From 4eb776d0b98436c726db2d0066f253d98c2758d2 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 30 Jul 2026 08:10:04 +0100 Subject: [PATCH] KVM: arm64: Expose FEAT_NV2p1 to NV guests Since NV2p1 is reducing the number of traps, it is valuable to expose it to NV guests. Do so. Reviewed-by: Yuan Yao Signed-off-by: Marc Zyngier Link: https://patch.msgid.link/20260730071022.296811-12-maz@kernel.org Signed-off-by: Oliver Upton --- arch/arm64/kvm/nested.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index fb54f6dad995..82be8bcb0703 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -1726,7 +1726,7 @@ u64 limit_nv_id_reg(struct kvm *kvm, u32 reg, u64 val) * You get EITHER * * - FEAT_VHE without FEAT_E2H0 - * - FEAT_NV limited to FEAT_NV2 + * - FEAT_NV limited to FEAT_NV2(p1) * - HCR_EL2.NV1 being RES0 * * OR @@ -1738,7 +1738,11 @@ u64 limit_nv_id_reg(struct kvm *kvm, u32 reg, u64 val) if (test_bit(KVM_ARM_VCPU_HAS_EL2_E2H0, kvm->arch.vcpu_features)) { val = 0; } else { - val = SYS_FIELD_PREP_ENUM(ID_AA64MMFR4_EL1, NV_frac, NV2_ONLY); + val &= ID_AA64MMFR4_EL1_NV_frac; + if (cpus_have_final_cap(ARM64_HAS_NV2P1)) + val = ID_REG_LIMIT_FIELD_ENUM(val, ID_AA64MMFR4_EL1, NV_frac, NV2P1); + else + val = SYS_FIELD_PREP_ENUM(ID_AA64MMFR4_EL1, NV_frac, NV2_ONLY); val |= SYS_FIELD_PREP_ENUM(ID_AA64MMFR4_EL1, E2H0, NI_NV1); } break;