Re: [PATCH v3 04/10] net/ice/base: set speculative execution barrier

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, May 28, 2025 at 02:07:25PM +0100, Bruce Richardson wrote:
> On Tue, May 27, 2025 at 01:17:23PM +0000, Dhanya Pillai wrote:
> > From: Lukasz Krakowiak <lukaszx.krakowiak@intel.com>
> > 
> > Fix issues related to SPECULATIVE_EXECUTION_DATA_LEAK.
> > This changes set speculative execution barrier to functions:
> > 
> > * ice_sched_add_vsi_child_nodes,
> > * ice_sched_add_vsi_support_nodes,
> > * ice_sched_move_vsi_to_agg,
> > * ice_prof_has_mask_idx,
> > * ice_alloc_prof_mask.
> > 
> > Also, Added memfence definitions.
> > 
> > Signed-off-by: Lukasz Krakowiak <lukaszx.krakowiak@intel.com>
> > Signed-off-by: Dhanya Pillai <dhanya.r.pillai@intel.com>
> > ---
> >  drivers/net/intel/ice/base/ice_flex_pipe.c | 2 ++
> >  drivers/net/intel/ice/base/ice_osdep.h     | 6 ++++++
> >  drivers/net/intel/ice/base/ice_sched.c     | 3 +++
> >  3 files changed, 11 insertions(+)
> > 
> > diff --git a/drivers/net/intel/ice/base/ice_flex_pipe.c b/drivers/net/intel/ice/base/ice_flex_pipe.c
> > index 6dd5588f85..dc8c92e203 100644
> > --- a/drivers/net/intel/ice/base/ice_flex_pipe.c
> > +++ b/drivers/net/intel/ice/base/ice_flex_pipe.c
> > @@ -1280,6 +1280,7 @@ ice_prof_has_mask_idx(struct ice_hw *hw, enum ice_block blk, u8 prof, u16 idx,
> >  			if (hw->blk[blk].masks.masks[i].in_use &&
> >  			    hw->blk[blk].masks.masks[i].idx == idx) {
> >  				found = true;
> > +				ice_memfence_read();
> >  				if (hw->blk[blk].masks.masks[i].mask == mask)
> >  					match = true;
> >  				break;
> > @@ -1648,6 +1649,7 @@ ice_alloc_prof_mask(struct ice_hw *hw, enum ice_block blk, u16 idx, u16 mask,
> >  			/* if mask is in use and it exactly duplicates the
> >  			 * desired mask and index, then in can be reused
> >  			 */
> > +			ice_memfence_read();
> >  			if (hw->blk[blk].masks.masks[i].mask == mask &&
> >  			    hw->blk[blk].masks.masks[i].idx == idx) {
> >  				found_copy = true;
> > diff --git a/drivers/net/intel/ice/base/ice_osdep.h b/drivers/net/intel/ice/base/ice_osdep.h
> > index ad6cde9896..7588ad3dbc 100644
> > --- a/drivers/net/intel/ice/base/ice_osdep.h
> > +++ b/drivers/net/intel/ice/base/ice_osdep.h
> > @@ -203,6 +203,12 @@ struct __rte_packed_begin ice_virt_mem {
> >  #define ice_memset(a, b, c, d) memset((a), (b), (c))
> >  #define ice_memcpy(a, b, c, d) rte_memcpy((a), (b), (c))
> >  
> > +/* Memory fence barrier */
> > +#define ice_memfence_read()
> > +#define ice_memfence_read_write()
> > +#define ice_memfence_write()
> > +
> 
> I suspect rather than removing this, they would be better defined as
> rte_smp_* barriers. As in:
> 
> #define ice_memfence_read() rte_smp_rmb()
> 
Correcting my own suggestion - since this is a NIC driver, we probably want
to use rte_io_* barriers, not the rte_smp_* ones.

/Bruce