[RFC PATCH v3 01/10] KVM: arm64: RMI: Add and export kvm_has_da_feature helper

Aneesh Kumar K.V (Arm)
2026-03-12T08:01:59Z

Add kvm_has_da_feature() helper for use in later patches.
Update reserved fields based on Alp17 spec.

Cc: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Alexey Kardashevskiy <aik@amd.com>
Cc: Samuel Ortiz <sameo@rivosinc.com>
Cc: Xu Yilun <yilun.xu@linux.intel.com>
Cc: Suzuki K Poulose <Suzuki.Poulose@arm.com>
Cc: Steven Price <steven.price@arm.com>
Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
arch/arm64/include/asm/kvm_rmi.h | 1 +
arch/arm64/include/asm/rmi_smc.h | 3 ++-
arch/arm64/kvm/rmi.c | 6 ++++++
3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/kvm_rmi.h b/arch/arm64/include/asm/kvm_rmi.h
index 1b2cdaac6c50..a967061af6ed 100644
--- a/arch/arm64/include/asm/kvm_rmi.h
+++ b/arch/arm64/include/asm/kvm_rmi.h
@@ -90,6 +90,7 @@ u32 kvm_realm_ipa_limit(void);
u32 kvm_realm_vgic_nr_lr(void);
u8 kvm_realm_max_pmu_counters(void);
unsigned int kvm_realm_sve_max_vl(void);
+bool kvm_has_da_feature(void);

u64 kvm_realm_reset_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, u64 val);

diff --git a/arch/arm64/include/asm/rmi_smc.h b/arch/arm64/include/asm/rmi_smc.h
index 1000368f1bca..f6f786bfb9c9 100644
--- a/arch/arm64/include/asm/rmi_smc.h
+++ b/arch/arm64/include/asm/rmi_smc.h
@@ -86,7 +86,8 @@ enum rmi_ripas {
#define RMI_FEATURE_REGISTER_0_HASH_SHA_512 BIT(33)
#define RMI_FEATURE_REGISTER_0_GICV3_NUM_LRS GENMASK(37, 34)
#define RMI_FEATURE_REGISTER_0_MAX_RECS_ORDER GENMASK(41, 38)
-#define RMI_FEATURE_REGISTER_0_Reserved GENMASK(63, 42)
+#define RMI_FEATURE_REGISTER_0_DA BIT(42)
+#define RMI_FEATURE_REGISTER_0_Reserved GENMASK(63, 61)

#define RMI_REALM_PARAM_FLAG_LPA2 BIT(0)
#define RMI_REALM_PARAM_FLAG_SVE BIT(1)
diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
index 478a73e0b35a..08f3d2362dfd 100644
--- a/arch/arm64/kvm/rmi.c
+++ b/arch/arm64/kvm/rmi.c
@@ -1738,6 +1738,12 @@ int kvm_init_realm_vm(struct kvm *kvm)
return 0;
}

+bool kvm_has_da_feature(void)
+{
+ return rmi_has_feature(RMI_FEATURE_REGISTER_0_DA);
+}
+EXPORT_SYMBOL_GPL(kvm_has_da_feature);
+
void kvm_init_rmi(void)
{
/* Only 4k page size on the host is supported */
--
2.43.0