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

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

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