linux-kernel - [PATCH v12 32/46] arm64: RMI: Allow checking SVE on VM instance

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Message-ID: <20251217101125.91098-33-steven.price@arm.com>
Date: Wed, 17 Dec 2025 10:11:09 +0000
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Suzuki K Poulose <suzuki.poulose@....com>,
	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>,
	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>,
	Emi Kisanuki <fj0570is@...itsu.com>,
	Vishal Annapurve <vannapurve@...gle.com>,
	Steven Price <steven.price@....com>
Subject: [PATCH v12 32/46] arm64: RMI: Allow checking SVE on VM instance

From: Suzuki K Poulose <suzuki.poulose@....com>

Given we have different types of VMs supported, check the
support for SVE for the given instance of the VM to accurately
report the status.

Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
Signed-off-by: Steven Price <steven.price@....com>
Reviewed-by: Gavin Shan <gshan@...hat.com>
Reviewed-by: Joey Gouly <joey.gouly@....com>
---
Changes since v10:
 * RME->RMI renaming.
 * Adapt to move CAP check to kvm_realm_ext_allowed().
---
 arch/arm64/include/asm/kvm_rmi.h |  2 ++
 arch/arm64/kvm/arm.c             |  2 ++
 arch/arm64/kvm/rmi.c             | 10 ++++++++++
 3 files changed, 14 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h
index 77da297ca09d..82280c138935 100644
--- a/arch/arm64/include/asm/kvm_rmi.h
+++ b/arch/arm64/include/asm/kvm_rmi.h
@@ -89,6 +89,8 @@ void kvm_init_rmi(void);
 u32 kvm_realm_ipa_limit(void);
 u32 kvm_realm_vgic_nr_lr(void);
 
+bool kvm_rmi_supports_sve(void);
+
 int kvm_init_realm_vm(struct kvm *kvm);
 int kvm_activate_realm(struct kvm *kvm);
 void kvm_destroy_realm(struct kvm *kvm);
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 403f9119543e..f8255de92902 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -342,6 +342,8 @@ static bool kvm_realm_ext_allowed(long ext)
 	case KVM_CAP_ARM_PTRAUTH_GENERIC:
 	case KVM_CAP_ARM_RMI:
 		return true;
+	case KVM_CAP_ARM_SVE:
+		return kvm_rmi_supports_sve();
 	}
 	return false;
 }
diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
index 5f50566c701d..7ef5d7f48d0b 100644
--- a/arch/arm64/kvm/rmi.c
+++ b/arch/arm64/kvm/rmi.c
@@ -33,6 +33,16 @@ static inline unsigned long rmi_rtt_level_mapsize(int level)
 	return (1UL << RMM_RTT_LEVEL_SHIFT(level));
 }
 
+static bool rmi_has_feature(unsigned long feature)
+{
+	return !!u64_get_bits(rmm_feat_reg0, feature);
+}
+
+bool kvm_rmi_supports_sve(void)
+{
+	return rmi_has_feature(RMI_FEATURE_REGISTER_0_SVE_EN);
+}
+
 static int rmi_check_version(void)
 {
 	struct arm_smccc_res res;
-- 
2.43.0