KVM: arm64: Add PMU event filter bits required if EL3 is implemented

Suzuki noticed that KVM's PMU emulation is oblivious to the NSU and NSK
event filter bits. On systems that have EL3 these bits modify the
filter behavior in non-secure EL0 and EL1, respectively. Even though the
kernel doesn't use these bits, it is entirely possible some other guest
OS does. Additionally, it would appear that these and the M bit are
required by the architecture if EL3 is implemented.

Allow the EL3 event filter bits to be set if EL3 is advertised in the
guest's ID register. Implement the behavior of NSU and NSK according to
the pseudocode, and entirely ignore the M bit for perf event creation.

Reported-by: Suzuki K Poulose <[email protected]>
Reviewed-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Oliver Upton <[email protected]>

Author: oupton

arch/arm64/kvm/pmu-emul.c

@@ -69,6 +69,11 @@ u64 kvm_pmu_evtyper_mask(struct kvm *kvm)
 	if (SYS_FIELD_GET(ID_AA64PFR0_EL1, EL2, pfr0))
 		mask |= ARMV8_PMU_INCLUDE_EL2;
 
+	if (SYS_FIELD_GET(ID_AA64PFR0_EL1, EL3, pfr0))
+		mask |= ARMV8_PMU_EXCLUDE_NS_EL0 |
+			ARMV8_PMU_EXCLUDE_NS_EL1 |
+			ARMV8_PMU_EXCLUDE_EL3;
+
 	return mask;
 }
 
@@ -596,6 +601,7 @@ static void kvm_pmu_create_perf_event(struct kvm_pmc *pmc)
 	struct perf_event *event;
 	struct perf_event_attr attr;
 	u64 eventsel, reg, data;
+	bool p, u, nsk, nsu;
 
 	reg = counter_index_to_evtreg(pmc->idx);
 	data = __vcpu_sys_reg(vcpu, reg);
@@ -622,13 +628,18 @@ static void kvm_pmu_create_perf_event(struct kvm_pmc *pmc)
 	    !test_bit(eventsel, vcpu->kvm->arch.pmu_filter))
 		return;
 
+	p = data & ARMV8_PMU_EXCLUDE_EL1;
+	u = data & ARMV8_PMU_EXCLUDE_EL0;
+	nsk = data & ARMV8_PMU_EXCLUDE_NS_EL1;
+	nsu = data & ARMV8_PMU_EXCLUDE_NS_EL0;
+
 	memset(&attr, 0, sizeof(struct perf_event_attr));
 	attr.type = arm_pmu->pmu.type;
 	attr.size = sizeof(attr);
 	attr.pinned = 1;
 	attr.disabled = !kvm_pmu_counter_is_enabled(pmc);
-	attr.exclude_user = data & ARMV8_PMU_EXCLUDE_EL0 ? 1 : 0;
-	attr.exclude_kernel = data & ARMV8_PMU_EXCLUDE_EL1 ? 1 : 0;
+	attr.exclude_user = (u != nsu);
+	attr.exclude_kernel = (p != nsk);
 	attr.exclude_hv = 1; /* Don't count EL2 events */
 	attr.exclude_host = 1; /* Don't count host events */
 	attr.config = eventsel;

include/linux/perf/arm_pmuv3.h

@@ -234,9 +234,12 @@
 /*
  * Event filters for PMUv3
  */
-#define ARMV8_PMU_EXCLUDE_EL1	(1U << 31)
-#define ARMV8_PMU_EXCLUDE_EL0	(1U << 30)
-#define ARMV8_PMU_INCLUDE_EL2	(1U << 27)
+#define ARMV8_PMU_EXCLUDE_EL1		(1U << 31)
+#define ARMV8_PMU_EXCLUDE_EL0		(1U << 30)
+#define ARMV8_PMU_EXCLUDE_NS_EL1	(1U << 29)
+#define ARMV8_PMU_EXCLUDE_NS_EL0	(1U << 28)
+#define ARMV8_PMU_INCLUDE_EL2		(1U << 27)
+#define ARMV8_PMU_EXCLUDE_EL3		(1U << 26)
 
 /*
  * PMUSERENR: user enable reg