Re: [EXT] Re: [net PATCH 1/7] octeontx2-af: Secure APR table update with the lock

[Leon Romanovsky]

On Thu, Mar 30, 2023 at 06:56:54AM +0000, Geethasowjanya Akula wrote:
> 
> >-----Original Message-----
> >From: Leon Romanovsky <leon@xxxxxxxxxx> 
> >Sent: Thursday, March 30, 2023 11:26 AM
> >To: Sai Krishna Gajula <saikrishnag@xxxxxxxxxxx>
> >Cc: davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Sunil Kovvuri Goutham <sgoutham@xxxxxxxxxxx>; >richardcochran@xxxxxxxxx; Geethasowjanya Akula <gakula@xxxxxxxxxxx>
> >Subject: [EXT] Re: [net PATCH 1/7] octeontx2-af: Secure APR table update with the lock
> 
> >External Email
> 
> >----------------------------------------------------------------------
> >On Wed, Mar 29, 2023 at 10:36:13PM +0530, Sai Krishna wrote:
> >> From: Geetha sowjanya <gakula@xxxxxxxxxxx>
> >> 
> >> APR table contains the lmtst base address of PF/VFs.
> >> These entries are updated by the PF/VF during the device probe. Due to 
> >> race condition while updating the entries are getting corrupted. Hence 
> >> secure the APR table update with the lock.
> 
> >However, I don't see rsrc_lock in probe path.
> >otx2_probe()
> >-> cn10k_lmtst_init()
> > -> lmt_base/lmstst is updated with and without mbox.lock.
> 
> >Where did you take rsrc_lock in probe flow?
> 
> rsrc_lock is initialized in AF driver. PF/VF driver in cn10k_lmtst_init() send a mbox request to AF to update the lmtst table. 
> mbox handler in AF takes rsrc_lock to update lmtst table.

Can you please present the stack trace of such flow? What are the actual variables/struct rsrc_lock
is protecting?

Thanks

> 
> Thanks,
> Geetha.
> 
> >Thanks
> 
> >> 
> >> Fixes: 893ae97214c3 ("octeontx2-af: cn10k: Support configurable LMTST 
> >> regions")
> >> Signed-off-by: Geetha sowjanya <gakula@xxxxxxxxxxx>
> >> Signed-off-by: Sunil Kovvuri Goutham <sgoutham@xxxxxxxxxxx>
> >> Signed-off-by: Sai Krishna <saikrishnag@xxxxxxxxxxx>
> >> ---
> >>  drivers/net/ethernet/marvell/octeontx2/af/rvu_cn10k.c | 8 +++++---
> >>  1 file changed, 5 insertions(+), 3 deletions(-)
> >> 
> >> diff --git a/drivers/net/ethernet/marvell/octeontx2/af/rvu_cn10k.c 
> >> b/drivers/net/ethernet/marvell/octeontx2/af/rvu_cn10k.c
> >> index 4ad9ff025c96..8530250f6fba 100644
> >> --- a/drivers/net/ethernet/marvell/octeontx2/af/rvu_cn10k.c
> >> +++ b/drivers/net/ethernet/marvell/octeontx2/af/rvu_cn10k.c
> >> @@ -142,16 +142,17 @@ int rvu_mbox_handler_lmtst_tbl_setup(struct rvu *rvu,
> >>  	 * region, if so, convert that IOVA to physical address and
> >>  	 * populate LMT table with that address
> >>  	 */
> >> +	mutex_lock(&rvu->rsrc_lock);
> >>  	if (req->use_local_lmt_region) {
> >>  		err = rvu_get_lmtaddr(rvu, req->hdr.pcifunc,
> >>  				      req->lmt_iova, &lmt_addr);
> >>  		if (err < 0)
> >> -			return err;
> >> +			goto error;
> >>  
> >>  		/* Update the lmt addr for this PFFUNC in the LMT table */
> >>  		err = rvu_update_lmtaddr(rvu, req->hdr.pcifunc, lmt_addr);
> >>  		if (err)
> >> -			return err;
> >> +			goto error;
> >>  	}
> >>  
> >>  	/* Reconfiguring lmtst map table in lmt region shared mode i.e. make 
> >> @@ -181,7 +182,7 @@ int rvu_mbox_handler_lmtst_tbl_setup(struct rvu *rvu,
> >>  		 */
> >>  		err = rvu_update_lmtaddr(rvu, req->hdr.pcifunc, val);
> >>  		if (err)
> >> -			return err;
> >> +			goto error;
> >>  	}
> >>  
> >>  	/* This mailbox can also be used to update word1 of 
> >> APR_LMT_MAP_ENTRY_S @@ -230,6 +231,7 @@ int rvu_mbox_handler_lmtst_tbl_setup(struct rvu *rvu,
> >>  	}
> >>  
> >>  error:
> >> +	mutex_unlock(&rvu->rsrc_lock);
> >>  	return err;
> >>  }
> >>  
> >> --
> >> 2.25.1
> >>