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    Subject[PATCH 4.19 19/25] x86/cpu: Add a steppings field to struct x86_cpu_id
    Date
    From: Mark Gross <mgross@linux.intel.com>

    commit e9d7144597b10ff13ff2264c059f7d4a7fbc89ac upstream

    Intel uses the same family/model for several CPUs. Sometimes the
    stepping must be checked to tell them apart.

    On x86 there can be at most 16 steppings. Add a steppings bitmask to
    x86_cpu_id and a X86_MATCH_VENDOR_FAMILY_MODEL_STEPPING_FEATURE macro
    and support for matching against family/model/stepping.

    [ bp: Massage.
    tglx: Lightweight variant for backporting ]

    Signed-off-by: Mark Gross <mgross@linux.intel.com>
    Signed-off-by: Borislav Petkov <bp@suse.de>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Reviewed-by: Tony Luck <tony.luck@intel.com>
    Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/x86/include/asm/cpu_device_id.h | 27 +++++++++++++++++++++++++++
    arch/x86/kernel/cpu/match.c | 7 ++++++-
    include/linux/mod_devicetable.h | 6 ++++++
    3 files changed, 39 insertions(+), 1 deletion(-)

    --- a/arch/x86/include/asm/cpu_device_id.h
    +++ b/arch/x86/include/asm/cpu_device_id.h
    @@ -9,6 +9,33 @@

    #include <linux/mod_devicetable.h>

    +#define X86_STEPPINGS(mins, maxs) GENMASK(maxs, mins)
    +
    +/**
    + * X86_MATCH_VENDOR_FAM_MODEL_STEPPINGS_FEATURE - Base macro for CPU matching
    + * @_vendor: The vendor name, e.g. INTEL, AMD, HYGON, ..., ANY
    + * The name is expanded to X86_VENDOR_@_vendor
    + * @_family: The family number or X86_FAMILY_ANY
    + * @_model: The model number, model constant or X86_MODEL_ANY
    + * @_steppings: Bitmask for steppings, stepping constant or X86_STEPPING_ANY
    + * @_feature: A X86_FEATURE bit or X86_FEATURE_ANY
    + * @_data: Driver specific data or NULL. The internal storage
    + * format is unsigned long. The supplied value, pointer
    + * etc. is casted to unsigned long internally.
    + *
    + * Backport version to keep the SRBDS pile consistant. No shorter variants
    + * required for this.
    + */
    +#define X86_MATCH_VENDOR_FAM_MODEL_STEPPINGS_FEATURE(_vendor, _family, _model, \
    + _steppings, _feature, _data) { \
    + .vendor = X86_VENDOR_##_vendor, \
    + .family = _family, \
    + .model = _model, \
    + .steppings = _steppings, \
    + .feature = _feature, \
    + .driver_data = (unsigned long) _data \
    +}
    +
    extern const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match);

    #endif
    --- a/arch/x86/kernel/cpu/match.c
    +++ b/arch/x86/kernel/cpu/match.c
    @@ -34,13 +34,18 @@ const struct x86_cpu_id *x86_match_cpu(c
    const struct x86_cpu_id *m;
    struct cpuinfo_x86 *c = &boot_cpu_data;

    - for (m = match; m->vendor | m->family | m->model | m->feature; m++) {
    + for (m = match;
    + m->vendor | m->family | m->model | m->steppings | m->feature;
    + m++) {
    if (m->vendor != X86_VENDOR_ANY && c->x86_vendor != m->vendor)
    continue;
    if (m->family != X86_FAMILY_ANY && c->x86 != m->family)
    continue;
    if (m->model != X86_MODEL_ANY && c->x86_model != m->model)
    continue;
    + if (m->steppings != X86_STEPPING_ANY &&
    + !(BIT(c->x86_stepping) & m->steppings))
    + continue;
    if (m->feature != X86_FEATURE_ANY && !cpu_has(c, m->feature))
    continue;
    return m;
    --- a/include/linux/mod_devicetable.h
    +++ b/include/linux/mod_devicetable.h
    @@ -621,6 +621,10 @@ struct mips_cdmm_device_id {
    /*
    * MODULE_DEVICE_TABLE expects this struct to be called x86cpu_device_id.
    * Although gcc seems to ignore this error, clang fails without this define.
    + *
    + * Note: The ordering of the struct is different from upstream because the
    + * static initializers in kernels < 5.7 still use C89 style while upstream
    + * has been converted to proper C99 initializers.
    */
    #define x86cpu_device_id x86_cpu_id
    struct x86_cpu_id {
    @@ -629,6 +633,7 @@ struct x86_cpu_id {
    __u16 model;
    __u16 feature; /* bit index */
    kernel_ulong_t driver_data;
    + __u16 steppings;
    };

    #define X86_FEATURE_MATCH(x) \
    @@ -637,6 +642,7 @@ struct x86_cpu_id {
    #define X86_VENDOR_ANY 0xffff
    #define X86_FAMILY_ANY 0
    #define X86_MODEL_ANY 0
    +#define X86_STEPPING_ANY 0
    #define X86_FEATURE_ANY 0 /* Same as FPU, you can't test for that */

    /*

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