4.20-stable review patch. If anyone has any objections, please let me know.
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From: "Peter Zijlstra (Intel)" peterz@infradead.org
commit 400816f60c543153656ac74eaf7f36f6b7202378 upstream
Skylake (and later) will receive a microcode update to address a TSX errata. This microcode will, on execution of a TSX instruction (speculative or not) use (clobber) PMC3. This update will also provide a new MSR to change this behaviour along with a CPUID bit to enumerate the presence of this new MSR.
When the MSR gets set; the microcode will no longer use PMC3 but will Force Abort every TSX transaction (upon executing COMMIT).
When TSX Force Abort (TFA) is allowed (default); the MSR gets set when PMC3 gets scheduled and cleared when, after scheduling, PMC3 is unused.
When TFA is not allowed; clear PMC3 from all constraints such that it will not get used.
Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/events/intel/core.c | 74 +++++++++++++++++++++++++++++++++++++++++-- arch/x86/events/perf_event.h | 6 +++ 2 files changed, 77 insertions(+), 3 deletions(-)
--- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -1999,6 +1999,39 @@ static void intel_pmu_nhm_enable_all(int intel_pmu_enable_all(added); }
+static void intel_set_tfa(struct cpu_hw_events *cpuc, bool on) +{ + u64 val = on ? MSR_TFA_RTM_FORCE_ABORT : 0; + + if (cpuc->tfa_shadow != val) { + cpuc->tfa_shadow = val; + wrmsrl(MSR_TSX_FORCE_ABORT, val); + } +} + +static void intel_tfa_commit_scheduling(struct cpu_hw_events *cpuc, int idx, int cntr) +{ + /* + * We're going to use PMC3, make sure TFA is set before we touch it. + */ + if (cntr == 3 && !cpuc->is_fake) + intel_set_tfa(cpuc, true); +} + +static void intel_tfa_pmu_enable_all(int added) +{ + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + + /* + * If we find PMC3 is no longer used when we enable the PMU, we can + * clear TFA. + */ + if (!test_bit(3, cpuc->active_mask)) + intel_set_tfa(cpuc, false); + + intel_pmu_enable_all(added); +} + static void enable_counter_freeze(void) { update_debugctlmsr(get_debugctlmsr() | @@ -3354,6 +3387,26 @@ glp_get_event_constraints(struct cpu_hw_ return c; }
+static bool allow_tsx_force_abort = true; + +static struct event_constraint * +tfa_get_event_constraints(struct cpu_hw_events *cpuc, int idx, + struct perf_event *event) +{ + struct event_constraint *c = hsw_get_event_constraints(cpuc, idx, event); + + /* + * Without TFA we must not use PMC3. + */ + if (!allow_tsx_force_abort && test_bit(3, c->idxmsk)) { + c = dyn_constraint(cpuc, c, idx); + c->idxmsk64 &= ~(1ULL << 3); + c->weight--; + } + + return c; +} + /* * Broadwell: * @@ -3448,13 +3501,15 @@ int intel_cpuc_prepare(struct cpu_hw_eve goto err; }
- if (x86_pmu.flags & PMU_FL_EXCL_CNTRS) { + if (x86_pmu.flags & (PMU_FL_EXCL_CNTRS | PMU_FL_TFA)) { size_t sz = X86_PMC_IDX_MAX * sizeof(struct event_constraint);
cpuc->constraint_list = kzalloc_node(sz, GFP_KERNEL, cpu_to_node(cpu)); if (!cpuc->constraint_list) goto err_shared_regs; + }
+ if (x86_pmu.flags & PMU_FL_EXCL_CNTRS) { cpuc->excl_cntrs = allocate_excl_cntrs(cpu); if (!cpuc->excl_cntrs) goto err_constraint_list; @@ -3564,9 +3619,10 @@ static void free_excl_cntrs(struct cpu_h if (c->core_id == -1 || --c->refcnt == 0) kfree(c); cpuc->excl_cntrs = NULL; - kfree(cpuc->constraint_list); - cpuc->constraint_list = NULL; } + + kfree(cpuc->constraint_list); + cpuc->constraint_list = NULL; }
static void intel_pmu_cpu_dying(int cpu) @@ -4086,8 +4142,11 @@ static struct attribute *intel_pmu_caps_ NULL };
+DEVICE_BOOL_ATTR(allow_tsx_force_abort, 0644, allow_tsx_force_abort); + static struct attribute *intel_pmu_attrs[] = { &dev_attr_freeze_on_smi.attr, + NULL, /* &dev_attr_allow_tsx_force_abort.attr.attr */ NULL, };
@@ -4580,6 +4639,15 @@ __init int intel_pmu_init(void) tsx_attr = hsw_tsx_events_attrs; intel_pmu_pebs_data_source_skl( boot_cpu_data.x86_model == INTEL_FAM6_SKYLAKE_X); + + if (boot_cpu_has(X86_FEATURE_TSX_FORCE_ABORT)) { + x86_pmu.flags |= PMU_FL_TFA; + x86_pmu.get_event_constraints = tfa_get_event_constraints; + x86_pmu.enable_all = intel_tfa_pmu_enable_all; + x86_pmu.commit_scheduling = intel_tfa_commit_scheduling; + intel_pmu_attrs[1] = &dev_attr_allow_tsx_force_abort.attr.attr; + } + pr_cont("Skylake events, "); name = "skylake"; break; --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -243,6 +243,11 @@ struct cpu_hw_events { int excl_thread_id; /* 0 or 1 */
/* + * SKL TSX_FORCE_ABORT shadow + */ + u64 tfa_shadow; + + /* * AMD specific bits */ struct amd_nb *amd_nb; @@ -681,6 +686,7 @@ do { \ #define PMU_FL_EXCL_CNTRS 0x4 /* has exclusive counter requirements */ #define PMU_FL_EXCL_ENABLED 0x8 /* exclusive counter active */ #define PMU_FL_PEBS_ALL 0x10 /* all events are valid PEBS events */ +#define PMU_FL_TFA 0x20 /* deal with TSX force abort */
#define EVENT_VAR(_id) event_attr_##_id #define EVENT_PTR(_id) &event_attr_##_id.attr.attr