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perf/x86/intel: Implement support for TSX Force Abort

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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>
This commit is contained in:
Peter Zijlstra (Intel) 2019-03-05 22:23:18 +01:00 committed by Thomas Gleixner
parent 52f6490940
commit 400816f60c
2 changed files with 77 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

74
arch/x86/events/intel/core.c
View file

@ -1999,6 +1999,39 @@ static void intel_pmu_nhm_enable_all(int added)
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_events *cpuc, int idx,
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_events *cpuc, int cpu)
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_hw_events *cpuc)
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_attrs[] = {
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;

6
arch/x86/events/perf_event.h
View file

@ -242,6 +242,11 @@ struct cpu_hw_events {
struct intel_excl_cntrs *excl_cntrs;
int excl_thread_id; /* 0 or 1 */
/*
* SKL TSX_FORCE_ABORT shadow
*/
u64 tfa_shadow;
/*
* AMD specific bits
*/
@ -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