Re: [dpdk-dev] [PATCH] kni: increase kernel version requirement for VA

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 11/20/2019 4:24 PM, Igor Ryzhov wrote:
> Hi Ferruh,
> 
> There is a typo in "version incread to > 4.9.0 ...".
> incread > increased

Thanks Igor, I will fix in next version.

> 
> Igor
> 
> On Wed, Nov 20, 2019 at 7:00 PM Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> 
>> A build error reported related to the selected
>> 'get_user_pages_remote()' kernel API:
>>
>> .../kernel/linux/kni/kni_dev.h:113:8:
>>   error: too few arguments to function ‘get_user_pages_remote’
>>   ret = get_user_pages_remote(tsk, tsk->mm, iova, 1
>>         ^~~~~~~~~~~~~~~~~~~~~
>>
>> Currently there are three version of the 'get_user_pages_remote()'
>> supported, based on kernel version
>> < 4.9, = 4.9, > 4.9
>>
>> These version based checks are not working fine with the distro kernels
>> which is the cause of reported build error. The error reported by the
>> kernel version 4.8, but it is using API defined in > 4.9.
>>
>> To be able to take control of this, and possible more, related build
>> error, increasing the minimum supported kernel version for iova=va with
>> KNI to kernel version 4.9.
>>
>> This leaves us with single version of the kernel API and more
>> manageable.
>>
>> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
>> ---
>> Cc: David Marchand <david.marchand@redhat.com>
>> Cc: Vamsi Attunuru <vattunuru@marvell.com>
>> Cc: Kiran Kumar K <kirankumark@marvell.com>
>> Cc: Jerin Jacob <jerinj@marvell.com>
>> ---
>>  doc/guides/prog_guide/kernel_nic_interface.rst |  2 +-
>>  doc/guides/rel_notes/release_19_11.rst         |  2 +-
>>  kernel/linux/kni/compat.h                      | 16 +++++-----------
>>  kernel/linux/kni/kni_dev.h                     | 10 ----------
>>  lib/librte_eal/linux/eal/eal.c                 |  6 +++---
>>  lib/librte_kni/rte_kni.c                       |  2 +-
>>  6 files changed, 11 insertions(+), 27 deletions(-)
>>
>> diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst
>> b/doc/guides/prog_guide/kernel_nic_interface.rst
>> index c4479ffbf..848b00253 100644
>> --- a/doc/guides/prog_guide/kernel_nic_interface.rst
>> +++ b/doc/guides/prog_guide/kernel_nic_interface.rst
>> @@ -305,7 +305,7 @@ IOVA = VA: Support
>>
>>  KNI operates in IOVA_VA scheme when
>>
>> -- LINUX_VERSION_CODE >= KERNEL_VERSION(4, 6, 0) and
>> +- LINUX_VERSION_CODE > KERNEL_VERSION(4, 9, 0) and
>>  - EAL option `iova-mode=va` is passed or bus IOVA scheme in the DPDK is
>> selected
>>    as RTE_IOVA_VA.
>>
>> diff --git a/doc/guides/rel_notes/release_19_11.rst
>> b/doc/guides/rel_notes/release_19_11.rst
>> index 21be600ab..45b58190c 100644
>> --- a/doc/guides/rel_notes/release_19_11.rst
>> +++ b/doc/guides/rel_notes/release_19_11.rst
>> @@ -299,7 +299,7 @@ New Features
>>    * Added IOVA = VA support for KNI, KNI can operate in IOVA = VA mode
>> when
>>      `iova-mode=va` EAL option is passed to the application or when bus
>> IOVA
>>      scheme is selected as RTE_IOVA_VA. This mode only works on Linux
>> Kernel
>> -    versions 4.6.0 and above.
>> +    versions above 4.9.0.
>>
>>    * Due to IOVA to KVA address translations, based on the KNI use case
>> there
>>      can be a performance impact. For mitigation, forcing IOVA to PA via
>> EAL
>> diff --git a/kernel/linux/kni/compat.h b/kernel/linux/kni/compat.h
>> index 062b170ef..339dd25a7 100644
>> --- a/kernel/linux/kni/compat.h
>> +++ b/kernel/linux/kni/compat.h
>> @@ -122,16 +122,10 @@
>>  #define HAVE_SIGNAL_FUNCTIONS_OWN_HEADER
>>  #endif
>>
>> -#if KERNEL_VERSION(4, 6, 0) <= LINUX_VERSION_CODE
>> -
>> +/*
