[dpdk-dev] [dpdk-stable] [PATCH v3 1/6] mem: add function for checking memsegs IOVAs addresses

[Alejandro Lucero]

On Tue, Jul 10, 2018 at 9:56 AM, Eelco Chaudron <echaudro at redhat.com> wrote:

>
>
> On 4 Jul 2018, at 14:53, Alejandro Lucero wrote:
>
> A device can suffer addressing limitations. This functions checks
>> memsegs have iovas within the supported range based on dma mask.
>>
>> PMD should use this during initialization if supported devices
>> suffer addressing limitations, returning an error if this function
>> returns memsegs out of range.
>>
>> Another potential usage is for emulated IOMMU hardware with addressing
>> limitations.
>>
>> Signed-off-by: Alejandro Lucero <alejandro.lucero at netronome.com>
>> Acked-by: Anatoly Burakov <anatoly.burakov at intel.com>
>> ---
>>  lib/librte_eal/common/eal_common_memory.c  | 33
>> ++++++++++++++++++++++++++++++
>>  lib/librte_eal/common/include/rte_memory.h |  3 +++
>>  lib/librte_eal/rte_eal_version.map         |  1 +
>>  3 files changed, 37 insertions(+)
>>
>> diff --git a/lib/librte_eal/common/eal_common_memory.c
>> b/lib/librte_eal/common/eal_common_memory.c
>> index fc6c44d..f5efebe 100644
>> --- a/lib/librte_eal/common/eal_common_memory.c
>> +++ b/lib/librte_eal/common/eal_common_memory.c
>> @@ -109,6 +109,39 @@
>>         }
>>  }
>>
>> +/* check memseg iovas are within the required range based on dma mask */
>> +int
>> +rte_eal_check_dma_mask(uint8_t maskbits)
>> +{
>> +
>> +       const struct rte_mem_config *mcfg;
>> +       uint64_t mask;
>> +       int i;
>> +
>>
>
> I think we should add some sanity check to the input maskbits, i.e. [64,0)
> or [64, 32]? What would be a reasonable lower bound.
>
>
This is not a user's API, so any invocation will be reviewed, but I guess
adding a sanity check here does not harm.

Not sure about lower bound but upper should 64, although it does not make
sense but it is safe. Lower bound is not so problematic.


>
> +       /* create dma mask */
>> +       mask = ~((1ULL << maskbits) - 1);
>> +
>> +       /* get pointer to global configuration */
>> +       mcfg = rte_eal_get_configuration()->mem_config;
>> +
>> +       for (i = 0; i < RTE_MAX_MEMSEG; i++) {
>> +               if (mcfg->memseg[i].addr == NULL)
>> +                       break;
>> +
>> +               if (mcfg->memseg[i].iova & mask) {
>> +                       RTE_LOG(INFO, EAL,
>> +                               "memseg[%d] iova %"PRIx64" out of
>> range:\n",
>> +                               i, mcfg->memseg[i].iova);
>> +
>> +                       RTE_LOG(INFO, EAL, "\tusing dma mask %"PRIx64"\n",
>> +                               mask);
>> +                       return -1;
>> +               }
>> +       }
>> +
>> +       return 0;
>> +}
>> +
>>  /* return the number of memory channels */
>>  unsigned rte_memory_get_nchannel(void)
>>  {
>> diff --git a/lib/librte_eal/common/include/rte_memory.h
>> b/lib/librte_eal/common/include/rte_memory.h
>> index 80a8fc0..b2a0168 100644
>> --- a/lib/librte_eal/common/include/rte_memory.h
>> +++ b/lib/librte_eal/common/include/rte_memory.h
>> @@ -209,6 +209,9 @@ struct rte_memseg {
>>   */
>>  unsigned rte_memory_get_nrank(void);
>>
>> +/* check memsegs iovas are within a range based on dma mask */
>> +int rte_eal_check_dma_mask(uint8_t maskbits);
>> +
>>  /**
>>   * Drivers based on uio will not load unless physical
>>   * addresses are obtainable. It is only possible to get
>> diff --git a/lib/librte_eal/rte_eal_version.map
>> b/lib/librte_eal/rte_eal_version.map
>> index f4f46c1..aa6cf87 100644
>> --- a/lib/librte_eal/rte_eal_version.map
>> +++ b/lib/librte_eal/rte_eal_version.map
>> @@ -184,6 +184,7 @@ DPDK_17.11 {
>>
>>         rte_eal_create_uio_dev;
>>         rte_bus_get_iommu_class;
>> +       rte_eal_check_dma_mask;
>>         rte_eal_has_pci;
>>         rte_eal_iova_mode;
>>         rte_eal_mbuf_default_mempool_ops;
>> --
>> 1.9.1
>>
>