Re: [PATCH 02/14] x86/cpu: Extract cpuid helpers to arch-independent

Williams, Dan J
2021-07-14T16:58:37Z

On Tue, 2021-07-13 at 00:04 +0200, Iwona Winiarska wrote:
> Baseboard management controllers (BMC) often run Linux but are usually
> implemented with non-X86 processors. They can use PECI to access package
> config space (PCS) registers on the host CPU and since some information,
> e.g. figuring out the core count, can be obtained using different
> registers on different CPU generations, they need to decode the family
> and model.
>
> The format of Package Identifier PCS register that describes CPUID
> information has the same layout as CPUID_1.EAX, so let's allow to reuse
> cpuid helpers by making it available for other architectures as well.

Just some minor comments below.

You can go ahead and add:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

>
> Signed-off-by: Iwona Winiarska <iwona.winiarska@intel.com>
> Reviewed-by: Tony Luck <tony.luck@intel.com>
> ---
>  MAINTAINERS                      | 2 ++
>  arch/x86/Kconfig                 | 1 +
>  arch/x86/include/asm/cpu.h       | 3 ---
>  arch/x86/include/asm/microcode.h | 2 +-
>  arch/x86/kvm/cpuid.h             | 3 ++-
>  arch/x86/lib/Makefile            | 2 +-
>  drivers/edac/mce_amd.c           | 3 +--
>  include/linux/x86/cpu.h          | 9 +++++++++
>  lib/Kconfig                      | 5 +++++
>  lib/Makefile                     | 2 ++
>  lib/x86/Makefile                 | 3 +++
>  {arch/x86/lib => lib/x86}/cpu.c  | 2 +-
>  12 files changed, 28 insertions(+), 9 deletions(-)
>  create mode 100644 include/linux/x86/cpu.h
>  create mode 100644 lib/x86/Makefile
>  rename {arch/x86/lib => lib/x86}/cpu.c (95%)
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ec5987a00800..6f77aaca2a30 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20081,6 +20081,8 @@ T:      git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/core
>  F:     Documentation/devicetree/bindings/x86/
>  F:     Documentation/x86/
>  F:     arch/x86/
> +F:     include/linux/x86/

Doesn't this technically belong in patch1 since that one introduced
the directory?

> +F:     lib/x86/
>
>  X86 ENTRY CODE
>  M:     Andy Lutomirski <luto@kernel.org>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 49270655e827..750f9b896e4f 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -141,6 +141,7 @@ config X86
>         select GENERIC_IRQ_PROBE
>         select GENERIC_IRQ_RESERVATION_MODE
>         select GENERIC_IRQ_SHOW
> +       select GENERIC_LIB_X86
>         select GENERIC_PENDING_IRQ              if SMP
>         select GENERIC_PTDUMP
>         select GENERIC_SMP_IDLE_THREAD
> diff --git a/arch/x86/include/asm/cpu.h b/arch/x86/include/asm/cpu.h
> index 33d41e350c79..2a663a05a795 100644
> --- a/arch/x86/include/asm/cpu.h
> +++ b/arch/x86/include/asm/cpu.h
> @@ -37,9 +37,6 @@ extern int _debug_hotplug_cpu(int cpu, int action);
>
>  int mwait_usable(const struct cpuinfo_x86 *);
>
> -unsigned int x86_family(unsigned int sig);
> -unsigned int x86_model(unsigned int sig);
> -unsigned int x86_stepping(unsigned int sig);
>  #ifdef CONFIG_CPU_SUP_INTEL
>  extern void __init sld_setup(struct cpuinfo_x86 *c);
>  extern void switch_to_sld(unsigned long tifn);
> diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h
> index ab45a220fac4..4b0eabf63b98 100644
> --- a/arch/x86/include/asm/microcode.h
> +++ b/arch/x86/include/asm/microcode.h
> @@ -2,9 +2,9 @@
>  #ifndef _ASM_X86_MICROCODE_H
>  #define _ASM_X86_MICROCODE_H
>
> -#include <asm/cpu.h>
>  #include <linux/earlycpio.h>
>  #include <linux/initrd.h>
> +#include <linux/x86/cpu.h>

Has this patch set received a build success notification from the
kbuild robot? I.e. are you sure that this include was only here for
the

unsigned int x86_family(unsigned int sig);
unsigned int x86_model(unsigned int sig);
unsigned int x86_stepping(unsigned int sig);

...helpers. All the other replacements look trivially verifiable as
only needing these 3 helpers.

>
>  struct ucode_patch {
>         struct list_head plist;
> diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h
> index c99edfff7f82..bf070d2a2175 100644
> --- a/arch/x86/kvm/cpuid.h
> +++ b/arch/x86/kvm/cpuid.h
> @@ -4,10 +4,11 @@
>
>  #include "x86.h"
>  #include "reverse_cpuid.h"
> -#include <asm/cpu.h>
>  #include <asm/processor.h>
>  #include <uapi/asm/kvm_para.h>
>
> +#include <linux/x86/cpu.h>
> +
>  extern u32 kvm_cpu_caps[NR_KVM_CPU_CAPS] __read_mostly;
>  void kvm_set_cpu_caps(void);
>
> diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
> index bad4dee4f0e4..fd73c1b72c3e 100644
> --- a/arch/x86/lib/Makefile
> +++ b/arch/x86/lib/Makefile
> @@ -41,7 +41,7 @@ clean-files := inat-tables.c
>
>  obj-$(CONFIG_SMP) += msr-smp.o cache-smp.o
>
> -lib-y := delay.o misc.o cmdline.o cpu.o
> +lib-y := delay.o misc.o cmdline.o
>  lib-y += usercopy_$(BITS).o usercopy.o getuser.o putuser.o
>  lib-y += memcpy_$(BITS).o
>  lib-$(CONFIG_ARCH_HAS_COPY_MC) += copy_mc.o copy_mc_64.o
> diff --git a/drivers/edac/mce_amd.c b/drivers/edac/mce_amd.c
> index 27d56920b469..f545f5fad02c 100644
> --- a/drivers/edac/mce_amd.c
> +++ b/drivers/edac/mce_amd.c
> @@ -1,8 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  #include <linux/module.h>
>  #include <linux/slab.h>
> -
> -#include <asm/cpu.h>
> +#include <linux/x86/cpu.h>
>
>  #include "mce_amd.h"
>
> diff --git a/include/linux/x86/cpu.h b/include/linux/x86/cpu.h
> new file mode 100644
> index 000000000000..5f383d47886d
> --- /dev/null
> +++ b/include/linux/x86/cpu.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef _LINUX_X86_CPU_H
> +#define _LINUX_X86_CPU_H
> +
> +unsigned int x86_family(unsigned int sig);
> +unsigned int x86_model(unsigned int sig);
> +unsigned int x86_stepping(unsigned int sig);
> +
> +#endif /* _LINUX_X86_CPU_H */
> diff --git a/lib/Kconfig b/lib/Kconfig
> index d241fe476fda..cc28bc1f2d84 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -718,3 +718,8 @@ config PLDMFW
>
>  config ASN1_ENCODER
>         tristate
> +
> +config GENERIC_LIB_X86
> +       bool
> +       depends on X86
> +       default n

No need for a "default n" line. Omitting a default is the same as
"default n".