>> + * iova to kva mapping support can be provided since 4.6.0, but support
>> + * version incread to > 4.9.0 because of the updates in
>> get_user_pages_remote()
>> + */
>> +#if KERNEL_VERSION(4, 9, 0) < LINUX_VERSION_CODE
>>  #define HAVE_IOVA_TO_KVA_MAPPING_SUPPORT
>> -
>> -#if KERNEL_VERSION(4, 9, 0) > LINUX_VERSION_CODE
>> -#define GET_USER_PAGES_REMOTE_API_V1
>> -#elif KERNEL_VERSION(4, 9, 0) == LINUX_VERSION_CODE
>> -#define GET_USER_PAGES_REMOTE_API_V2
>> -#else
>> -#define GET_USER_PAGES_REMOTE_API_V3
>> -#endif
>> -
>>  #endif
>> diff --git a/kernel/linux/kni/kni_dev.h b/kernel/linux/kni/kni_dev.h
>> index fb641b696..5e75c6371 100644
>> --- a/kernel/linux/kni/kni_dev.h
>> +++ b/kernel/linux/kni/kni_dev.h
>> @@ -101,18 +101,8 @@ static inline phys_addr_t iova_to_phys(struct
>> task_struct *tsk,
>>         offset = iova & (PAGE_SIZE - 1);
>>
>>         /* Read one page struct info */
>> -#ifdef GET_USER_PAGES_REMOTE_API_V3
>>         ret = get_user_pages_remote(tsk, tsk->mm, iova, 1,
>>                                     FOLL_TOUCH, &page, NULL, NULL);
>> -#endif
>> -#ifdef GET_USER_PAGES_REMOTE_API_V2
>> -       ret = get_user_pages_remote(tsk, tsk->mm, iova, 1,
>> -                                   FOLL_TOUCH, &page, NULL);
>> -#endif
>> -#ifdef GET_USER_PAGES_REMOTE_API_V1
>> -       ret = get_user_pages_remote(tsk, tsk->mm, iova, 1
>> -                                   0, 0, &page, NULL);
>> -#endif
>>         if (ret < 0)
>>                 return 0;
>>
>> diff --git a/lib/librte_eal/linux/eal/eal.c
>> b/lib/librte_eal/linux/eal/eal.c
>> index b5b71500c..5879e33e5 100644
>> --- a/lib/librte_eal/linux/eal/eal.c
>> +++ b/lib/librte_eal/linux/eal/eal.c
>> @@ -1073,7 +1073,7 @@ rte_eal_init(int argc, char **argv)
>>                                  */
>>                                 iova_mode = RTE_IOVA_VA;
>>                                 RTE_LOG(DEBUG, EAL, "Physical addresses
>> are unavailable, selecting IOVA as VA mode.\n");
>> -#if defined(RTE_LIBRTE_KNI) && LINUX_VERSION_CODE >= KERNEL_VERSION(4, 6,
>> 0)
>> +#if defined(RTE_LIBRTE_KNI) && LINUX_VERSION_CODE > KERNEL_VERSION(4, 9,
>> 0)
>>                         } else if (rte_eal_check_module("rte_kni") == 1) {
>>                                 iova_mode = RTE_IOVA_PA;
>>                                 RTE_LOG(DEBUG, EAL, "KNI is loaded,
>> selecting IOVA as PA mode for better KNI perfomance.\n");
>> @@ -1090,9 +1090,9 @@ rte_eal_init(int argc, char **argv)
>>                                 RTE_LOG(DEBUG, EAL, "IOMMU is not
>> available, selecting IOVA as PA mode.\n");
>>                         }
>>                 }
>> -#if defined(RTE_LIBRTE_KNI) && LINUX_VERSION_CODE < KERNEL_VERSION(4, 6,
>> 0)
>> +#if defined(RTE_LIBRTE_KNI) && LINUX_VERSION_CODE <= KERNEL_VERSION(4, 9,
>> 0)
>>                 /* Workaround for KNI which requires physical address to
>> work
>> -                * in kernels < 4.6
>> +                * in kernels <= 4.9
>>                  */
>>                 if (iova_mode == RTE_IOVA_VA &&
>>                                 rte_eal_check_module("rte_kni") == 1) {
>> diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c
>> index 86995fc81..b564482fe 100644
>> --- a/lib/librte_kni/rte_kni.c
>> +++ b/lib/librte_kni/rte_kni.c
>> @@ -98,7 +98,7 @@ static volatile int kni_fd = -1;
>>  int
>>  rte_kni_init(unsigned int max_kni_ifaces __rte_unused)
>>  {
>> -#if LINUX_VERSION_CODE < KERNEL_VERSION(4, 6, 0)
>> +#if LINUX_VERSION_CODE <= KERNEL_VERSION(4, 9, 0)
>>         if (rte_eal_iova_mode() != RTE_IOVA_PA) {
>>                 RTE_LOG(ERR, KNI, "KNI requires IOVA as PA\n");
>>                 return -1;
>> --
>> 2.21.0
>>
>>