[RFC PATCH] net/af_xdp: use libxdp if available

[Ciara Loftus <ciara.loftus@intel.com>]

AF_XDP support is deprecated in libbpf since v0.7.0 [1]. The
libxdp library now provides the functionality which once was in
libbpf and which the AF_XDP PMD relies on. This commit updates the
AF_XDP meson build to use the libxdp library if available. If it
is not available, only versions of libbpf prior to v0.7.0 are
allowed, as they still contain the required AF_XDP functionality.

libbpf still remains a dependency even if libxdp is present, as we
use libbpf APIs for program loading.

[1] https://github.com/libbpf/libbpf/commit/277846bc6c15

Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
---
 doc/guides/nics/af_xdp.rst             |  4 +--
 doc/guides/rel_notes/release_22_03.rst |  4 +++
 drivers/net/af_xdp/compat.h            |  4 +++
 drivers/net/af_xdp/meson.build         | 45 +++++++++++++++++++++-----
 drivers/net/af_xdp/rte_eth_af_xdp.c    |  1 -
 5 files changed, 46 insertions(+), 12 deletions(-)

diff --git a/doc/guides/nics/af_xdp.rst b/doc/guides/nics/af_xdp.rst
index c9d0e1ad6c..966f713c11 100644
--- a/doc/guides/nics/af_xdp.rst
+++ b/doc/guides/nics/af_xdp.rst
@@ -43,9 +43,7 @@ Prerequisites
 This is a Linux-specific PMD, thus the following prerequisites apply:
 
 *  A Linux Kernel (version > v4.18) with XDP sockets configuration enabled;
-*  libbpf (within kernel version > v5.1-rc4) with latest af_xdp support installed,
-   User can install libbpf via `make install_lib` && `make install_headers` in
-   <kernel src tree>/tools/lib/bpf;
+*  Both libxdp and libbpf libraries installed, or, libbpf <=v0.6.0
 *  A Kernel bound interface to attach to;
 *  For need_wakeup feature, it requires kernel version later than v5.3-rc1;
 *  For PMD zero copy, it requires kernel version later than v5.4-rc1;
diff --git a/doc/guides/rel_notes/release_22_03.rst b/doc/guides/rel_notes/release_22_03.rst
index 6d99d1eaa9..acf0f66fa8 100644
--- a/doc/guides/rel_notes/release_22_03.rst
+++ b/doc/guides/rel_notes/release_22_03.rst
@@ -55,6 +55,10 @@ New Features
      Also, make sure to start the actual text at the margin.
      =======================================================
 
+* **Update AF_XDP PMD**
+
+  * Added libxdp support.
+
 
 Removed Items
 -------------
diff --git a/drivers/net/af_xdp/compat.h b/drivers/net/af_xdp/compat.h
index 3880dc7dd7..245df1b109 100644
--- a/drivers/net/af_xdp/compat.h
+++ b/drivers/net/af_xdp/compat.h
@@ -2,7 +2,11 @@
  * Copyright(c) 2020 Intel Corporation.
  */
 
+#ifdef RTE_LIBRTE_AF_XDP_PMD_LIBXDP
+#include <xdp/xsk.h>
+#else
 #include <bpf/xsk.h>
+#endif
 #include <linux/version.h>
 #include <poll.h>
 
diff --git a/drivers/net/af_xdp/meson.build b/drivers/net/af_xdp/meson.build
index 3ed2b29784..dc4f53352e 100644
--- a/drivers/net/af_xdp/meson.build
+++ b/drivers/net/af_xdp/meson.build
@@ -9,19 +9,48 @@ endif
 
 sources = files('rte_eth_af_xdp.c')
 
+xdp_dep = dependency('libxdp', required: false, method: 'pkg-config')
+if not xdp_dep.found()
+    xdp_dep = cc.find_library('xdp', required: false)
+endif
+
 bpf_dep = dependency('libbpf', required: false, method: 'pkg-config')
 if not bpf_dep.found()
     bpf_dep = cc.find_library('bpf', required: false)
 endif
 
-if bpf_dep.found() and cc.has_header('bpf/xsk.h') and cc.has_header('linux/if_xdp.h')
-    ext_deps += bpf_dep
-    bpf_ver_dep = dependency('libbpf', version : '>=0.2.0',
-            required: false, method: 'pkg-config')
-    if bpf_ver_dep.found()
-        dpdk_conf.set('RTE_LIBRTE_AF_XDP_PMD_SHARED_UMEM', 1)
+if cc.has_header('linux/if_xdp.h')
+    if xdp_dep.found() and cc.has_header('xdp/xsk.h')
+        if bpf_dep.found() and cc.has_header('bpf/bpf.h')
+            dpdk_conf.set('RTE_LIBRTE_AF_XDP_PMD_LIBXDP', 1)
+            dpdk_conf.set('RTE_LIBRTE_AF_XDP_PMD_SHARED_UMEM', 1)
+            ext_deps += xdp_dep
+            ext_deps += bpf_dep
+        else
+            build = false
+            reason = 'missing dependency, libbpf'
+        endif
+    elif bpf_dep.found() and cc.has_header('bpf/xsk.h') and cc.has_header('bpf/bpf.h')
+        # libxdp not found. Rely solely on libbpf for xsk functionality
+        # which is only available in versions <= v0.6.0.
+        bpf_ver_dep = dependency('libbpf', version : '<=0.6.0',
+                                 required: false, method: 'pkg-config')
+        if bpf_ver_dep.found()
+            ext_deps += bpf_dep
+            bpf_shumem_ver_dep = dependency('libbpf', version : '>=0.2.0',
+                            required: false, method: 'pkg-config')
+            if bpf_shumem_ver_dep.found()
+                dpdk_conf.set('RTE_LIBRTE_AF_XDP_PMD_SHARED_UMEM', 1)
+            endif
+        else
+            build = false
+            reason = 'missing dependency, "libxdp" or "libbpf <= v0.6.0"'
+        endif
+    else
+        build = false
+        reason = 'missing dependency, "libxdp" and "libbpf"'
     endif
 else
     build = false
-    reason = 'missing dependency, "libbpf"'
-endif
+    reason = 'missing header, "linux/if_xdp.h"'
+endif
\ No newline at end of file
diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
index 96c2c9d939..5d89bebb01 100644
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -16,7 +16,6 @@
 #include <linux/sockios.h>
 #include "af_xdp_deps.h"
 #include <bpf/bpf.h>
-#include <bpf/xsk.h>
 
 #include <rte_ethdev.h>
 #include <ethdev_driver.h>
-- 
2.17.1