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Date:   Wed, 13 Jul 2022 15:50:33 +0200
From:   Claudio Imbrenda <imbrenda@linux.ibm.com>
To:     Steffen Eiden <seiden@linux.ibm.com>
Cc:     Heiko Carstens <hca@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org, nrb@linux.ibm.com
Subject: Re: [PATCH v2 1/3] s390/cpufeature: rework to allow more than only
 hwcap bits
Message-ID: <20220713155033.46259c35@p-imbrenda>
In-Reply-To: <20220713125644.16121-2-seiden@linux.ibm.com>
References: <20220713125644.16121-1-seiden@linux.ibm.com>
        <20220713125644.16121-2-seiden@linux.ibm.com>
Organization: IBM
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On Wed, 13 Jul 2022 14:56:42 +0200
Steffen Eiden <seiden@linux.ibm.com> wrote:

> From: Heiko Carstens <hca@linux.ibm.com>
> 
> Rework cpufeature implementation to allow for various cpu feature
> indications, which is not only limited to hwcap bits. This is achieved
> by adding a sequential list of cpu feature numbers, where each of them
> is mapped to an entry which indicates what this number is about.
> 
> Each entry contains a type member, which indicates what feature
> name space to look into (e.g. hwcap, or cpu facility). If wanted this
> allows also to automatically load modules only in e.g. z/VM
> configurations.
> 
> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

> ---
>  arch/s390/crypto/aes_s390.c        |  2 +-
>  arch/s390/crypto/chacha-glue.c     |  2 +-
>  arch/s390/crypto/crc32-vx.c        |  2 +-
>  arch/s390/crypto/des_s390.c        |  2 +-
>  arch/s390/crypto/ghash_s390.c      |  2 +-
>  arch/s390/crypto/prng.c            |  2 +-
>  arch/s390/crypto/sha1_s390.c       |  2 +-
>  arch/s390/crypto/sha256_s390.c     |  2 +-
>  arch/s390/crypto/sha3_256_s390.c   |  2 +-
>  arch/s390/crypto/sha3_512_s390.c   |  2 +-
>  arch/s390/crypto/sha512_s390.c     |  2 +-
>  arch/s390/include/asm/cpufeature.h | 22 +++++-----------
>  arch/s390/kernel/Makefile          |  2 +-
>  arch/s390/kernel/cpufeature.c      | 42 ++++++++++++++++++++++++++++++
>  arch/s390/kernel/processor.c       | 10 -------
>  drivers/char/hw_random/s390-trng.c |  2 +-
>  drivers/s390/crypto/pkey_api.c     |  2 +-
>  17 files changed, 63 insertions(+), 39 deletions(-)
>  create mode 100644 arch/s390/kernel/cpufeature.c
> 
> diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c
> index 1023e9d43d44..526c3f40f6a2 100644
> --- a/arch/s390/crypto/aes_s390.c
> +++ b/arch/s390/crypto/aes_s390.c
> @@ -1049,7 +1049,7 @@ static int __init aes_s390_init(void)
>  	return ret;
>  }
>  
> -module_cpu_feature_match(MSA, aes_s390_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, aes_s390_init);
>  module_exit(aes_s390_fini);
>  
>  MODULE_ALIAS_CRYPTO("aes-all");
> diff --git a/arch/s390/crypto/chacha-glue.c b/arch/s390/crypto/chacha-glue.c
> index 2ec51f339cec..7752bd314558 100644
> --- a/arch/s390/crypto/chacha-glue.c
