
> 262 +\end{lstlisting}
> 
> I think we can re-use the GET command for SR-IOV, I am afraid SET would be a
> side-channel attacking surface for SR-IOV.
> 
Get and set both should be inband for PF, VF, SIOV.
I donât see any need to diverge and create any weird combinations differently for 3 different device types.

> 2) a specific config, e.g., features:
> 
> 142 +The features negotiation of managed devices is done by the
> 143 +following commands:
> 144 +
> 145 +\begin{lstlisting}
> 146 +#define VIRTIO_TRANSPTQ_CTRL_FEATÂÂ 3
> 147 + #define VIRTIO_TRANSPTQ_CTRL_FEAT_DEVICE_GETÂÂÂÂÂÂÂ 0
> 148 + #define VIRTIO_TRANSPTQ_CTRL_FEAT_DRIVER_SETÂÂÂÂÂÂÂ 1
> 149 + #define VIRTIO_TRANSPTQ_CTRL_FEAT_DRIVER_GETÂÂÂÂÂÂÂ 2
> 150 +
> 151 +struct virtio_transportq_ctrl_dev_features {
> 152 +ÂÂÂÂÂÂÂ u32 features_len;
> 153 +ÂÂÂÂÂÂÂ u32 features[features_len];
> 154 +};
> 155 +\end{lstlisting}
> 
> still can re-use the GET commands.
> 
> Thanks
> Zhu Lingshan
> >