Re: [PATCH vhost v4 02/15] vdpa: Add VHOST_BACKEND_F_CHANGEABLE_VQ_ADDR_IN_SUSPEND flag

Michael S. Tsirkin
2023-12-22T08:29:13Z

On Thu, Dec 21, 2023 at 03:07:22PM +0000, Dragos Tatulea wrote:
> > > > In that case you're right, we don't need feature flags. But I think it
> > > > would be great to also move the error return in case userspace tries
> > > > to modify vq parameters out of suspend state.
> > > >
> > > On the driver side or on the core side?
> > >
> >
> > Core side.
> >
> Checking my understanding: instead of the feature flags there would be a check
> (for .set_vq_addr and .set_vq_state) to return an error if they are called under
> DRIVER_OK and not suspended state?

Yea this looks much saner, if we start adding feature flags for
each OPERATION_X_LEGAL_IN_STATE_Y then we will end up with N^2
feature bits which is not reasonable.

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MST