[PATCH 07/23] perf/x86: Apply PMU partition mask on static constraints

[Zide Chen]

Static, counter-specific constraints used for attr.precise_ip == 3, or
other special cases bypass intel_get_event_constraints(), which is
where partition_mask is applied via dyn_constraint().

As a result, such a host !exclude_guest event can still be scheduled
onto a counter that partition_mask reserves for the guest, causing
host and guest to share the same hardware counter.

Some of these static constraint paths, e.g. glp or cmt, are currently
only reachable on platforms that don't support PerfMon masking. Still,
apply part_constraint() to all of them uniformly, so future platforms
that combine PerfMon masking with these constraint paths are not
silently exposed to this bug.

Signed-off-by: Zide Chen <zide.chen@xxxxxxxxx>
---
 arch/x86/events/intel/core.c | 39 +++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 7951accfcf2c..0f76e56fd2db 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4459,6 +4459,9 @@ dyn_constraint(struct cpu_hw_events *cpuc, struct event_constraint *c, int idx)
  * Mask out guest-owned counters from a constraint when PMU partition has been
  * entered, so !exclude_guest host events are not scheduled onto them while
  * the CPU is in non-root mode.
+ *
+ * This is also used by PMU-specific get_event_constraints() wrappers
+ * that hard-code a static, counter-specific constraint.
  */
 static struct event_constraint *
 part_constraint(struct cpu_hw_events *cpuc, int idx,
@@ -5568,7 +5571,7 @@ hsw_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 	/* Handle special quirk on in_tx_checkpointed only in counter 2 */
 	if (event->hw.config & HSW_IN_TX_CHECKPOINTED) {
 		if (c->idxmsk64 & (1U << 2))
-			return &counter2_constraint;
+			return part_constraint(cpuc, idx, event, &counter2_constraint);
 		return &emptyconstraint;
 	}
 
@@ -5585,7 +5588,7 @@ icl_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 	 */
 	if ((event->attr.precise_ip == 3) &&
 	    constraint_match(&fixed0_constraint, event->hw.config))
-		return &fixed0_constraint;
+		return part_constraint(cpuc, idx, event, &fixed0_constraint);
 
 	return hsw_get_event_constraints(cpuc, idx, event);
 }
@@ -5607,7 +5610,7 @@ glc_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 	if ((event->attr.precise_ip == 3) &&
 	    !constraint_match(&fixed0_constraint, event->hw.config)) {
 		if (c->idxmsk64 & BIT_ULL(0))
-			return &counter0_constraint;
+			return part_constraint(cpuc, idx, event, &counter0_constraint);
 
 		return &emptyconstraint;
 	}
@@ -5623,7 +5626,7 @@ glp_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 
 	/* :ppp means to do reduced skid PEBS which is PMC0 only. */
 	if (event->attr.precise_ip == 3)
-		return &counter0_constraint;
+		return part_constraint(cpuc, idx, event, &counter0_constraint);
 
 	c = intel_get_event_constraints(cpuc, idx, event);
 
@@ -5645,9 +5648,9 @@ tnt_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 	if (event->attr.precise_ip == 3) {
 		/* Force instruction:ppp on PMC0 and Fixed counter 0 */
 		if (constraint_match(&fixed0_constraint, event->hw.config))
-			return &fixed0_counter0_constraint;
+			return part_constraint(cpuc, idx, event, &fixed0_counter0_constraint);
 
-		return &counter0_constraint;
+		return part_constraint(cpuc, idx, event, &counter0_constraint);
 	}
 
 	return c;
@@ -5705,22 +5708,30 @@ cmt_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 	if (event->attr.precise_ip == 3) {
 		/* Force instruction:ppp on PMC0, 1 and Fixed counter 0 */
 		if (constraint_match(&fixed0_constraint, event->hw.config)) {
+			c = &fixed0_counter0_1_constraint;
+
 			/* The fixed counter 0 doesn't support LBR event logging. */
 			if (branch_sample_counters(event))
-				return &counter0_1_constraint;
-			else
-				return &fixed0_counter0_1_constraint;
+				c = &counter0_1_constraint;
+
+			return part_constraint(cpuc, idx, event, c);
 		}
 
 		switch (c->idxmsk64 & 0x3ull) {
 		case 0x1:
-			return &counter0_constraint;
+			c = &counter0_constraint;
+			break;
 		case 0x2:
-			return &counter1_constraint;
+			c = &counter1_constraint;
+			break;
 		case 0x3:
-			return &counter0_1_constraint;
+			c = &counter0_1_constraint;
+			break;
+		default:
+			c = &emptyconstraint;
+			break;
 		}
-		return &emptyconstraint;
+		return part_constraint(cpuc, idx, event, c);
 	}
 
 	return c;
@@ -5744,7 +5755,7 @@ rwc_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 		 */
 		if (event->attr.precise_ip == 3)
 			return &emptyconstraint;
-		return &counters_1_7_constraint;
+		return part_constraint(cpuc, idx, event, &counters_1_7_constraint);
 	}
 
 	return c;
-- 
2.55.0