Re: [PATCH v5 1/7] eal/loongarch: support LoongArch architecture

[David Marchand <david.marchand@redhat.com>]

This is only a first pass.

On Wed, Aug 24, 2022 at 10:31 AM Min Zhou <zhoumin@loongson.cn> wrote:
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 32ffdd1a61..f00b82b5ce 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -311,6 +311,12 @@ F: config/riscv/
>  F: doc/guides/linux_gsg/cross_build_dpdk_for_riscv.rst
>  F: lib/eal/riscv/
>
> +LoongArch
> +M: Min Zhou <zhoumin@loongson.cn>
> +F: config/loongarch/
> +F: doc/guides/linux_gsg/cross_build_dpdk_for_loongarch.rst
> +F: lib/eal/loongarch/
> +

I tried to put entries in MAINTAINERS in a pseudo alphabetical order
(ignoring the vendor name).
We currently have: ARM, Power, RISC-V, X86.

As a consequence, the block for LoongArch should be moved between ARM,
and Power arches.


>  Intel x86
>  M: Bruce Richardson <bruce.richardson@intel.com>
>  M: Konstantin Ananyev <konstantin.v.ananyev@yandex.ru>

[snip]

> diff --git a/config/loongarch/meson.build b/config/loongarch/meson.build
> new file mode 100644
> index 0000000000..e052fbad7f
> --- /dev/null
> +++ b/config/loongarch/meson.build
> @@ -0,0 +1,43 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2022 Loongson Technology Corporation Limited
> +
> +if not dpdk_conf.get('RTE_ARCH_64')
> +    error('Only 64-bit compiles are supported for this platform type')
> +endif
> +dpdk_conf.set('RTE_ARCH', 'loongarch')
> +dpdk_conf.set('RTE_ARCH_LOONGARCH', 1)
> +dpdk_conf.set('RTE_ARCH_NO_VECTOR', 1)

?
RTE_ARCH_NO_VECTOR is not used anywhere, please remove.


> +
> +machine_args_generic = [
> +    ['default', ['-march=loongarch64']],
> +]
> +
> +flags_generic = [
> +    ['RTE_MACHINE', '"loongarch64"'],
> +    ['RTE_MAX_LCORE', 64],
> +    ['RTE_MAX_NUMA_NODES', 16],
> +    ['RTE_CACHE_LINE_SIZE', 64]]
> +
> +impl_generic = ['Generic loongarch', flags_generic, machine_args_generic]
> +
> +machine = []
> +machine_args = []
> +
> +machine = impl_generic
> +impl_pn = 'default'
> +
> +message('Implementer : ' + machine[0])
> +foreach flag: machine[1]
> +    if flag.length() > 0
> +        dpdk_conf.set(flag[0], flag[1])
> +    endif
> +endforeach
> +
> +foreach marg: machine[2]
> +    if marg[0] == impl_pn
> +        foreach f: marg[1]
> +           machine_args += f
> +        endforeach
> +    endif
> +endforeach
> +message(machine_args)

[snip]

> diff --git a/doc/guides/linux_gsg/index.rst b/doc/guides/linux_gsg/index.rst
> index 747552c385..c34966b241 100644
> --- a/doc/guides/linux_gsg/index.rst
> +++ b/doc/guides/linux_gsg/index.rst
> @@ -15,6 +15,7 @@ Getting Started Guide for Linux
>      build_dpdk
>      cross_build_dpdk_for_arm64
>      cross_build_dpdk_for_riscv
> +    cross_build_dpdk_for_loongarch

In alphabetical order please.


>      linux_drivers
>      build_sample_apps
>      linux_eal_parameters
> diff --git a/doc/guides/nics/features.rst b/doc/guides/nics/features.rst
> index 7f6cb914a5..8afa7ef7fd 100644
> --- a/doc/guides/nics/features.rst
> +++ b/doc/guides/nics/features.rst
> @@ -848,6 +848,12 @@ rv64
>  Support 64-bit RISC-V architecture.
>
>
> +LoongArch64
> +-----------
> +
> +Support 64-bit LoongArch architecture.
> +
> +

Idem.


