Re: [PATCH V2 6/6] virtio-pci: implement dirty page tracking

["Zhu, Lingshan" <lingshan.zhu@intel.com>]

On 11/3/2023 6:46 PM, Michael S. Tsirkin wrote:
> On Fri, Nov 03, 2023 at 06:34:37PM +0800, Zhu Lingshan wrote:
> > +\begin{lstlisting}
> > +struct virtio_pci_dity_page_track {
> > +        u8 enable;               /* Read-Write */
> > +        u8 gra_power;            /* Read-Write */
> > +        u8 reserved[2];
> > +        le32 {
> > +            pasid: 20;           /* Read-Write */
> > +            reserved: 12;
> > +        };
> > +        le64 bitmap_addr;        /* Read-Write */
> > +        le64 bitmap_length;      /* Read-Write */
> > +};
> > +\end{lstlisting}
> Okay, so it's a simple mailbox in config space.  Which by itself is
> probably a very reasonable idea - more or less what I suggested.
> However, using such a generic facility just for the dirty bitmap seems
> too limited.  Please make it accept arbitrary commands. Reusing admin
> command structure with a special "device itself" group sounds like one
> way to do it.
processing admin cmds in a cap may be too complex and overkill.
we need to handle variable length of cmds, handle async returned 
results, and so on.

This struct seems easy and simple. And shall we use platform facilities 
like vt-d
to track dirty pages?
>