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

[Shreyansh Jain <shreyansh.jain@nxp.com>]

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?

> 
> [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;
>>