>  x86-32
>  ------
>
> diff --git a/doc/guides/nics/features/default.ini b/doc/guides/nics/features/default.ini
> index d1db0c256a..8bbc4600bd 100644
> --- a/doc/guides/nics/features/default.ini
> +++ b/doc/guides/nics/features/default.ini
> @@ -73,6 +73,7 @@ ARMv7                =
>  ARMv8                =
>  Power8               =
>  rv64                 =
> +LoongArch64          =

Idem.


>  x86-32               =
>  x86-64               =
>  Usage doc            =
> diff --git a/doc/guides/rel_notes/release_22_11.rst b/doc/guides/rel_notes/release_22_11.rst
> index 8c021cf050..126160d683 100644
> --- a/doc/guides/rel_notes/release_22_11.rst
> +++ b/doc/guides/rel_notes/release_22_11.rst
> @@ -55,6 +55,12 @@ New Features
>       Also, make sure to start the actual text at the margin.
>       =======================================================
>
> +* **Added initial LoongArch architecture support.**
> +
> +  Added EAL implementation for LoongArch architecture. The initial devices
> +  the porting was tested on included Loongson 3A5000, Loongson 3C5000 and
> +  Loongson 3C5000L. In theory this implementation should work with any target
> +  based on ``LoongArch`` ISA.

Sections in the release notes are separated with two empty lines.

>
>  Removed Items
>  -------------

[snip]

> diff --git a/lib/eal/loongarch/include/meson.build b/lib/eal/loongarch/include/meson.build
> new file mode 100644
> index 0000000000..d5699c5373
> --- /dev/null
> +++ b/lib/eal/loongarch/include/meson.build
> @@ -0,0 +1,21 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright(c) 2022 Loongson Technology Corporation Limited
> +
> +arch_headers = files(
> +       'rte_atomic.h',
> +       'rte_byteorder.h',
> +       'rte_cpuflags.h',
> +       'rte_cycles.h',
> +       'rte_io.h',
> +       'rte_mcslock.h',
> +       'rte_memcpy.h',
> +       'rte_pause.h',
> +       'rte_pflock.h',
> +       'rte_power_intrinsics.h',
> +       'rte_prefetch.h',
> +       'rte_rwlock.h',
> +       'rte_spinlock.h',
> +       'rte_ticketlock.h',
> +       'rte_vect.h',
> +)

msclock, pflock and ticketlock are now non-arch specific headers.
They can be removed from the loongarch include directory.
See: e5e613f05b8c ("eal: remove unused arch-specific headers for locks")


> +install_headers(arch_headers, subdir: get_option('include_subdir_arch'))
> diff --git a/lib/eal/loongarch/include/rte_atomic.h b/lib/eal/loongarch/include/rte_atomic.h
> new file mode 100644
> index 0000000000..8e007e7f76
> --- /dev/null
> +++ b/lib/eal/loongarch/include/rte_atomic.h
> @@ -0,0 +1,253 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef _RTE_ATOMIC_LOONGARCH_H_
> +#define _RTE_ATOMIC_LOONGARCH_H_
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#include <stdint.h>
> +#include "generic/rte_atomic.h"
> +
> +/**
> + * LoongArch Synchronize
> + */
> +static inline void synchronize(void)

This name is too generic.
Plus all memory barriers are implemented in the same way.

I suggest defining rte_mb() as this inline helper.


> +{
> +       __asm__ __volatile__("dbar 0":::"memory");
> +}
> +
> +/**
> + * General memory barrier.
> + *
> + * Guarantees that the LOAD and STORE operations generated before the
> + * barrier occur before the LOAD and STORE operations generated after.
> + * This function is architecture dependent.

Those comments are copied from the generic header which is used for
doxygen, but you don't need them in the arch specific header.
Please remove.

