[PATCH v5 21/24] KVM: arm64: Inject recorded guest interrupts

Colton Lewis
2025-12-09T20:52:54Z

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@google.com>
---
arch/arm64/include/asm/kvm_pmu.h | 2 ++
arch/arm64/kvm/pmu-direct.c | 20 ++++++++++++++++++++
arch/arm64/kvm/pmu-emul.c | 4 ++--
arch/arm64/kvm/pmu.c | 6 +++++-
4 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_pmu.h b/arch/arm64/include/asm/kvm_pmu.h
index e4cbab0fd09cf..47e6f2a14e381 100644
--- a/arch/arm64/include/asm/kvm_pmu.h
+++ b/arch/arm64/include/asm/kvm_pmu.h
@@ -92,6 +92,8 @@ bool pmu_counter_idx_valid(struct kvm_vcpu *vcpu, u64 idx);
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))
diff --git a/arch/arm64/kvm/pmu-direct.c b/arch/arm64/kvm/pmu-direct.c
index 76d8ed24c8646..2ee99d6d2b6c1 100644
--- a/arch/arm64/kvm/pmu-direct.c
+++ b/arch/arm64/kvm/pmu-direct.c
@@ -413,3 +413,23 @@ void kvm_pmu_handle_guest_irq(u64 govf)

__vcpu_rmw_sys_reg(vcpu, PMOVSSET_EL0, |=, govf);
}
+
+/**
+ * kvm_pmu_part_overflow_status() - Determine if any guest counters have overflowed
+ * @vcpu: Ponter to struct kvm_vcpu
+ *
+ * Determine if any guest counters have overflowed and therefore an
+ * IRQ needs to be injected into the guest.
+ *
+ * Return: True if there was an overflow, false otherwise
+ */
+bool kvm_pmu_part_overflow_status(struct kvm_vcpu *vcpu)
+{
+ struct arm_pmu *pmu = vcpu->kvm->arch.arm_pmu;
+ u64 mask = kvm_pmu_guest_counter_mask(pmu);
+ u64 pmovs = __vcpu_sys_reg(vcpu, PMOVSSET_EL0);
+ u64 pmint = read_pmintenset();
+ u64 pmcr = read_pmcr();
+
+ return (pmcr & ARMV8_PMU_PMCR_E) && (mask & pmovs & pmint);
+}
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index bcaa9f7a8ca28..6f41fc3e3f74b 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 c9862e55a4049..e1332a158dfc8 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -407,7 +407,11 @@ 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_vcpu_pmu_is_partitioned(vcpu))
+ overflow = kvm_pmu_part_overflow_status(vcpu);
+ else
+ overflow = kvm_pmu_emul_overflow_status(vcpu);
+
if (pmu->irq_level == overflow)
return;

--
2.52.0.239.gd5f0c6e74e-goog