odp-execute: Add ISA implementation of actions.

This commit adds the AVX512 implementation of the action functionality.

Usage:
  $ ovs-appctl odp-execute/action-impl-set avx512

Signed-off-by: Emma Finn <emma.finn@intel.com>
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Co-authored-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Sunil Pai G <sunil.pai.g@intel.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>

Documentation/topics/dpdk/bridge.rst

@@ -321,3 +321,33 @@ following command::
 ``scalar`` can be selected on core ``3`` by the following command::
 
     $ ovs-appctl dpif-netdev/miniflow-parser-set -pmd 3 scalar
+
+
+Actions Implementations (Experimental)
+--------------------------------------
+
+Actions describe what processing or modification should be performed on a
+packet when it matches a given flow. Similar to the datapath interface,
+DPCLS and MFEX (see above), the implementation of these actions can be
+accelerated using SIMD instructions, resulting in improved performance.
+
+OVS provides multiple implementations of the actions, however some
+implementations requiring a CPU capable of executing the required SIMD
+instructions.
+
+Available implementations can be listed with the following command::
+
+    $ ovs-appctl odp-execute/action-impl-show
+        Available Actions implementations:
+            scalar (available: Yes, active: Yes)
+            autovalidator (available: Yes, active: No)
+            avx512 (available: Yes, active: No)
+
+By default, ``scalar`` is used.  Implementations can be selected by
+name::
+
+    $ ovs-appctl odp-execute/action-impl-set avx512
+    Action implementation set to avx512.
+
+    $ ovs-appctl odp-execute/action-impl-set scalar
+    Action implementation set to scalar.

Documentation/topics/testing.rst

@@ -361,12 +361,12 @@ testsuite.
 Userspace datapath: Testing and Validation of CPU-specific Optimizations
 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
 
-As multiple versions of the datapath classifier and packet parsing functions
-can co-exist, each with different CPU ISA optimizations, it is important to
-validate that they all give the exact same results.  To easily test all the
-implementations, an ``autovalidator`` implementation of them exists.  This
-implementation runs all other available implementations, and verifies that the
-results are identical.
+As multiple versions of the datapath classifier, packet parsing functions and
+actions can co-exist, each with different CPU ISA optimizations, it is
+important to validate that they all give the exact same results.  To easily
+test all the implementations, an ``autovalidator`` implementation of them
+exists. This implementation runs all other available implementations, and
+verifies that the results are identical.
 
 Running the OVS unit tests with the autovalidator enabled ensures all
 implementations provide the same results.  Note that the performance of the
@@ -382,18 +382,26 @@ To set the autovalidator for the packet parser, use this command::
 
     $ ovs-appctl dpif-netdev/miniflow-parser-set autovalidator
 
+To set the autovalidator for actions, use this command::
+
+    $ ovs-appctl odp-execute/action-impl-set autovalidator
+
 To run the OVS unit test suite with the autovalidator as the default
 implementation, it is required to recompile OVS.  During the recompilation,
 the default priority of the `autovalidator` implementation is set to the
-maximum priority, ensuring every test will be run with every implementation::
+maximum priority, ensuring every test will be run with every implementation.
+Priority is only related to mfex autovalidator and not the actions
+autovalidator.::
 
-    $ ./configure --enable-autovalidator --enable-mfex-default-autovalidator
+    $ ./configure --enable-autovalidator --enable-mfex-default-autovalidator \
+        --enable-actions-default-autovalidator
 
 The following line should be seen in the configuration log when the above
 options are used::
 
     checking whether DPCLS Autovalidator is default implementation... yes
     checking whether MFEX Autovalidator is default implementation... yes
+    checking whether actions Autovalidator is default implementation... yes
 
 Compile OVS in debug mode to have `ovs_assert` statements error out if
 there is a mis-match in the datapath classifier lookup or packet parser

NEWS

@@ -61,6 +61,7 @@ Post-v2.17.0
        implementations available at run time.
      * Add build time configure command to enable auto-validator as default
        actions implementation at build time.
+     * Add AVX512 implementation of actions.
    - Linux datapath:
      * Add offloading meter tc police.
      * Add support for offloading the check_pkt_len action.

acinclude.m4

@@ -96,6 +96,7 @@ dnl
 dnl Checks if compiler and binutils supports various AVX512 ISA.
 AC_DEFUN([OVS_CHECK_AVX512], [
   OVS_CHECK_BINUTILS_AVX512
+  OVS_CHECK_GCC_AVX512VL
   OVS_CONDITIONAL_CC_OPTION_DEFINE([-mavx512f], [HAVE_AVX512F])
   OVS_CONDITIONAL_CC_OPTION_DEFINE([-mavx512bw], [HAVE_AVX512BW])
   OVS_CONDITIONAL_CC_OPTION_DEFINE([-mavx512vl], [HAVE_AVX512VL])

