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    Subject[PATCH 6.0 055/862] arm64: topology: move store_cpu_topology() to shared code
    Date
    From: Conor Dooley <conor.dooley@microchip.com>

    commit 456797da792fa7cbf6698febf275fe9b36691f78 upstream.

    arm64's method of defining a default cpu topology requires only minimal
    changes to apply to RISC-V also. The current arm64 implementation exits
    early in a uniprocessor configuration by reading MPIDR & claiming that
    uniprocessor can rely on the default values.

    This is appears to be a hangover from prior to '3102bc0e6ac7 ("arm64:
    topology: Stop using MPIDR for topology information")', because the
    current code just assigns default values for multiprocessor systems.

    With the MPIDR references removed, store_cpu_topolgy() can be moved to
    the common arch_topology code.

    Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
    Acked-by: Catalin Marinas <catalin.marinas@arm.com>
    Reviewed-by: Atish Patra <atishp@rivosinc.com>
    Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/arm64/kernel/topology.c | 40 ----------------------------------------
    drivers/base/arch_topology.c | 19 +++++++++++++++++++
    2 files changed, 19 insertions(+), 40 deletions(-)

    --- a/arch/arm64/kernel/topology.c
    +++ b/arch/arm64/kernel/topology.c
    @@ -22,46 +22,6 @@
    #include <asm/cputype.h>
    #include <asm/topology.h>

    -void store_cpu_topology(unsigned int cpuid)
    -{
    - struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
    - u64 mpidr;
    -
    - if (cpuid_topo->package_id != -1)
    - goto topology_populated;
    -
    - mpidr = read_cpuid_mpidr();
    -
    - /* Uniprocessor systems can rely on default topology values */
    - if (mpidr & MPIDR_UP_BITMASK)
    - return;
    -
    - /*
    - * This would be the place to create cpu topology based on MPIDR.
    - *
    - * However, it cannot be trusted to depict the actual topology; some
    - * pieces of the architecture enforce an artificial cap on Aff0 values
    - * (e.g. GICv3's ICC_SGI1R_EL1 limits it to 15), leading to an
    - * artificial cycling of Aff1, Aff2 and Aff3 values. IOW, these end up
    - * having absolutely no relationship to the actual underlying system
    - * topology, and cannot be reasonably used as core / package ID.
    - *
    - * If the MT bit is set, Aff0 *could* be used to define a thread ID, but
    - * we still wouldn't be able to obtain a sane core ID. This means we
    - * need to entirely ignore MPIDR for any topology deduction.
    - */
    - cpuid_topo->thread_id = -1;
    - cpuid_topo->core_id = cpuid;
    - cpuid_topo->package_id = cpu_to_node(cpuid);
    -
    - pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
    - cpuid, cpuid_topo->package_id, cpuid_topo->core_id,
    - cpuid_topo->thread_id, mpidr);
    -
    -topology_populated:
    - update_siblings_masks(cpuid);
    -}
    -
    #ifdef CONFIG_ACPI
    static bool __init acpi_cpu_is_threaded(int cpu)
    {
    --- a/drivers/base/arch_topology.c
    +++ b/drivers/base/arch_topology.c
    @@ -841,4 +841,23 @@ void __init init_cpu_topology(void)
    return;
    }
    }
    +
    +void store_cpu_topology(unsigned int cpuid)
    +{
    + struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
    +
    + if (cpuid_topo->package_id != -1)
    + goto topology_populated;
    +
    + cpuid_topo->thread_id = -1;
    + cpuid_topo->core_id = cpuid;
    + cpuid_topo->package_id = cpu_to_node(cpuid);
    +
    + pr_debug("CPU%u: package %d core %d thread %d\n",
    + cpuid, cpuid_topo->package_id, cpuid_topo->core_id,
    + cpuid_topo->thread_id);
    +
    +topology_populated:
    + update_siblings_masks(cpuid);
    +}
    #endif

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