Re: [dpdk-dev] [PATCH] net/ifc: do not notify before HW ready

["Wang, Xiao W" <xiao.w.wang@intel.com>]

Hi Xiaolong,

> -----Original Message-----
> From: Ye, Xiaolong
> Sent: Thursday, September 13, 2018 8:55 PM
> To: Wang, Xiao W <xiao.w.wang@intel.com>
> Cc: Bie, Tiwei <tiwei.bie@intel.com>; dev@dpdk.org
> Subject: Re: [PATCH] net/ifc: do not notify before HW ready
> 
> Hi, Xiao
> 
> On 09/10, Xiao Wang wrote:
> >Fixes: a3f8150eac6d ("net/ifcvf: add ifcvf vDPA driver")
> 
> Could you help describe what problem is without this fix in commit log?

Generally a driver should finish all the device configurations first then notify the HW for data processing.
Without this fix, the potential problems are:
1. If the device is not clearly reset by the previous driver and holds some invalid ring addr, and the vDPA relay thread kicks it, a bad DMA request may happen.
2. The notify_addr which is used by the relay thread is set in the vdpa_ifcvf_start function. If there's really a kick relay before vdpa_ifcvf_start finishes, a null addr is accessed.

Would add the description in the commit log in v2.

Thanks for the comment,
Xiao
> 
> Thanks,
> Xiaolong
> >
> >Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
> >---
> > drivers/net/ifc/ifcvf_vdpa.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
> >
> >diff --git a/drivers/net/ifc/ifcvf_vdpa.c b/drivers/net/ifc/ifcvf_vdpa.c
> >index 3c5430dc0..7d3085d8d 100644
> >--- a/drivers/net/ifc/ifcvf_vdpa.c
> >+++ b/drivers/net/ifc/ifcvf_vdpa.c
> >@@ -503,11 +503,11 @@ update_datapath(struct ifcvf_internal *internal)
> > 		if (ret)
> > 			goto err;
> >
> >-		ret = setup_notify_relay(internal);
> >+		ret = vdpa_ifcvf_start(internal);
> > 		if (ret)
> > 			goto err;
> >
> >-		ret = vdpa_ifcvf_start(internal);
> >+		ret = setup_notify_relay(internal);
> > 		if (ret)
> > 			goto err;
> >
> >@@ -515,12 +515,12 @@ update_datapath(struct ifcvf_internal *internal)
> > 	} else if (rte_atomic32_read(&internal->running) &&
> > 		   (!rte_atomic32_read(&internal->started) ||
> > 		    !rte_atomic32_read(&internal->dev_attached))) {
> >-		vdpa_ifcvf_stop(internal);
> >-
> > 		ret = unset_notify_relay(internal);
> > 		if (ret)
> > 			goto err;
> >
> >+		vdpa_ifcvf_stop(internal);
> >+
> > 		ret = vdpa_disable_vfio_intr(internal);
> > 		if (ret)
> > 			goto err;
> >--
> >2.15.1
> >