lib/cpu.c

@@ -53,6 +53,7 @@ X86_ISA(X86_EXT_FEATURES_LEAF, EBX, 16, OVS_CPU_ISA_X86_AVX512F)
 X86_ISA(X86_EXT_FEATURES_LEAF, EBX, 30, OVS_CPU_ISA_X86_AVX512BW)
 X86_ISA(X86_EXT_FEATURES_LEAF, ECX,  1, OVS_CPU_ISA_X86_AVX512VBMI)
 X86_ISA(X86_EXT_FEATURES_LEAF, ECX, 14, OVS_CPU_ISA_X86_VPOPCNTDQ)
+X86_ISA(X86_EXT_FEATURES_LEAF, EBX, 31, OVS_CPU_ISA_X86_AVX512VL)
 #endif
 
 bool

lib/cpu.h

@@ -25,6 +25,7 @@ enum ovs_cpu_isa {
     OVS_CPU_ISA_X86_AVX512F,
     OVS_CPU_ISA_X86_AVX512BW,
     OVS_CPU_ISA_X86_AVX512VBMI,
+    OVS_CPU_ISA_X86_AVX512VL,
     OVS_CPU_ISA_X86_VPOPCNTDQ,
     OVS_CPU_ISA_X86_LAST = OVS_CPU_ISA_X86_VPOPCNTDQ,
 };

lib/odp-execute-private.c

@@ -41,6 +41,14 @@ static struct odp_execute_action_impl action_impls[] = {
         .name = "scalar",
         .init_func = odp_action_scalar_init,
     },
+
+#if ACTION_IMPL_AVX512_CHECK
+    [ACTION_IMPL_AVX512] = {
+        .available = false,
+        .name = "avx512",
+        .init_func = NULL,
+    },
+#endif
 };
 
 static void

lib/odp-execute-private.h

@@ -22,6 +22,14 @@
 #include "odp-netlink.h"
 #include "ovs-atomic.h"
 
+/* Combine all required ISA and Linker checks into a single #define
+ * for readability and simplicity where the checks are needed. Note
+ * that it is always #defined, so code must use the #if preprocesor
+ * directive (not #ifdef). */
+#define ACTION_IMPL_AVX512_CHECK (__x86_64__ && HAVE_AVX512F \
+    && HAVE_LD_AVX512_GOOD && __SSE4_2__ && HAVE_AVX512BW && HAVE_AVX512VL \
+    && HAVE_GCC_AVX512VL_GOOD)
+
 /* Forward declaration for typedef. */
 struct odp_execute_action_impl;
 
@@ -56,6 +64,10 @@ enum odp_execute_action_impl_idx {
      * Do not change the autovalidator position in this list without updating
      * the define below. */
 
+#if ACTION_IMPL_AVX512_CHECK
+    ACTION_IMPL_AVX512,
+#endif
+
     ACTION_IMPL_MAX,
 };
 

m4/openvswitch.m4

@@ -421,6 +421,35 @@ AC_DEFUN([OVS_CHECK_SPHINX],
    AC_ARG_VAR([SPHINXBUILD])
    AM_CONDITIONAL([HAVE_SPHINX], [test "$SPHINXBUILD" != none])])
 
+
+dnl Checks for compiler correctly emitting AVX512-VL vpermd instruction.
+dnl GCC5 says it exports AVX512-VL, but it doesn't implement "vpermd" instruction
+dnl resulting in compilation failures. To workaround this "reported vs actual"
+dnl mismatch, we compile a small snippet, and conditionally enable AVX512-VL.
+AC_DEFUN([OVS_CHECK_GCC_AVX512VL], [
+  AC_MSG_CHECKING([whether compiler correctly emits AVX512-VL])
+  AC_COMPILE_IFELSE(
+    [AC_LANG_PROGRAM([#include <immintrin.h>
+                     static void __attribute__((__target__("avx512vl")))
+                     check_permutexvar(void)
+                     {
+                         __m256i v_swap32a = _mm256_setr_epi32(0x0, 0x4, 0xF,
+                                                               0xF, 0xF, 0xF,
+                                                               0xF, 0xF);
+                         v_swap32a = _mm256_permutexvar_epi32(v_swap32a,
+                                                              v_swap32a);
+                     }],[])],
+    [AC_MSG_RESULT([yes])
+    ovs_cv_gcc_avx512vl_good=yes],
+    [AC_MSG_RESULT([no])
+    ovs_cv_gcc_avx512vl_good=no])
+   if test "$ovs_cv_gcc_avx512vl_good" = yes; then
+     AC_DEFINE([HAVE_GCC_AVX512VL_GOOD], [1],
+               [Define to 1 if gcc implements the vpermd instruction.])
+   fi
+   AM_CONDITIONAL([HAVE_GCC_AVX512VL_GOOD],
+                  [test "$ovs_cv_gcc_avx512vl_good" = yes])])
+
 dnl Checks for binutils/assembler known issue with AVX512.
 dnl Due to backports, we probe assembling a reproducer instead of checking
 dnl binutils version string. More details, including ASM dumps and debug here: