RE: [PATCH v5 01/13] meson: Introduce new instruction set enqcmd to the build system.

[Liu, Yuan1]

> -----Original Message-----
> From: Yichen Wang <yichen.wang@bytedance.com>
> Sent: Friday, July 12, 2024 5:53 AM
> To: Paolo Bonzini <pbonzini@redhat.com>; Marc-André Lureau
> <marcandre.lureau@redhat.com>; Daniel P. Berrangé <berrange@redhat.com>;
> Thomas Huth <thuth@redhat.com>; Philippe Mathieu-Daudé
> <philmd@linaro.org>; Peter Xu <peterx@redhat.com>; Fabiano Rosas
> <farosas@suse.de>; Eric Blake <eblake@redhat.com>; Markus Armbruster
> <armbru@redhat.com>; Michael S. Tsirkin <mst@redhat.com>; Cornelia Huck
> <cohuck@redhat.com>; qemu-devel@nongnu.org
> Cc: Hao Xiang <hao.xiang@linux.dev>; Liu, Yuan1 <yuan1.liu@intel.com>;
> Kumar, Shivam <shivam.kumar1@nutanix.com>; Ho-Ren (Jack) Chuang
> <horenchuang@bytedance.com>; Wang, Yichen <yichen.wang@bytedance.com>
> Subject: [PATCH v5 01/13] meson: Introduce new instruction set enqcmd to
> the build system.
> 
> From: Hao Xiang <hao.xiang@linux.dev>
> 
> Enable instruction set enqcmd in build.
> 
> Signed-off-by: Hao Xiang <hao.xiang@linux.dev>
> Signed-off-by: Yichen Wang <yichen.wang@bytedance.com>
> ---
>  meson.build                   | 14 ++++++++++++++
>  meson_options.txt             |  2 ++
>  scripts/meson-buildoptions.sh |  3 +++
>  3 files changed, 19 insertions(+)
> 
> diff --git a/meson.build b/meson.build
> index 6a93da48e1..af650cfabf 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -2893,6 +2893,20 @@ config_host_data.set('CONFIG_AVX512BW_OPT',
> get_option('avx512bw') \
>      int main(int argc, char *argv[]) { return bar(argv[0]); }
>    '''), error_message: 'AVX512BW not available').allowed())
> 
> +config_host_data.set('CONFIG_DSA_OPT', get_option('enqcmd') \
> +  .require(have_cpuid_h, error_message: 'cpuid.h not available, cannot
> enable ENQCMD') \
> +  .require(cc.links('''
> +    #include <stdint.h>
> +    #include <cpuid.h>
> +    #include <immintrin.h>
> +    static int __attribute__((target("enqcmd"))) bar(void *a) {
> +      uint64_t dst[8] = { 0 };
> +      uint64_t src[8] = { 0 };
> +      return _enqcmd(dst, src);
> +    }
> +    int main(int argc, char *argv[]) { return bar(argv[argc - 1]); }
> +  '''), error_message: 'ENQCMD not available').allowed())
> +

How about using cpuid instruction to dynamically detect enqcmd and movdir64b 
instructions? 

My reasons are as follows
1. enqcmd/movdir64b and DSA devices are used together. DSA devices are 
dynamically
   detected, so enqcmd can also dynamically detect.

   Simple code for dynamically detect movdir64b and enqcmd
   bool check_dsa_instructions(void) {
       uint32_t eax, ebx, ecx, edx;
       bool movedirb_enabled;
       bool enqcmd_enabled;

       cpuid(0x07, 0x0, &eax, &ebx, &ecx, &edx);
       movedirb_enabled = (ecx >> 28) & 0x1;
       if (!movedirb_enabled) {
           return false;
       }
       enqcmd_enabled = (ecx >> 29) & 0x1;
       if (!enqcmd_enabled) {
           return false;
       }
       return true;
    }
    
https://cdrdv2-public.intel.com/819680/architecture-instruction-set-extensions-programming-reference.pdf

2. The enqcmd/movdir64b are new instructions, I checked they are integrated 
into GCC10
   However, users do not need gcc10 or higher to use two instructions.
   Simple code to implement enqcmd
   static inline int enqcmd(volatile void *reg, struct dsa_hw_desc *desc)
   {
       uint8_t retry;
       asm volatile (".byte 0xf2, 0x0f, 0x38, 0xf8, 0x02\t\n"
       "setz %0\t\n":"=r" (retry):"a"(reg), "d"(desc));
       return (int)retry;
   } 
   
file:///C:/Users/yliu80/Downloads/353216-data-streaming-accelerator-user-guide-002.pdf

>  # For both AArch64 and AArch32, detect if builtins are available.
>  config_host_data.set('CONFIG_ARM_AES_BUILTIN', cc.compiles('''
>      #include <arm_neon.h>
> diff --git a/meson_options.txt b/meson_options.txt
> index 0269fa0f16..4ed820bb8d 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -121,6 +121,8 @@ option('avx2', type: 'feature', value: 'auto',
>         description: 'AVX2 optimizations')
>  option('avx512bw', type: 'feature', value: 'auto',
>         description: 'AVX512BW optimizations')
> +option('enqcmd', type: 'feature', value: 'disabled',
> +       description: 'ENQCMD optimizations')
>  option('keyring', type: 'feature', value: 'auto',
>         description: 'Linux keyring support')
>  option('libkeyutils', type: 'feature', value: 'auto',
> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
> index cfadb5ea86..280e117687 100644
> --- a/scripts/meson-buildoptions.sh
> +++ b/scripts/meson-buildoptions.sh
> @@ -95,6 +95,7 @@ meson_options_help() {
>    printf "%s\n" '  auth-pam        PAM access control'
>    printf "%s\n" '  avx2            AVX2 optimizations'
>    printf "%s\n" '  avx512bw        AVX512BW optimizations'
> +  printf "%s\n" '  enqcmd          ENQCMD optimizations'
>    printf "%s\n" '  blkio           libblkio block device driver'
>    printf "%s\n" '  bochs           bochs image format support'
>    printf "%s\n" '  bpf             eBPF support'
> @@ -239,6 +240,8 @@ _meson_option_parse() {
>      --disable-avx2) printf "%s" -Davx2=disabled ;;
>      --enable-avx512bw) printf "%s" -Davx512bw=enabled ;;
>      --disable-avx512bw) printf "%s" -Davx512bw=disabled ;;
> +    --enable-enqcmd) printf "%s" -Denqcmd=enabled ;;
> +    --disable-enqcmd) printf "%s" -Denqcmd=disabled ;;
>      --enable-gcov) printf "%s" -Db_coverage=true ;;
>      --disable-gcov) printf "%s" -Db_coverage=false ;;
>      --enable-lto) printf "%s" -Db_lto=true ;;
> --
> Yichen Wang