[PATCH 05/23] perf/x86: Allow exclude_host events to run in non-root mode

[Zide Chen]

On Intel, exclude_host events are prevented from running by masking
the Global Ctrl bits with ~cpuc->intel_ctrl_guest_mask.

When PMU partitioning is enabled, the host is allowed to run
exclude_host events in non-root mode, while such events still need to
be masked in root mode, since there are no other checkpoints to stop
them from being scheduled in.

Add x86_pmu_partition_loaded() to distinguish scheduling constraints
from x86_pmu_partition_nmi_active(), as PMU partitioning constraints
apply in both the _PARTITION_PRELOAD and _PARTITION_NMI states.

Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
---
 arch/x86/events/core.c       | 11 +++++++++++
 arch/x86/events/intel/core.c |  6 ++++--
 arch/x86/events/perf_event.h |  1 +
 3 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index bbae68c49063..76af9cfaf0ad 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1813,6 +1813,17 @@ bool x86_pmu_partition_nmi_active(void)
 	       state == GUEST_PMU_PARTITION_NMI;
 }
 
+/*
+ * Skip for "fake" cpuc used during event validation, where
+ * per-CPU state like guest_pmu_state is meaningless.
+ */
+bool x86_pmu_partition_loaded(struct cpu_hw_events *cpuc)
+{
+	return !cpuc->is_fake &&
+	       pmu_partition_configured() &&
+	       this_cpu_read(guest_pmu_state) != GUEST_PMU_NONE;
+}
+
 u64 x86_pmu_current_partition_mask(void)
 {
 	return this_cpu_ptr(&cpu_hw_events)->partition_mask;
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index c595c86ecf90..894f98eb871a 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -2812,8 +2812,10 @@ static void __intel_pmu_enable_all(int added, bool pmi)
 		cpuc->active_fixed_ctrl_val = cpuc->fixed_ctrl_val;
 	}
 
-	wrmsrq(MSR_CORE_PERF_GLOBAL_CTRL,
-	       intel_ctrl & ~cpuc->intel_ctrl_guest_mask);
+	if (!x86_pmu_partition_loaded(cpuc))
+	       intel_ctrl &= ~cpuc->intel_ctrl_guest_mask;
+
+	wrmsrq(MSR_CORE_PERF_GLOBAL_CTRL, intel_ctrl);
 
 	if (test_bit(INTEL_PMC_IDX_FIXED_BTS, cpuc->active_mask)) {
 		struct perf_event *event =
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index d9875f3e6c8c..fa3023c355d5 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -1610,6 +1610,7 @@ static inline int is_pebs_pt(struct perf_event *event)
 
 bool pmu_partition_configured(void);
 bool x86_pmu_partition_nmi_active(void);
+bool x86_pmu_partition_loaded(struct cpu_hw_events *cpuc);
 u64 x86_pmu_current_partition_mask(void);
 
 #ifdef CONFIG_CPU_SUP_INTEL
-- 
2.55.0