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

[Alejandro Lucero]

On Tue, Jul 10, 2018 at 11:06 AM, Eelco Chaudron <echaudro at redhat.com>
wrote:

>
>
> On 10 Jul 2018, at 11:34, Alejandro Lucero wrote:
>
> 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;
>>>>
>>>
> Looking at some other code, it looks like NULL entries might exists. So
> should a continue; rather than a break; be used here?
>
>
I do not think so. memsegs are allocated sequentially, so first with addr
as NULL implies no more memsegs.


>
> +
>>>> +               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
>>>>
>>>>
>>>
>
>