linux-kernel - [PATCH v2 38/43] arm64: RME: Propagate max SVE vector length from RMM

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Message-Id: <20240412084309.1733783-39-steven.price@arm.com>
Date: Fri, 12 Apr 2024 09:43:04 +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>,
	Steven Price <steven.price@....com>
Subject: [PATCH v2 38/43] arm64: RME: Propagate max SVE vector length from RMM

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

RMM provides the maximum vector length it supports for a guest in its
feature register. Make it visible to the rest of KVM and to userspace
via KVM_REG_ARM64_SVE_VLS.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
Signed-off-by: Steven Price <steven.price@....com>
---
 arch/arm64/include/asm/kvm_host.h |  2 +-
 arch/arm64/include/asm/kvm_rme.h  |  1 +
 arch/arm64/kvm/guest.c            |  2 +-
 arch/arm64/kvm/reset.c            | 12 ++++++++++--
 arch/arm64/kvm/rme.c              |  6 ++++++
 5 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f7ac40ce0caf..902923402f6e 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -76,8 +76,8 @@ static inline enum kvm_mode kvm_get_mode(void) { return KVM_MODE_NONE; };
 
 DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use);
 
-extern unsigned int __ro_after_init kvm_sve_max_vl;
 int __init kvm_arm_init_sve(void);
+unsigned int kvm_sve_get_max_vl(struct kvm *kvm);
 
 u32 __attribute_const__ kvm_target_cpu(void);
 void kvm_reset_vcpu(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
index 9c00bcb018f8..be24be001aaa 100644
--- a/arch/arm64/include/asm/kvm_rme.h
+++ b/arch/arm64/include/asm/kvm_rme.h
@@ -89,6 +89,7 @@ struct realm_rec {
 int kvm_init_rme(void);
 u32 kvm_realm_ipa_limit(void);
 u8 kvm_realm_max_pmu_counters(void);
+unsigned int kvm_realm_sve_max_vl(void);
 u64 kvm_realm_reset_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, u64 val);
 
 bool kvm_rme_supports_sve(void);
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index f9a47ce71a26..c62fda66cdc5 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -355,7 +355,7 @@ static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 		if (vq_present(vqs, vq))
 			max_vq = vq;
 
-	if (max_vq > sve_vq_from_vl(kvm_sve_max_vl))
+	if (max_vq > sve_vq_from_vl(kvm_sve_get_max_vl(vcpu->kvm)))
 		return -EINVAL;
 
 	/*
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 6e6eb4a15095..a90b7c2d35bb 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -45,7 +45,7 @@ static u32 __ro_after_init kvm_ipa_limit;
 #define VCPU_RESET_PSTATE_SVC	(PSR_AA32_MODE_SVC | PSR_AA32_A_BIT | \
 				 PSR_AA32_I_BIT | PSR_AA32_F_BIT)
 
-unsigned int __ro_after_init kvm_sve_max_vl;
+static unsigned int __ro_after_init kvm_sve_max_vl;
 
 int __init kvm_arm_init_sve(void)
 {
@@ -73,9 +73,17 @@ int __init kvm_arm_init_sve(void)
 	return 0;
 }
 
+unsigned int kvm_sve_get_max_vl(struct kvm *kvm)
+{
+	if (kvm_is_realm(kvm))
+		return kvm_realm_sve_max_vl();
+	else
+		return kvm_sve_max_vl;
+}
+
 static void kvm_vcpu_enable_sve(struct kvm_vcpu *vcpu)
 {
-	vcpu->arch.sve_max_vl = kvm_sve_max_vl;
+	vcpu->arch.sve_max_vl = kvm_sve_get_max_vl(vcpu->kvm);
 
 	/*
 	 * Userspace can still customize the vector lengths by writing
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index 1bd97e206846..cd5b74aac092 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -276,6 +276,12 @@ u8 kvm_realm_max_pmu_counters(void)
 	return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_PMU_NUM_CTRS);
 }
 
+unsigned int kvm_realm_sve_max_vl(void)
+{
+	return sve_vl_from_vq(u64_get_bits(rmm_feat_reg0,
+					   RMI_FEATURE_REGISTER_0_SVE_VL) + 1);
+}
+
 u64 kvm_realm_reset_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, u64 val)
 {
 	u32 bps = u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_NUM_BPS);
-- 
2.34.1