> +++ b/arch/s390/crypto/chacha-glue.c
> @@ -121,7 +121,7 @@ static void __exit chacha_mod_fini(void)
>  		crypto_unregister_skciphers(chacha_algs, ARRAY_SIZE(chacha_algs));
>  }
>  
> -module_cpu_feature_match(VXRS, chacha_mod_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_VXRS, chacha_mod_init);
>  module_exit(chacha_mod_fini);
>  
>  MODULE_DESCRIPTION("ChaCha20 stream cipher");
> diff --git a/arch/s390/crypto/crc32-vx.c b/arch/s390/crypto/crc32-vx.c
> index fafecad20752..017143e9cef7 100644
> --- a/arch/s390/crypto/crc32-vx.c
> +++ b/arch/s390/crypto/crc32-vx.c
> @@ -298,7 +298,7 @@ static void __exit crc_vx_mod_exit(void)
>  	crypto_unregister_shashes(crc32_vx_algs, ARRAY_SIZE(crc32_vx_algs));
>  }
>  
> -module_cpu_feature_match(VXRS, crc_vx_mod_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_VXRS, crc_vx_mod_init);
>  module_exit(crc_vx_mod_exit);
>  
>  MODULE_AUTHOR("Hendrik Brueckner <brueckner@linux.vnet.ibm.com>");
> diff --git a/arch/s390/crypto/des_s390.c b/arch/s390/crypto/des_s390.c
> index e013088b5115..8e75b83a5ddc 100644
> --- a/arch/s390/crypto/des_s390.c
> +++ b/arch/s390/crypto/des_s390.c
> @@ -492,7 +492,7 @@ static int __init des_s390_init(void)
>  	return ret;
>  }
>  
> -module_cpu_feature_match(MSA, des_s390_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, des_s390_init);
>  module_exit(des_s390_exit);
>  
>  MODULE_ALIAS_CRYPTO("des");
> diff --git a/arch/s390/crypto/ghash_s390.c b/arch/s390/crypto/ghash_s390.c
> index 6b07a2f1ce8a..0800a2a5799f 100644
> --- a/arch/s390/crypto/ghash_s390.c
> +++ b/arch/s390/crypto/ghash_s390.c
> @@ -145,7 +145,7 @@ static void __exit ghash_mod_exit(void)
>  	crypto_unregister_shash(&ghash_alg);
>  }
>  
> -module_cpu_feature_match(MSA, ghash_mod_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, ghash_mod_init);
>  module_exit(ghash_mod_exit);
>  
>  MODULE_ALIAS_CRYPTO("ghash");
> diff --git a/arch/s390/crypto/prng.c b/arch/s390/crypto/prng.c
> index ae382bafc772..a077087bc6cc 100644
> --- a/arch/s390/crypto/prng.c
> +++ b/arch/s390/crypto/prng.c
> @@ -907,5 +907,5 @@ static void __exit prng_exit(void)
>  	}
>  }
>  
> -module_cpu_feature_match(MSA, prng_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, prng_init);
>  module_exit(prng_exit);
> diff --git a/arch/s390/crypto/sha1_s390.c b/arch/s390/crypto/sha1_s390.c
> index a3fabf310a38..bc3a22704e09 100644
> --- a/arch/s390/crypto/sha1_s390.c
> +++ b/arch/s390/crypto/sha1_s390.c
> @@ -95,7 +95,7 @@ static void __exit sha1_s390_fini(void)
>  	crypto_unregister_shash(&alg);
>  }
>  
> -module_cpu_feature_match(MSA, sha1_s390_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, sha1_s390_init);
>  module_exit(sha1_s390_fini);
>  
>  MODULE_ALIAS_CRYPTO("sha1");
> diff --git a/arch/s390/crypto/sha256_s390.c b/arch/s390/crypto/sha256_s390.c
> index 24983f175676..6f1ccdf93d3e 100644
> --- a/arch/s390/crypto/sha256_s390.c
