linux-kernel - [PATCH 15/17] KVM: arm64: Inject recorded guest interrupts

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Message-ID: <20250602192702.2125115-16-coltonlewis@google.com>
Date: Mon,  2 Jun 2025 19:27:00 +0000
From: Colton Lewis <coltonlewis@...gle.com>
To: kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jonathan Corbet <corbet@....net>, 
	Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Mark Rutland <mark.rutland@....com>, 
	Shuah Khan <shuah@...nel.org>, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	linux-perf-users@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	Colton Lewis <coltonlewis@...gle.com>
Subject: [PATCH 15/17] KVM: arm64: Inject recorded guest interrupts

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@...gle.com>
---
 arch/arm64/include/asm/kvm_host.h |  3 ++-
 arch/arm64/kvm/pmu-emul.c         |  4 ++--
 arch/arm64/kvm/pmu-part.c         | 22 +++++++++++++++++++++-
 arch/arm64/kvm/pmu.c              |  7 ++++++-
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 955359f20161..0af8cc4c340f 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -1714,9 +1714,10 @@ bool kvm_vcpu_pmu_is_partitioned(struct kvm_vcpu *vcpu);
 struct kvm_pmu_events *kvm_get_pmu_events(void);
 void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu);
 void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
-bool kvm_pmu_overflow_status(struct kvm_vcpu *vcpu);
+bool kvm_pmu_emul_overflow_status(struct kvm_vcpu *vcpu);
 void kvm_pmu_load(struct kvm_vcpu *vcpu);
 void kvm_pmu_put(struct kvm_vcpu *vcpu);
+bool kvm_pmu_part_overflow_status(struct kvm_vcpu *vcpu);
 
 /*
  * Updates the vcpu's view of the pmu events for this cpu.
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index ff86c66e1b48..0ffabada1dad 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -320,7 +320,7 @@ 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);
 
@@ -457,7 +457,7 @@ 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-part.c b/arch/arm64/kvm/pmu-part.c
index 0e1a2235e992..1d85e7ce76c8 100644
--- a/arch/arm64/kvm/pmu-part.c
+++ b/arch/arm64/kvm/pmu-part.c
@@ -252,7 +252,7 @@ void kvm_pmu_load(struct kvm_vcpu *vcpu)
 	write_pmcr(val);
 
 	/*
-	 * Loading these registers is tricky because of
+	 * Loading these registers is more intricate because of
 	 * 1. Applying only the bits for guest counters (indicated by mask)
 	 * 2. Setting and clearing are different registers
 	 */
@@ -336,3 +336,23 @@ void kvm_pmu_handle_guest_irq(u64 govf)
 
 	__vcpu_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.c b/arch/arm64/kvm/pmu.c
index 2dcfac3ea9c6..6c3151dec25a 100644
--- a/arch/arm64/kvm/pmu.c
+++ b/arch/arm64/kvm/pmu.c
@@ -425,7 +425,11 @@ 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;
 
@@ -694,6 +698,7 @@ int kvm_arm_pmu_v3_set_attr(struct kvm_vcpu *vcpu, struct kvm_device_attr *attr)
 			return -EBUSY;
 
 		kvm_debug("Set kvm ARM PMU irq: %d\n", irq);
+
 		vcpu->arch.pmu.irq_num = irq;
 		return 0;
 	}
-- 
2.49.0.1204.g71687c7c1d-goog