> + */
> +#define rte_mb() synchronize()
> +
> +/**
> + * Write memory barrier.
> + *
> + * Guarantees that the STORE operations generated before the barrier
> + * occur before the STORE operations generated after.
> + * This function is architecture dependent.
> + */
> +#define rte_wmb() synchronize()
> +
> +/**
> + * Read memory barrier.
> + *
> + * Guarantees that the LOAD operations generated before the barrier
> + * occur before the LOAD operations generated after.
> + * This function is architecture dependent.
> + */
> +#define rte_rmb() synchronize()
> +
> +#define rte_smp_mb() rte_mb()
> +
> +#define rte_smp_wmb() rte_mb()
> +
> +#define rte_smp_rmb() rte_mb()
> +
> +#define rte_io_mb() rte_mb()
> +
> +#define rte_io_wmb() rte_mb()
> +
> +#define rte_io_rmb() rte_mb()
> +
> +static __rte_always_inline void
> +rte_atomic_thread_fence(int memorder)
> +{
> +       __atomic_thread_fence(memorder);
> +}
> +
> +#ifndef RTE_FORCE_INTRINSICS

Unless I missed something, there is no loongarch specific
implementations when RTE_FORCE_INTRINSICS is unset.
What is the point of supporting the case where RTE_FORCE_INTRINSICS is
undefined?

If there is no need, force-set RTE_FORCE_INTRINSICS in config and then
update headers accordingly.


> +/*------------------------- 16 bit atomic operations -------------------------*/
> +static inline int
> +rte_atomic16_cmpset(volatile uint16_t *dst, uint16_t exp, uint16_t src)
> +{
> +       return __sync_bool_compare_and_swap(dst, exp, src);
> +}
> +
> +static inline uint16_t
> +rte_atomic16_exchange(volatile uint16_t *dst, uint16_t val)
> +{
> +#if defined(__clang__)
> +       return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
> +#else
> +       return __atomic_exchange_2(dst, val, __ATOMIC_SEQ_CST);
> +#endif
> +}
> +
> +static inline void
> +rte_atomic16_inc(rte_atomic16_t *v)
> +{
> +       rte_atomic16_add(v, 1);
> +}
> +
> +static inline void
> +rte_atomic16_dec(rte_atomic16_t *v)
> +{
> +       rte_atomic16_sub(v, 1);
> +}
> +
> +static inline int rte_atomic16_inc_and_test(rte_atomic16_t *v)
> +{
> +       return __sync_add_and_fetch(&v->cnt, 1) == 0;
> +}
> +
> +static inline int rte_atomic16_dec_and_test(rte_atomic16_t *v)
> +{
> +       return __sync_sub_and_fetch(&v->cnt, 1) == 0;
> +}
> +
> +static inline int rte_atomic16_test_and_set(rte_atomic16_t *v)
> +{
> +       return rte_atomic16_cmpset((volatile uint16_t *)&v->cnt, 0, 1);
> +}
> +
> +/*------------------------- 32 bit atomic operations -------------------------*/
> +static inline int
> +rte_atomic32_cmpset(volatile uint32_t *dst, uint32_t exp, uint32_t src)
> +{
> +       return __sync_bool_compare_and_swap(dst, exp, src);
> +}
> +
> +static inline uint32_t
> +rte_atomic32_exchange(volatile uint32_t *dst, uint32_t val)
> +{
> +#if defined(__clang__)
> +       return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
> +#else
> +       return __atomic_exchange_4(dst, val, __ATOMIC_SEQ_CST);
> +#endif
> +}
> +
> +static inline void
> +rte_atomic32_inc(rte_atomic32_t *v)
> +{
> +       rte_atomic32_add(v, 1);
> +}
> +
> +static inline void
> +rte_atomic32_dec(rte_atomic32_t *v)
> +{
> +       rte_atomic32_sub(v, 1);
> +}
> +
> +static inline int rte_atomic32_inc_and_test(rte_atomic32_t *v)
> +{
> +       return __sync_add_and_fetch(&v->cnt, 1) == 0;
> +}
> +
> +static inline int rte_atomic32_dec_and_test(rte_atomic32_t *v)
> +{
> +       return __sync_sub_and_fetch(&v->cnt, 1) == 0;
> +}
> +
> +static inline int rte_atomic32_test_and_set(rte_atomic32_t *v)
> +{
> +       return rte_atomic32_cmpset((volatile uint32_t *)&v->cnt, 0, 1);
> +}
> +
> +/*------------------------- 64 bit atomic operations -------------------------*/
> +static inline int
> +rte_atomic64_cmpset(volatile uint64_t *dst, uint64_t exp, uint64_t src)
> +{
> +       return __sync_bool_compare_and_swap(dst, exp, src);
> +}
> +
> +static inline uint64_t
> +rte_atomic64_exchange(volatile uint64_t *dst, uint64_t val)
> +{
> +#if defined(__clang__)
> +       return __atomic_exchange_n(dst, val, __ATOMIC_SEQ_CST);
> +#else
> +       return __atomic_exchange_8(dst, val, __ATOMIC_SEQ_CST);
> +#endif
> +}
> +
> +static inline void
> +rte_atomic64_init(rte_atomic64_t *v)
> +{
> +       v->cnt = 0;
> +}
> +
> +static inline int64_t
> +rte_atomic64_read(rte_atomic64_t *v)
> +{
> +       return v->cnt;
> +}
> +
> +static inline void
> +rte_atomic64_set(rte_atomic64_t *v, int64_t new_value)
> +{
> +       v->cnt = new_value;
> +}
> +
> +static inline void
> +rte_atomic64_add(rte_atomic64_t *v, int64_t inc)
> +{
> +       __sync_fetch_and_add(&v->cnt, inc);
> +}
> +
> +static inline void
> +rte_atomic64_sub(rte_atomic64_t *v, int64_t dec)
> +{
> +       __sync_fetch_and_sub(&v->cnt, dec);
> +}
> +
> +static inline void
> +rte_atomic64_inc(rte_atomic64_t *v)
> +{
> +       rte_atomic64_add(v, 1);
> +}
> +
> +static inline void
> +rte_atomic64_dec(rte_atomic64_t *v)
> +{
> +       rte_atomic64_sub(v, 1);
> +}
> +
> +static inline int64_t
> +rte_atomic64_add_return(rte_atomic64_t *v, int64_t inc)
> +{
> +       return __sync_add_and_fetch(&v->cnt, inc);
> +}
> +
> +static inline int64_t
> +rte_atomic64_sub_return(rte_atomic64_t *v, int64_t dec)
> +{
> +       return __sync_sub_and_fetch(&v->cnt, dec);
> +}
> +
> +static inline int rte_atomic64_inc_and_test(rte_atomic64_t *v)
> +{
> +       return rte_atomic64_add_return(v, 1) == 0;
> +}
> +
> +static inline int rte_atomic64_dec_and_test(rte_atomic64_t *v)
> +{
> +       return rte_atomic64_sub_return(v, 1) == 0;
> +}
> +
> +static inline int rte_atomic64_test_and_set(rte_atomic64_t *v)
> +{
> +       return rte_atomic64_cmpset((volatile uint64_t *)&v->cnt, 0, 1);
> +}
> +
> +static inline void rte_atomic64_clear(rte_atomic64_t *v)
> +{
> +       rte_atomic64_set(v, 0);
> +}
> +#endif
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_ATOMIC_LOONGARCH_H_ */

