linux-kernel - [PATCH v8 36/43] arm64: RME: Initialize PMCR.N with number counter supported by RMM

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Message-ID: <20250416134208.383984-37-steven.price@arm.com>
Date: Wed, 16 Apr 2025 14:41:58 +0100
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>,
	linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@...nel.org>,
	Steven Price <steven.price@....com>
Subject: [PATCH v8 36/43] arm64: RME: Initialize PMCR.N with number counter supported by RMM

From: Jean-Philippe Brucker <jean-philippe@...aro.org>

Provide an accurate number of available PMU counters to userspace when
setting up a Realm.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/include/asm/kvm_rme.h | 1 +
 arch/arm64/kvm/pmu-emul.c        | 3 +++
 arch/arm64/kvm/rme.c             | 5 +++++
 3 files changed, 9 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
index 09cbb61816f3..773e730da364 100644
--- a/arch/arm64/include/asm/kvm_rme.h
+++ b/arch/arm64/include/asm/kvm_rme.h
@@ -93,6 +93,7 @@ struct realm_rec {
 void kvm_init_rme(void);
 u32 kvm_realm_ipa_limit(void);
 u32 kvm_realm_vgic_nr_lr(void);
+u8 kvm_realm_max_pmu_counters(void);
 
 u64 kvm_realm_reset_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, u64 val);
 
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 52b6e0eda894..5ca2eac730b3 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -1016,6 +1016,9 @@ u8 kvm_arm_pmu_get_max_counters(struct kvm *kvm)
 {
 	struct arm_pmu *arm_pmu = kvm->arch.arm_pmu;
 
+	if (kvm_is_realm(kvm))
+		return kvm_realm_max_pmu_counters();
+
 	/*
 	 * PMUv3 requires that all event counters are capable of counting any
 	 * event, though the same may not be true of non-PMUv3 hardware.
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index 7e5469ae8a95..b09faca304fe 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -87,6 +87,11 @@ u32 kvm_realm_vgic_nr_lr(void)
 	return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_GICV3_NUM_LRS);
 }
 
+u8 kvm_realm_max_pmu_counters(void)
+{
+	return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_PMU_NUM_CTRS);
+}
+
 u64 kvm_realm_reset_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, u64 val)
 {
 	u32 bps = u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_NUM_BPS);
-- 
2.43.0