[PATCH v9 19/22] KVM: arm64: Detect overflows for the Partitioned PMU

[Colton Lewis]

When re-entering the VM or synchronizing PMU state after a guest counter
overflow interrupt, evaluate whether any enabled and unmasked guest
counter has overflowed ((PMOVSSET_EL0 & PMINTENSET_EL1 & PMCNTENSET_EL0)
with PMCR_EL0.E set) and update the virtual PMU interrupt level in the
vGIC accordingly.

Signed-off-by: Colton Lewis <coltonlewis at google.com>
---
 arch/arm64/kvm/pmu-direct.c | 55 +++++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/pmu-emul.c   | 12 ++++++--
 arch/arm64/kvm/pmu.c        |  8 +++++-
 include/kvm/arm_pmu.h       |  2 ++
 4 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/pmu-direct.c b/arch/arm64/kvm/pmu-direct.c
index 95b5a64052762..ec821aa54688f 100644
--- a/arch/arm64/kvm/pmu-direct.c
+++ b/arch/arm64/kvm/pmu-direct.c
@@ -534,6 +534,61 @@ void kvm_pmu_handle_guest_irq(u64 pmovsr)
 
 	for_each_set_bit(i, (unsigned long *)&govf, 64)
 		set_bit(i, (unsigned long *)__ctxt_sys_reg(&vcpu->arch.ctxt, PMOVSSET_EL0));
+
+	if (kvm_pmu_part_overflow_status(vcpu)) {
+		kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
+
+		if (!in_nmi())
+			kvm_vcpu_kick(vcpu);
+		else
+			irq_work_queue(&vcpu->arch.pmu.overflow_work);
+	}
+}
+
+/**
+ * kvm_pmu_part_overflow_status() - Determine if any guest counters have overflowed
+ * @vcpu: Pointer to struct kvm_vcpu
+ *
+ * Determine if any guest counters have overflowed and therefore an
+ * IRQ needs to be injected into the guest. If an overflow is detected
+ * while access is VCPU_PMU_ACCESS_FREE (for example, after state
+ * restoration via KVM_SET_ONE_REG), transition the vCPU to
+ * VCPU_PMU_ACCESS_GUEST_OWNED.
+ *
+ * Return: True if there was an overflow, false otherwise
+ */
+bool kvm_pmu_part_overflow_status(struct kvm_vcpu *vcpu)
+{
+	u64 mask = kvm_vcpu_pmu_guest_counter_mask(vcpu);
+	u64 pmovs, pmint, pmcr;
+	unsigned long flags;
+	bool overflow;
+
+	local_irq_save(flags);
+	if (vcpu->arch.pmu.loaded_on_cpu &&
+	    vcpu == kvm_get_running_vcpu()) {
+		u64 hw_ovf = read_sysreg(pmovsset_el0) & mask;
+
+		if (hw_ovf) {
+			__vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, hw_ovf);
+			write_sysreg(hw_ovf, pmovsclr_el0);
+		}
+		pmint = read_pmintenset();
+		pmcr = read_pmcr();
+	} else {
+		pmint = __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
+		pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
+	}
+
+	pmovs = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
+	local_irq_restore(flags);
+
+	overflow = (pmcr & ARMV8_PMU_PMCR_E) && (mask & pmovs & pmint);
+
+	if (overflow && kvm_pmu_get_access(vcpu) == VCPU_PMU_ACCESS_FREE)
+		kvm_pmu_set_guest_owned(vcpu);
+
+	return overflow;
 }
 
 /**
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index e8195984b0373..21e2c96abfdb1 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -268,7 +268,7 @@ void kvm_pmu_reprogram_counter_mask(struct kvm_vcpu *vcpu, u64 val)
  * counter where the values of the global enable control, PMOVSSET_EL0[n], and
  * PMINTENSET_EL1[n] are all 1.
  */
-bool kvm_pmu_overflow_status(struct kvm_vcpu *vcpu)
+bool kvm_pmu_emul_overflow_status(struct kvm_vcpu *vcpu)
 {
 	u64 reg = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
 
@@ -296,8 +296,14 @@ bool kvm_pmu_should_notify_user(struct kvm_vcpu *vcpu)
 {
 	struct kvm_sync_regs *sregs = &vcpu->run->s.regs;
 	bool run_level = sregs->device_irq_level & KVM_ARM_DEV_PMU;
+	bool overflow;
 
-	return kvm_pmu_overflow_status(vcpu) != run_level;
+	if (kvm_pmu_is_partitioned(vcpu->kvm))
+		overflow = kvm_pmu_part_overflow_status(vcpu);
+	else
+		overflow = kvm_pmu_emul_overflow_status(vcpu);
+
+	return overflow != run_level;
 }
 
 /*
@@ -400,7 +406,7 @@ static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
 		kvm_pmu_counter_increment(vcpu, BIT(idx + 1),
 					  ARMV8_PMUV3_PERFCTR_CHAIN);
 
-	if (kvm_pmu_overflow_status(vcpu)) {
+	if (kvm_pmu_emul_overflow_status(vcpu)) {
 		kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
 
 		if (!in_nmi())
diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
index a8214ab52fcb5..4a3c6600b2678 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -409,12 +409,18 @@ u64 kvm_pmu_evtyper_mask(struct kvm *kvm)
 static void kvm_pmu_update_state(struct kvm_vcpu *vcpu)
 {
 	struct kvm_pmu *pmu = &vcpu->arch.pmu;
+	bool overflow;
 
 	if (unlikely(!irqchip_in_kernel(vcpu->kvm)))
 		return;
 
+	if (kvm_pmu_is_partitioned(vcpu->kvm))
+		overflow = kvm_pmu_part_overflow_status(vcpu);
+	else
+		overflow = kvm_pmu_emul_overflow_status(vcpu);
+
 	WARN_ON(kvm_vgic_inject_irq(vcpu->kvm, vcpu, pmu->irq_num,
-				    kvm_pmu_overflow_status(vcpu), pmu));
+				    overflow, pmu));
 }
 
 /**
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 955f142a41b94..428a609eaf1a7 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -91,6 +91,8 @@ bool kvm_set_pmuserenr(u64 val);
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
 void kvm_vcpu_pmu_resync_el0(void);
+bool kvm_pmu_emul_overflow_status(struct kvm_vcpu *vcpu);
+bool kvm_pmu_part_overflow_status(struct kvm_vcpu *vcpu);
 
 #define kvm_vcpu_has_pmu(vcpu)					\
 	(vcpu_has_feature(vcpu, KVM_ARM_VCPU_PMU_V3))
-- 
2.56.0.rc1.310.g51773c2048-goog