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    Subject[PATCH v1 12/20] x86/recstrl: Add per-rmid arch private storage for overflow and chunks
    Date
    resctrl_arch_rmid_read() is intended as the function that an
    architecture agnostic resctrl filesystem driver can use to
    read a value in bytes from a counter. Currently the function returns
    the mbm values in chunks directly from hardware. For bandwidth
    counters the resctrl filesystem provides the number of bytes
    ever seen. Internally mba_sc uses a second prev_bw_msr to calculate
    the bytes read since the last mba_sc invocation.

    MPAM's scaling of counters can be changed at runtime, reducing the
    resolution but increasing the range. When this is changed the prev_msr
    values need to be converted by the architecture code.

    Add storage for per-rmid private storage. The prev_msr and chunks
    values will move here to allow resctrl_arch_rmid_read() to always
    return the number of bytes read by this counter.

    Signed-off-by: James Morse <james.morse@arm.com>
    ---
    arch/x86/kernel/cpu/resctrl/core.c | 29 ++++++++++++++++++++++++++
    arch/x86/kernel/cpu/resctrl/internal.h | 13 ++++++++++++
    2 files changed, 42 insertions(+)

    diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
    index 8a3c13c6c19f..27c93d12ca27 100644
    --- a/arch/x86/kernel/cpu/resctrl/core.c
    +++ b/arch/x86/kernel/cpu/resctrl/core.c
    @@ -432,6 +432,28 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain *d)
    return 0;
    }

    +static int arch_domain_mbm_alloc(u32 num_rmid, struct rdt_hw_domain *hw_dom)
    +{
    + size_t tsize;
    +
    + if (is_mbm_total_enabled()) {
    + tsize = sizeof(*hw_dom->arch_mbm_total);
    + hw_dom->arch_mbm_total = kcalloc(num_rmid, tsize, GFP_KERNEL);
    + if (!hw_dom->arch_mbm_total)
    + return -ENOMEM;
    + }
    + if (is_mbm_local_enabled()) {
    + tsize = sizeof(*hw_dom->arch_mbm_local);
    + hw_dom->arch_mbm_local = kcalloc(num_rmid, tsize, GFP_KERNEL);
    + if (!hw_dom->arch_mbm_local) {
    + kfree(hw_dom->arch_mbm_total);
    + return -ENOMEM;
    + }
    + }
    +
    + return 0;
    +}
    +
    /*
    * domain_add_cpu - Add a cpu to a resource's domain list.
    *
    @@ -481,6 +503,11 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
    return;
    }

    + if (r->mon_capable && arch_domain_mbm_alloc(r->num_rmid, hw_dom)) {
    + kfree(d);
    + return;
    + }
    +
    list_add_tail(&d->list, add_pos);

    err = resctrl_online_domain(r, d);
    @@ -516,6 +543,8 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
    d->plr->d = NULL;

    kfree(hw_dom->ctrl_val);
    + kfree(hw_dom->arch_mbm_total);
    + kfree(hw_dom->arch_mbm_local);
    kfree(hw_dom);
    return;
    }
    diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
    index 0a5721e1cc07..aaae900a8ef3 100644
    --- a/arch/x86/kernel/cpu/resctrl/internal.h
    +++ b/arch/x86/kernel/cpu/resctrl/internal.h
    @@ -303,17 +303,30 @@ struct mbm_state {
    bool delta_comp;
    };

    +/**
    + * struct arch_mbm_state - values used to compute resctrl_arch_rmid_read()s
    + * return value.
    + * @prev_msr Value of IA32_QM_CTR for this RMID last time we read it
    + */
    +struct arch_mbm_state {
    + u64 prev_msr;
    +};
    +
    /**
    * struct rdt_hw_domain - Arch private attributes of a set of CPUs that share
    * a resource
    * @d_resctrl: Properties exposed to the resctrl file system
    * @ctrl_val: array of cache or mem ctrl values (indexed by CLOSID)
    + * @arch_mbm_total: arch private state for MBM total bandwidth
    + * @arch_mbm_local: arch private state for MBM local bandwidth
    *
    * Members of this structure are accessed via helpers that provide abstraction.
    */
    struct rdt_hw_domain {
    struct rdt_domain d_resctrl;
    u32 *ctrl_val;
    + struct arch_mbm_state *arch_mbm_total;
    + struct arch_mbm_state *arch_mbm_local;
    };

    static inline struct rdt_hw_domain *resctrl_to_arch_dom(struct rdt_domain *r)
    --
    2.30.2
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