[PATCH 17/21] KVM: arm64: Detect overflows for the Partitioned PMU

[Colton Lewis]

When we re-enter the VM after handling a PMU interrupt, calculate
whether it was any of the guest counters that overflowed and inject an
interrupt into the guest if so.

Signed-off-by: Colton Lewis <coltonlewis at google.com>
---
 arch/arm64/kvm/pmu-direct.c | 48 +++++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/pmu-emul.c   |  4 ++--
 arch/arm64/kvm/pmu.c        |  6 ++++-
 include/kvm/arm_pmu.h       |  2 ++
 4 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/pmu-direct.c b/arch/arm64/kvm/pmu-direct.c
index 64f40cfb31012..0062d1d8e1999 100644
--- a/arch/arm64/kvm/pmu-direct.c
+++ b/arch/arm64/kvm/pmu-direct.c
@@ -426,4 +426,52 @@ void kvm_pmu_handle_guest_irq(struct arm_pmu *pmu, u64 pmovsr)
 		return;
 
 	__vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, govf);
+
+	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 access is still free,
+ * then the guest hasn't accessed the PMU yet so we know the guest
+ * context is not loaded onto the pCPU and an overflow is impossible.
+ *
+ * Return: True if there was an overflow, false otherwise
+ */
+bool kvm_pmu_part_overflow_status(struct kvm_vcpu *vcpu)
+{
+	struct arm_pmu *pmu;
+	u64 mask, pmovs, pmint, pmcr;
+	bool overflow;
+
+	pmu = vcpu->kvm->arch.arm_pmu;
+	mask = kvm_pmu_guest_counter_mask(pmu);
+
+	if (vcpu->arch.pmu.access == VCPU_PMU_ACCESS_FREE) {
+		pmovs = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
+		pmint = __vcpu_sys_reg(vcpu, PMINTENSET_EL1);
+		pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
+
+		if ((pmcr & ARMV8_PMU_PMCR_E) && (mask & pmovs & pmint))
+			kvm_pmu_set_guest_owned(vcpu);
+		else
+			return false;
+	}
+
+	pmovs = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
+	pmint = read_pmintenset();
+	pmcr = read_pmcr();
+	overflow = (pmcr & ARMV8_PMU_PMCR_E) && (mask & pmovs & pmint);
+
+	return overflow;
 }
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index d1110febe7436..ebc68090bdb26 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);
 
@@ -405,7 +405,7 @@ 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 55cda8021400a..f5ee18b4dfae7 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -409,7 +409,11 @@ static void kvm_pmu_update_state(struct kvm_vcpu *vcpu)
 	struct kvm_pmu *pmu = &vcpu->arch.pmu;
 	bool overflow;
 
-	overflow = kvm_pmu_overflow_status(vcpu);
+	if (kvm_pmu_is_partitioned(vcpu->kvm))
+		overflow = kvm_pmu_part_overflow_status(vcpu);
+	else
+		overflow = kvm_pmu_emul_overflow_status(vcpu);
+
 	if (pmu->irq_level == overflow)
 		return;
 
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 25163a689ae80..f72d080ee7ba2 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -93,6 +93,8 @@ 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))
-- 
2.54.0.1136.gdb2ca164c4-goog