> +++ b/arch/s390/crypto/sha256_s390.c
> @@ -134,7 +134,7 @@ static void __exit sha256_s390_fini(void)
>  	crypto_unregister_shash(&sha256_alg);
>  }
>  
> -module_cpu_feature_match(MSA, sha256_s390_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, sha256_s390_init);
>  module_exit(sha256_s390_fini);
>  
>  MODULE_ALIAS_CRYPTO("sha256");
> diff --git a/arch/s390/crypto/sha3_256_s390.c b/arch/s390/crypto/sha3_256_s390.c
> index 30ac49b635bf..e1350e033a32 100644
> --- a/arch/s390/crypto/sha3_256_s390.c
> +++ b/arch/s390/crypto/sha3_256_s390.c
> @@ -137,7 +137,7 @@ static void __exit sha3_256_s390_fini(void)
>  	crypto_unregister_shash(&sha3_256_alg);
>  }
>  
> -module_cpu_feature_match(MSA, sha3_256_s390_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, sha3_256_s390_init);
>  module_exit(sha3_256_s390_fini);
>  
>  MODULE_ALIAS_CRYPTO("sha3-256");
> diff --git a/arch/s390/crypto/sha3_512_s390.c b/arch/s390/crypto/sha3_512_s390.c
> index e70d50f7620f..06c142ed9bb1 100644
> --- a/arch/s390/crypto/sha3_512_s390.c
> +++ b/arch/s390/crypto/sha3_512_s390.c
> @@ -147,7 +147,7 @@ static void __exit fini(void)
>  	crypto_unregister_shash(&sha3_384_alg);
>  }
>  
> -module_cpu_feature_match(MSA, init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, init);
>  module_exit(fini);
>  
>  MODULE_LICENSE("GPL");
> diff --git a/arch/s390/crypto/sha512_s390.c b/arch/s390/crypto/sha512_s390.c
> index 43ce4956df73..04f11c407763 100644
> --- a/arch/s390/crypto/sha512_s390.c
> +++ b/arch/s390/crypto/sha512_s390.c
> @@ -142,7 +142,7 @@ static void __exit fini(void)
>  	crypto_unregister_shash(&sha384_alg);
>  }
>  
> -module_cpu_feature_match(MSA, init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, init);
>  module_exit(fini);
>  
>  MODULE_LICENSE("GPL");
> diff --git a/arch/s390/include/asm/cpufeature.h b/arch/s390/include/asm/cpufeature.h
> index 14cfd48d598e..771caf5281e5 100644
> --- a/arch/s390/include/asm/cpufeature.h
> +++ b/arch/s390/include/asm/cpufeature.h
> @@ -2,28 +2,20 @@
>  /*
>   * Module interface for CPU features
>   *
> - * Copyright IBM Corp. 2015
> + * Copyright IBM Corp. 2015, 2022
>   * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
>   */
>  
>  #ifndef __ASM_S390_CPUFEATURE_H
>  #define __ASM_S390_CPUFEATURE_H
>  
> -#include <asm/elf.h>
> +enum {
> +	S390_CPU_FEATURE_MSA,
> +	S390_CPU_FEATURE_VXRS,
> +	MAX_CPU_FEATURES
> +};
>  
> -/* Hardware features on Linux on z Systems are indicated by facility bits that
> - * are mapped to the so-called machine flags.  Particular machine flags are
> - * then used to define ELF hardware capabilities; most notably hardware flags
> - * that are essential for user space / glibc.
> - *
> - * Restrict the set of exposed CPU features to ELF hardware capabilities for
> - * now.  Additional machine flags can be indicated by values larger than
> - * MAX_ELF_HWCAP_FEATURES.
