Re: [RFC PATCH v3 12/15] hw/arm/smmuv3-accel: Introduce helpers to batch and issue cache invalidations

[Nicolin Chen <nicolinc@nvidia.com>]

On Mon, Sep 08, 2025 at 02:59:55AM -0700, Shameer Kolothum wrote:
> > -----Original Message-----
> > From: Eric Auger <eric.auger@redhat.com>
> > > +/*
> > > + * SMMUCommandBatch - batch of invalidation commands for accel
> > smmuv3
> > > + * @cmds: Pointer to list of commands
> > > + * @cons: Pointer to list of CONS corresponding to the commands
> > It is not totally clear to me how the list of "CONS" indexes is used. Is
> > it meant to store errors, how do you update cons index in case it starts
> > failing, ...
> 
> This is how I understand it,
> 
> The cons here is to store SMMUv3 queue cons corresponding to the cmd. And
> in case batched invalidation fails(iommufd_backend_invalidate_cache()), it will
> update the batch->ncmds with the index of the last failed command. The cons
> value at that index is then used to update the SMMUv3 cons index.

Yes. It is used to update the CONS index to the vSMMU CMDQ.

Nicolin