Re: [PATCH] crypto: iaa: Fix some errors in IAA documentation

[Tom Zanussi <tom.zanussi@linux.intel.com>]

Hi Jerry,

On Mon, 2024-03-18 at 00:49 -0700, Jerry Snitselaar wrote:
> On Sun, Mar 17, 2024 at 11:44:21PM -0700, Jerry Snitselaar wrote:
> > This cleans up the following issues I ran into when trying to use
> > the
> > scripts and commands in the iaa-crypto.rst document.
> > 
> > - Fix incorrect arguments being passed to accel-config
> >   config-wq.
> >     - Replace --device_name with --driver-name.
> >     - Replace --driver_name with --driver-name.
> >     - Replace --size with --wq-size.
> >     - Add missing --priority argument.
> > - Add missing accel-config config-engine command after the
> >   config-wq commands.
> > - Fix wq name passed to accel-config config-wq.
> > - Add rmmod/modprobe of iaa_crypto to script that disables,
> >   then enables all devices and workqueues to avoid enable-wq
> >   failing with -EEXIST when trying to register to compression
> >   algorithm.
> > - Fix device name in cases where iaa was used instead of iax.
> > 
> > Cc: Tom Zanussi <tom.zanussi@linux.intel.com>
> > Cc: Jonathan Corbet <corbet@lwn.net>
> > Cc: linux-crypto@vger.kernel.org
> > Cc: linux-doc@vger.kernel.org
> > Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
> > ---
> >  .../driver-api/crypto/iaa/iaa-crypto.rst      | 22 ++++++++++++++-
> > ----
> >  1 file changed, 16 insertions(+), 6 deletions(-)
> > 
> > diff --git a/Documentation/driver-api/crypto/iaa/iaa-crypto.rst
> > b/Documentation/driver-api/crypto/iaa/iaa-crypto.rst
> > index de587cf9cbed..330d35df5f16 100644
> > --- a/Documentation/driver-api/crypto/iaa/iaa-crypto.rst
> > +++ b/Documentation/driver-api/crypto/iaa/iaa-crypto.rst
> > @@ -179,7 +179,9 @@ has the old 'iax' device naming in place) ::
> >  
> >    # configure wq1.0
> >  
> > -  accel-config config-wq --group-id=0 --mode=dedicated --
> > type=kernel --name="iaa_crypto" --device_name="crypto" iax1/wq1.0
> > +  accel-config config-wq --group-id=0 --mode=dedicated --
> > type=kernel --priority=10 --name="iaa_crypto" --driver-
> > name="crypto" iax1/wq1.0
> > +
> > +  accel-config config-engine iax1/engine1.0 --group-id=0
> >  
> >    # enable IAA device iax1
> >  
> > @@ -536,12 +538,20 @@ The below script automatically does that::
> >  
> >    echo "End Disable IAA"
> >  
> > +  echo "Reload iaa_crypto module"
> > +
> > +  rmmod iaa_crypto
> > +  modprobe iaa_crypto
> > +
> > +  echo "End Reload iaa_crypto module"
> > +
> >    #
> >    # configure iaa wqs and devices
> >    #
> >    echo "Configure IAA"
> >    for ((i = 1; i < ${num_iaa} * 2; i += 2)); do
> > -      accel-config config-wq --group-id=0 --mode=dedicated --
> > size=128 --priority=10 --type=kernel --name="iaa_crypto" --
> > driver_name="crypto" iax${i}/wq${i}
> > +      accel-config config-wq --group-id=0 --mode=dedicated --wq-
> > size=128 --priority=10 --type=kernel --name="iaa_crypto" --driver-
> > name="crypto" iax${i}/wq${i}.0
> > +      accel-config config-engine iax${i}/engine${i}.0 --group-id=0
> >    done
> >  
> >    echo "End Configure IAA"
> > @@ -552,10 +562,10 @@ The below script automatically does that::
> >    echo "Enable IAA"
> >  
> >    for ((i = 1; i < ${num_iaa} * 2; i += 2)); do
> > -      echo enable iaa iaa${i}
> > -      accel-config enable-device iaa${i}
> > -      echo enable wq iaa${i}/wq${i}.0
> > -      accel-config enable-wq iaa${i}/wq${i}.0
> > +      echo enable iaa iax${i}
> > +      accel-config enable-device iax${i}
> > +      echo enable wq iax${i}/wq${i}.0
> > +      accel-config enable-wq iax${i}/wq${i}.0
> >    done
> >  
> >    echo "End Enable IAA"
> > -- 
> > 2.41.0
> > 
> 
> In addition to the above, the sections related to the modes seem
> to be off to me.
> 
> Legacy mode in the Intel IOMMU context is when the IOMMU does not
> have
> scalable mode enabled. If you pass intel_iommu=off the Intel IOMMU
> will not be initialized, and I think that would correspond to the No
> IOMMU
> mode instead of Legacy mode. The other suggestion for Legacy mode of
> disabling VT-d in the BIOS would also be No IOMMU mode, but in
> addition to the dma remapping units being disabled it would disable
> interrupt remapping since the DMAR table would no longer be presented
> to the OS by the BIOS.
> 
> I think the modes should be:
> 
> Scalable mode: intel_iommu=on,sm_on
> Legacy mode: intel_iommu=on
> No IOMMU mode: intel_iommu=off (or VT-d disabled in BIOS)
> 

Yes, I think you're correct, those make more sense.

> Since Intel IOMMU and scabale mode have config options that allow
> them
> to be enabled by default, there are different parameter variations
> that would match the above cases. I don't know if they need to
> be detailed here, or if it would just make it more confusing.
> 

Personally, I think it would be useful to have them detailed and might
lessen confusion for people setting things up and/or debugging a setup.

Thanks,

Tom

> Regards,
> Jerry
>