Re: [dpdk-dev] [PATCH] doc: Malicious Driver Detection not supported by ixgbe

["Lu, Wenzhuo" <wenzhuo.lu@intel.com>]

Hi Stephen,


> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Thursday, February 25, 2016 1:04 AM
> To: Lu, Wenzhuo
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] doc: Malicious Driver Detection not supported
> by ixgbe
> 
> On Wed, 24 Feb 2016 13:33:04 +0800
> Wenzhuo Lu <wenzhuo.lu@intel.com> wrote:
> 
> > +  On Intel x550 series NICs, HW supports a feature called MDD
> > + (Malcicious  Driver Detection).
> > +  MDD is used to check the behavior of the VF driver. It means when
> > + transmitting  packets, the VF must use the advanced context descriptor and
> set it correctly.
> > +  And VF must set the CC (Check Context) bit either.
> 
> This is hard sentence to read, why not reword as:
> 
> The Intel x550 series NIC's support1 a feature called MDD (Malcicious Driver
> Detection) which checks the behavior of the VF driver.
> If this feature is enabled, the VF must use the advanced context descriptor
> correctly and set the CC (Check Context) bit.
Thanks for the suggestion. I'll try to make it better :)

> 
> 
> > +  DPDK PF doesn't support MDD. We may hit problem in this scenario
> > + kernel PF +  DPDK VF. If user enables MDD in kernel PF, DPDK VF will
> > + not work. Because  kernel PF thinks the VF is malicious. But
> > + actually it's not. The only reason  is the VF doesn't act as MDD required.
> > +  There's significant performance impact to support MDD. DPDK should
> > + check if  the advanced context descriptor should be set and set it.
> > + And DPDK has to ask  the info about the header length from the upper
> > + layer, because parsing the  packet itself is not acceptale. So, it's too
> expensive to support MDD.
> > +  When using kernel PF + DPDK VF on x550, please make sure using the
> > + kernel  driver that disables MDD or can disable MDD. (Some kernel
> > + driver can use  this CLI 'insmod ixgbe.ko MDD=0,0' to disable MDD.
> > + Some kernel driver disable  it by default.)
> > +