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ovs/lib/dpif-netdev-lookup.h
David Marchand fe171e4f10 dpif-netdev: Refactor AVX512 runtime checks.
As described in the bugzilla below, cpu_has_isa code may be compiled
with some AVX512 instructions in it, because cpu.c is built as part of
the libopenvswitchavx512.
This is a problem when this function (supposed to probe for AVX512
instructions availability) is invoked from generic OVS code, on older
CPUs that don't support them.

For the same reason, dpcls_subtable_avx512_gather_probe,
dp_netdev_input_outer_avx512_probe, mfex_avx512_probe and
mfex_avx512_vbmi_probe are potential runtime bombs and can't either be
built as part of libopenvswitchavx512.

Move cpu.c to be part of the "normal" libopenvswitch.
And move other helpers in generic OVS code.

Note:
- dpcls_subtable_avx512_gather_probe is split in two, because it also
  needs to do its own magic,
- while moving those helpers, prefer direct calls to cpu_has_isa and
  avoid cast to intermediate integer variables when a simple boolean
  is enough,

Fixes: 352b6c7116cd ("dpif-lookup: add avx512 gather implementation.")
Fixes: abb807e27dd4 ("dpif-netdev: Add command to switch dpif implementation.")
Fixes: 250ceddcc2d0 ("dpif-netdev/mfex: Add AVX512 based optimized miniflow extract")
Fixes: b366fa2f4947 ("dpif-netdev: Call cpuid for x86 isa availability.")
Reported-at: https://bugzilla.redhat.com/2100393
Reported-by: Ales Musil <amusil@redhat.com>
Co-authored-by: Ales Musil <amusil@redhat.com>
Signed-off-by: Ales Musil <amusil@redhat.com>
Signed-off-by: David Marchand <david.marchand@redhat.com>
Acked-by: Sunil Pai G <sunil.pai.g@intel.com>
Acked-by: Ales Musil <amusil@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
2022-06-29 11:27:09 +02:00

93 lines
3.4 KiB
C

/*
* Copyright (c) 2020 Intel Corporation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef DPIF_NETDEV_LOOKUP_H
#define DPIF_NETDEV_LOOKUP_H 1
#include <config.h>
#include "dpif-netdev.h"
#include "dpif-netdev-private-dpcls.h"
#include "dpif-netdev-private-thread.h"
/* Function to perform a probe for the subtable bit fingerprint.
* Returns NULL if not valid, or a valid function pointer to call for this
* subtable on success.
*/
typedef
dpcls_subtable_lookup_func (*dpcls_subtable_probe_func)(uint32_t u0_bit_count,
uint32_t u1_bit_count);
/* Prototypes for subtable implementations */
dpcls_subtable_lookup_func
dpcls_subtable_autovalidator_probe(uint32_t u0_bit_count,
uint32_t u1_bit_count);
/* Probe function to select a specialized version of the generic lookup
* implementation. This provides performance benefit due to compile-time
* optimizations such as loop-unrolling. These are enabled by the compile-time
* constants in the specific function implementations.
*/
dpcls_subtable_lookup_func
dpcls_subtable_generic_probe(uint32_t u0_bit_count, uint32_t u1_bit_count);
/* Probe function for AVX-512 gather implementation */
dpcls_subtable_lookup_func
dpcls_subtable_avx512_gather_probe__(uint32_t u0_bit_cnt, uint32_t u1_bit_cnt,
bool use_vpop);
/* Subtable registration and iteration helpers */
struct dpcls_subtable_lookup_info_t {
/* higher priority gets used over lower values. This allows deployments
* to select the best implementation for the use-case.
*/
uint8_t prio;
/* Probe function: tests if the (u0,u1) combo is supported. If not
* supported, this function returns NULL. If supported, a function pointer
* is returned which when called will perform the lookup on the subtable.
*/
dpcls_subtable_probe_func probe;
/* Human readable name, used in setting subtable priority commands */
const char *name;
/* Counter which holds the usage count of each implementations. */
atomic_count usage_cnt;
};
int dpcls_subtable_set_prio(const char *name, uint8_t priority);
void dpcls_info_inc_usage(struct dpcls_subtable_lookup_info_t *info);
void dpcls_info_dec_usage(struct dpcls_subtable_lookup_info_t *info);
/* Lookup the best subtable lookup implementation for the given u0,u1 count. */
dpcls_subtable_lookup_func
dpcls_subtable_get_best_impl(uint32_t u0_bit_count, uint32_t u1_bit_count,
struct dpcls_subtable_lookup_info_t **info);
/* Retrieve the array of lookup implementations for iteration.
* On error, returns a negative number.
* On success, returns the size of the arrays pointed to by the out parameter.
*/
int
dpcls_subtable_lookup_info_get(struct dpcls_subtable_lookup_info_t **out_ptr);
/* Prints dpcls subtables in use for different implementations. */
void
dpcls_impl_print_stats(struct ds *reply);
#endif /* dpif-netdev-lookup.h */