> - */
> -#define MAX_ELF_HWCAP_FEATURES	(8 * sizeof(elf_hwcap))
> -#define MAX_CPU_FEATURES	MAX_ELF_HWCAP_FEATURES
> -
> -#define cpu_feature(feat)	ilog2(HWCAP_ ## feat)
> +#define cpu_feature(feature)	(feature)
>  
>  int cpu_have_feature(unsigned int nr);
>  
> diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
> index 27d6b3c7aa06..3cbfa9fddd9a 100644
> --- a/arch/s390/kernel/Makefile
> +++ b/arch/s390/kernel/Makefile
> @@ -35,7 +35,7 @@ CFLAGS_unwind_bc.o	+= -fno-optimize-sibling-calls
>  
>  obj-y	:= traps.o time.o process.o earlypgm.o early.o setup.o idle.o vtime.o
>  obj-y	+= processor.o syscall.o ptrace.o signal.o cpcmd.o ebcdic.o nmi.o
> -obj-y	+= debug.o irq.o ipl.o dis.o diag.o vdso.o
> +obj-y	+= debug.o irq.o ipl.o dis.o diag.o vdso.o cpufeature.o
>  obj-y	+= sysinfo.o lgr.o os_info.o machine_kexec.o
>  obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
>  obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
> diff --git a/arch/s390/kernel/cpufeature.c b/arch/s390/kernel/cpufeature.c
> new file mode 100644
> index 000000000000..9044c75d8b38
> --- /dev/null
> +++ b/arch/s390/kernel/cpufeature.c
> @@ -0,0 +1,42 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright IBM Corp. 2022
> + */
> +#include <linux/cpufeature.h>
> +#include <linux/bug.h>
> +#include <asm/elf.h>
> +
> +enum {
> +	TYPE_HWCAP,
> +};
> +
> +struct s390_cpu_feature {
> +	unsigned int type	: 4;
> +	unsigned int num	: 28;
> +};
> +
> +static struct s390_cpu_feature s390_cpu_features[MAX_CPU_FEATURES] = {
> +	[S390_CPU_FEATURE_MSA]		= {.type = TYPE_HWCAP, .num = HWCAP_NR_MSA},
> +	[S390_CPU_FEATURE_VXRS]		= {.type = TYPE_HWCAP, .num = HWCAP_NR_VXRS},
> +};
> +
> +/*
> + * cpu_have_feature - Test CPU features on module initialization
> + */
> +int cpu_have_feature(unsigned int num)
> +{
> +	struct s390_cpu_feature *feature;
> +
> +	if (WARN_ON_ONCE(num >= MAX_CPU_FEATURES))
> +		return 0;
> +
> +	feature = &s390_cpu_features[num];
> +	switch (feature->type) {
> +	case TYPE_HWCAP:
> +		return !!(elf_hwcap & BIT(feature->num));
> +	default:
> +		WARN_ON_ONCE(1);
> +		return 0;
> +	}
> +}
> +EXPORT_SYMBOL(cpu_have_feature);
> diff --git a/arch/s390/kernel/processor.c b/arch/s390/kernel/processor.c
> index aa0e0e7fc773..a194611ba88c 100644
> --- a/arch/s390/kernel/processor.c
> +++ b/arch/s390/kernel/processor.c
> @@ -8,7 +8,6 @@
>  #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
>  
>  #include <linux/stop_machine.h>
> -#include <linux/cpufeature.h>
>  #include <linux/bitops.h>
>  #include <linux/kernel.h>
>  #include <linux/random.h>
> @@ -96,15 +95,6 @@ void cpu_init(void)
>  	enter_lazy_tlb(&init_mm, current);
>  }
>  
> -/*
> - * cpu_have_feature - Test CPU features on module initialization
> - */
> -int cpu_have_feature(unsigned int num)
> -{
> -	return elf_hwcap & (1UL << num);
> -}
> -EXPORT_SYMBOL(cpu_have_feature);
> -
>  static void show_facilities(struct seq_file *m)
>  {
>  	unsigned int bit;
> diff --git a/drivers/char/hw_random/s390-trng.c b/drivers/char/hw_random/s390-trng.c
> index 2beaa35c0d74..12fbac0ed8ca 100644
> --- a/drivers/char/hw_random/s390-trng.c
> +++ b/drivers/char/hw_random/s390-trng.c
> @@ -261,5 +261,5 @@ static void __exit trng_exit(void)
>  	trng_debug_exit();
>  }
>  
> -module_cpu_feature_match(MSA, trng_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, trng_init);
>  module_exit(trng_exit);
> diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
> index 7329caa7d467..5a05d1cdfec2 100644
> --- a/drivers/s390/crypto/pkey_api.c
> +++ b/drivers/s390/crypto/pkey_api.c
> @@ -2115,5 +2115,5 @@ static void __exit pkey_exit(void)
>  	pkey_debug_exit();
>  }
>  
> -module_cpu_feature_match(MSA, pkey_init);
> +module_cpu_feature_match(S390_CPU_FEATURE_MSA, pkey_init);
>  module_exit(pkey_exit);