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    Subject[PATCH v1 14/20] x86/resctrl: Abstract __rmid_read()
    Date
    __rmid_read() selects the specified eventid and returns the counter
    value from the msr. The error handling is architecture specific, and
    handled by the callers, rdtgroup_mondata_show() and __mon_event_count().

    Error handling should be handled by architecture specific code, as
    a different architecture may have different requirements. MPAM's
    counters can report that they are 'not ready', requiring a second
    read after a short delay. This should be hidden from resctrl.

    Make __rmid_read() the architecture specific function for reading
    a counter. Rename it resctrl_arch_rmid_read() and move the error
    handling into it.

    Signed-off-by: James Morse <james.morse@arm.com>
    ---
    arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 4 +--
    arch/x86/kernel/cpu/resctrl/internal.h | 2 +-
    arch/x86/kernel/cpu/resctrl/monitor.c | 44 ++++++++++++++---------
    include/linux/resctrl.h | 1 +
    4 files changed, 31 insertions(+), 20 deletions(-)

    diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
    index 5104f39928fd..3269ee954941 100644
    --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
    +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
    @@ -579,9 +579,9 @@ int rdtgroup_mondata_show(struct seq_file *m, void *arg)

    mon_event_read(&rr, r, d, rdtgrp, evtid, false);

    - if (rr.val & RMID_VAL_ERROR)
    + if (rr.err == -EIO)
    seq_puts(m, "Error\n");
    - else if (rr.val & RMID_VAL_UNAVAIL)
    + else if (rr.err == -EINVAL)
    seq_puts(m, "Unavailable\n");
    else
    seq_printf(m, "%llu\n", rr.val * hw_res->mon_scale);
    diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
    index f3f31315a907..eca7793d3342 100644
    --- a/arch/x86/kernel/cpu/resctrl/internal.h
    +++ b/arch/x86/kernel/cpu/resctrl/internal.h
    @@ -40,7 +40,6 @@
    */
    #define MBM_CNTR_WIDTH_OFFSET_MAX (62 - MBM_CNTR_WIDTH_BASE)

    -
    struct rdt_fs_context {
    struct kernfs_fs_context kfc;
    bool enable_cdpl2;
    @@ -94,6 +93,7 @@ struct rmid_read {
    struct rdt_domain *d;
    enum resctrl_event_id evtid;
    bool first;
    + int err;
    u64 val;
    };

    diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
    index 3b8b29470a5c..e7c43c40ff28 100644
    --- a/arch/x86/kernel/cpu/resctrl/monitor.c
    +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
    @@ -164,9 +164,9 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_domain *d,
    memset(m, 0, sizeof(*m));
    }

    -static u64 __rmid_read(u32 rmid, enum resctrl_event_id eventid)
    +int resctrl_arch_rmid_read(u32 rmid, enum resctrl_event_id eventid, u64 *val)
    {
    - u64 val;
    + u64 msr_val;

    /*
    * As per the SDM, when IA32_QM_EVTSEL.EvtID (bits 7:0) is configured
    @@ -177,14 +177,24 @@ static u64 __rmid_read(u32 rmid, enum resctrl_event_id eventid)
    * are error bits.
    */
    wrmsr(MSR_IA32_QM_EVTSEL, eventid, rmid);
    - rdmsrl(MSR_IA32_QM_CTR, val);
    + rdmsrl(MSR_IA32_QM_CTR, msr_val);

    - return val;
    + if (msr_val & RMID_VAL_ERROR)
    + return -EIO;
    + if (msr_val & RMID_VAL_UNAVAIL)
    + return -EINVAL;
    +
    + *val = msr_val;
    +
    + return 0;
    }

    static bool rmid_dirty(struct rmid_entry *entry)
    {
    - u64 val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
    + u64 val = 0;
    +
    + if (resctrl_arch_rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID, &val))
    + return true;

    return val >= resctrl_cqm_threshold;
    }
    @@ -256,8 +266,8 @@ static void add_rmid_to_limbo(struct rmid_entry *entry)
    {
    struct rdt_resource *r;
    struct rdt_domain *d;
    - int cpu;
    - u64 val;
    + int cpu, err;
    + u64 val = 0;

    r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;

    @@ -265,8 +275,10 @@ static void add_rmid_to_limbo(struct rmid_entry *entry)
    cpu = get_cpu();
    list_for_each_entry(d, &r->domains, list) {
    if (cpumask_test_cpu(cpu, &d->cpu_mask)) {
    - val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
    - if (val <= resctrl_cqm_threshold)
    + err = resctrl_arch_rmid_read(entry->rmid,
    + QOS_L3_OCCUP_EVENT_ID,
    + &val);
    + if (err || val <= resctrl_cqm_threshold)
    continue;
    }

    @@ -316,16 +328,15 @@ static int __mon_event_count(u32 rmid, struct rmid_read *rr)
    {
    struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);
    struct mbm_state *m;
    - u64 chunks, tval;
    + u64 chunks, tval = 0;

    if (rr->first)
    resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid);

    - tval = __rmid_read(rmid, rr->evtid);
    - if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL)) {
    - rr->val = tval;
    + rr->err = resctrl_arch_rmid_read(rmid, rr->evtid, &tval);
    + if (rr->err)
    return -EINVAL;
    - }
    +
    switch (rr->evtid) {
    case QOS_L3_OCCUP_EVENT_ID:
    rr->val += tval;
    @@ -361,10 +372,9 @@ static void mbm_bw_count(u32 rmid, struct rmid_read *rr)
    {
    struct rdt_hw_resource *hw_res = resctrl_to_arch_res(rr->r);
    struct mbm_state *m = &rr->d->mbm_local[rmid];
    - u64 tval, cur_bw, chunks, bw_chunks;
    + u64 tval = 0, cur_bw, chunks, bw_chunks;

    - tval = __rmid_read(rmid, rr->evtid);
    - if (tval & (RMID_VAL_ERROR | RMID_VAL_UNAVAIL))
    + if (resctrl_arch_rmid_read(rmid, rr->evtid, &tval))
    return;

    chunks = mbm_overflow_count(m->prev_msr, tval, hw_res->mbm_width);
    diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
    index 79e83ce3dfbc..543f6d0599a9 100644
    --- a/include/linux/resctrl.h
    +++ b/include/linux/resctrl.h
    @@ -228,6 +228,7 @@ void resctrl_arch_get_config(struct rdt_resource *r, struct rdt_domain *d,
    u32 *value);
    int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d);
    void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d);
    +int resctrl_arch_rmid_read(u32 rmid, enum resctrl_event_id eventid, u64 *res);

    /**
    * resctrl_arch_reset_rmid() - Reset any private state associated with rmid
    --
    2.30.2
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