[snip]

> diff --git a/lib/eal/loongarch/include/rte_cycles.h b/lib/eal/loongarch/include/rte_cycles.h
> new file mode 100644
> index 0000000000..1f8f957faf
> --- /dev/null
> +++ b/lib/eal/loongarch/include/rte_cycles.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef _RTE_CYCLES_LOONGARCH_H_
> +#define _RTE_CYCLES_LOONGARCH_H_
> +
> +#ifdef __cplusplus
> +extern "C" {
> +#endif
> +
> +#include "generic/rte_cycles.h"
> +
> +static inline uint64_t
> +get_cycle_count(void)

Same comment as earlier for memory barriers, this name is too generic.
Prefer rte_rdtsc() as the name for this helper.


> +{
> +       uint64_t count;
> +
> +       __asm__ __volatile__ (
> +               "rdtime.d %[cycles], $zero\n"
> +               : [cycles] "=r" (count)
> +               ::
> +               );
> +       return count;
> +}
> +
> +/**
> + * Read the time base register.
> + *
> + * @return
> + *   The time base for this lcore.
> + */
> +static inline uint64_t
> +rte_rdtsc(void)
> +{
> +       return get_cycle_count();
> +}
> +
> +static inline uint64_t
> +rte_rdtsc_precise(void)
> +{
> +       rte_mb();
> +       return rte_rdtsc();
> +}
> +
> +static inline uint64_t
> +rte_get_tsc_cycles(void) { return rte_rdtsc(); }
> +
> +#ifdef __cplusplus
> +}
> +#endif
> +
> +#endif /* _RTE_CYCLES_LOONGARCH_H_ */

