Re: [dpdk-dev] [PATCH v2 1/5] bus/fslmc: fix physical addressing check

[Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>]

On Fri, Oct 12, 2018 at 04:14:36PM +0530, Shreyansh Jain wrote:
> On Friday 12 October 2018 02:31 PM, Pavan Nikhilesh wrote:
> > Hi Shreyansh,
> >
> > On Tue, Oct 09, 2018 at 04:55:44PM +0530, Shreyansh Jain wrote:
> > > In case RTE_LIBRTE_DPAA2_USE_PHYS_IOVA is enabled, only supported
> > > class is RTE_IOVA_PA.
> > >
> > > Fixes: f7768afac101 ("bus/fslmc: support dynamic IOVA")
> > > Cc: hemant.agrawal@nxp.com
> > >
> > > Signed-off-by: Shreyansh Jain <shreyansh.jain@nxp.com>
> > > ---
> > >   drivers/bus/fslmc/fslmc_bus.c | 4 ++++
> > >   1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/bus/fslmc/fslmc_bus.c b/drivers/bus/fslmc/fslmc_bus.c
> > > index bfe81e236..a4f9a9eee 100644
> > > --- a/drivers/bus/fslmc/fslmc_bus.c
> > > +++ b/drivers/bus/fslmc/fslmc_bus.c
> > > @@ -491,6 +491,10 @@ rte_dpaa2_get_iommu_class(void)
> > >          bool is_vfio_noiommu_enabled = 1;
> > >          bool has_iova_va;
> > >
> > > +#ifdef RTE_LIBRTE_DPAA2_USE_PHYS_IOVA
> > > +       return RTE_IOVA_PA;
> > > +#endif
> > > +
> >
> > As, RTE_LIBRTE_DPAA2_USE_PHYS_IOVA is set to true by default[1] and fslmc bus
> > being always registered[2] irrespective of the underlying platform, the IOVA class
> > will be always returned as PA.
> > This will break multiple platforms as some work only when IOVA as VA. I think
> > you need to verify if the underlying platform is really FLMC similar to DPAA[3]
>
> Thats a good catch and bad patch from me :( - Thanks for review.
> I will do this now:
>
> ---->8---
> static enum rte_iova_mode
> rte_dpaa2_get_iommu_class(void)
> {
>         bool is_vfio_noiommu_enabled = 1;
>         bool has_iova_va;
>
> - #ifdef RTE_LIBRTE_DPAA2_USE_PHYS_IOVA
> -        return RTE_IOVA_PA;
> - #endif
>
>         if (TAILQ_EMPTY(&rte_fslmc_bus.device_list))
>                 return RTE_IOVA_DC;
>
> + #ifdef RTE_LIBRTE_DPAA2_USE_PHYS_IOVA
> +        return RTE_IOVA_PA;
> + #endif
> ---->8---
>
> In this case, in case no FSLMC device is detected (which would be cases
> you are referring to), DC would be returned.
>
> There is no other explicit way for me to check the PA/VA combination on
> the DPAA2 bus. Even for the DPAA function [3]that you have mentioned,
> that is not actually checking PA/VA applicability - it is just checking
> if we have DPAA enabled or not (complete bus).
>
> Is that OK?

Looks good to me :) cheers - Pavan.

>
> >
> > [1]
> > ->[master]ltp-pvn[dpdk] $ grep -nir "RTE_LIBRTE_DPAA2_USE_PHYS_IOVA" config/
> > config/meson.build:86:dpdk_conf.set('RTE_LIBRTE_DPAA2_USE_PHYS_IOVA', true)
> > config/common_base:218:CONFIG_RTE_LIBRTE_DPAA2_USE_PHYS_IOVA=y
> >
> > [2]
> > config/common_linuxapp:45:CONFIG_RTE_LIBRTE_FSLMC_BUS=y
> >
> > [3]
> >       static enum rte_iova_mode
> >       rte_dpaa_get_iommu_class(void)
> >       {
> >               if ((access(DPAA_DEV_PATH1, F_OK) != 0) &&
> >                               (access(DPAA_DEV_PATH2, F_OK) != 0)) {
> >                       return RTE_IOVA_DC;
> >               }
> >               return RTE_IOVA_PA;
> >       }
> >
> >
> > >          if (TAILQ_EMPTY(&rte_fslmc_bus.device_list))
> > >                  return RTE_IOVA_DC;
> > >
>