[snip]

> diff --git a/lib/eal/loongarch/rte_cpuflags.c b/lib/eal/loongarch/rte_cpuflags.c
> new file mode 100644
> index 0000000000..4abcd0fdb3
> --- /dev/null
> +++ b/lib/eal/loongarch/rte_cpuflags.c
> @@ -0,0 +1,94 @@
> +/*
> + * SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2022 Loongson Technology Corporation Limited
> + */
> +
> +#include "rte_cpuflags.h"
> +
> +#include <elf.h>
> +#include <fcntl.h>
> +#include <assert.h>
> +#include <unistd.h>
> +#include <string.h>
> +
> +/* Symbolic values for the entries in the auxiliary table */
> +#define AT_HWCAP  16
> +#define AT_HWCAP2 26

AT_HWCAP2 is not used.


> +
> +/* software based registers */
> +enum cpu_register_t {
> +       REG_NONE = 0,
> +       REG_HWCAP,
> +       REG_MAX
> +};
> +
> +typedef uint32_t hwcap_registers_t[REG_MAX];
> +
> +struct feature_entry {
> +       uint32_t reg;
> +       uint32_t bit;
> +#define CPU_FLAG_NAME_MAX_LEN 64
> +       char name[CPU_FLAG_NAME_MAX_LEN];
> +};
> +
> +#define FEAT_DEF(name, reg, bit) \
> +       [RTE_CPUFLAG_##name] = {reg, bit, #name},
> +
> +const struct feature_entry rte_cpu_feature_table[] = {
> +       FEAT_DEF(CPUCFG,             REG_HWCAP,   0)
> +       FEAT_DEF(LAM,                REG_HWCAP,   1)
> +       FEAT_DEF(UAL,                REG_HWCAP,   2)
> +       FEAT_DEF(FPU,                REG_HWCAP,   3)
> +       FEAT_DEF(LSX,                REG_HWCAP,   4)
> +       FEAT_DEF(LASX,               REG_HWCAP,   5)
> +       FEAT_DEF(CRC32,              REG_HWCAP,   6)
> +       FEAT_DEF(COMPLEX,            REG_HWCAP,   7)
> +       FEAT_DEF(CRYPTO,             REG_HWCAP,   8)
> +       FEAT_DEF(LVZ,                REG_HWCAP,   9)
> +       FEAT_DEF(LBT_X86,            REG_HWCAP,  10)
> +       FEAT_DEF(LBT_ARM,            REG_HWCAP,  11)
> +       FEAT_DEF(LBT_MIPS,           REG_HWCAP,  12)
> +};
> +
> +/*
> + * Read AUXV software register and get cpu features for LoongArch
> + */
> +static void
> +rte_cpu_get_features(hwcap_registers_t out)
> +{
> +       out[REG_HWCAP] = rte_cpu_getauxval(AT_HWCAP);
> +}
> +
> +/*
> + * Checks if a particular flag is available on current machine.
> + */
> +int
> +rte_cpu_get_flag_enabled(enum rte_cpu_flag_t feature)
> +{
> +       const struct feature_entry *feat;
> +       hwcap_registers_t regs = {0};
> +
> +       if (feature >= RTE_CPUFLAG_NUMFLAGS)
> +               return -ENOENT;
> +
> +       feat = &rte_cpu_feature_table[feature];
> +       if (feat->reg == REG_NONE)
> +               return -EFAULT;
> +
> +       rte_cpu_get_features(regs);
> +       return (regs[feat->reg] >> feat->bit) & 1;
> +}
> +
> +const char *
> +rte_cpu_get_flag_name(enum rte_cpu_flag_t feature)
> +{
> +       if (feature >= RTE_CPUFLAG_NUMFLAGS)
> +               return NULL;
> +       return rte_cpu_feature_table[feature].name;
> +}
> +
> +void
> +rte_cpu_get_intrinsics_support(struct rte_cpu_intrinsics *intrinsics)
> +{
> +       memset(intrinsics, 0, sizeof(*intrinsics));
> +}

[snip]


-- 
David Marchand