From 3b3ae6bfaca0ca2ec82cde9f21fc7e4cb4ed4b9a Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 30 Jul 2026 08:10:13 +0100 Subject: [PATCH] KVM: arm64: Add sanitisation for NVHCR_EL2 Just like any other VNCR-based register, NVHCR_EL2 requires some level of sanitisation. Being specified as a live copy of HCR_EL2, it adopts the exact same format, but depends on FEAT_NV3 instead. A subtle aspect is that we only want to apply the sanitisation if FEAT_NV3 is actually present, as the VNCR location is otherwise used to back accesses to HCR_EL2. Reviewed-by: Yuan Yao Signed-off-by: Marc Zyngier Link: https://patch.msgid.link/20260730071022.296811-21-maz@kernel.org Signed-off-by: Oliver Upton --- arch/arm64/kvm/config.c | 15 +++++++++++++++ arch/arm64/kvm/nested.c | 4 ++++ 2 files changed, 19 insertions(+) diff --git a/arch/arm64/kvm/config.c b/arch/arm64/kvm/config.c index 467f57eb8e6b..1053676551af 100644 --- a/arch/arm64/kvm/config.c +++ b/arch/arm64/kvm/config.c @@ -1019,6 +1019,9 @@ static const struct reg_bits_to_feat_map hcr_feat_map[] = { static const DECLARE_FEAT_MAP(hcr_desc, HCR_EL2, hcr_feat_map, FEAT_AA64EL2); +static const DECLARE_FEAT_MAP(nvhcr_desc, NVHCR_EL2, + hcr_feat_map, FEAT_NV3); + static const struct reg_bits_to_feat_map sctlr2_feat_map[] = { NEEDS_FEAT(SCTLR2_EL1_NMEA | SCTLR2_EL1_EASE, @@ -1393,6 +1396,7 @@ void __init check_feature_map(void) check_reg_desc(&hdfgwtr2_desc); check_reg_desc(&hcrx_desc); check_reg_desc(&hcr_desc); + check_reg_desc(&nvhcr_desc); check_reg_desc(&sctlr2_desc); check_reg_desc(&tcr2_el2_desc); check_reg_desc(&sctlr_el1_desc); @@ -1592,6 +1596,17 @@ struct resx get_reg_fixed_bits(struct kvm *kvm, enum vcpu_sysreg reg) case HCR_EL2: resx = compute_reg_resx_bits(kvm, &hcr_desc, 0, 0); break; + case NVHCR_EL2: + /* + * Only apply sanitisation if we do have FEAT_NV3. + * Otherwise, the register aliases with HCR_EL2 in VNCR, + * and we're better off relying on data transfers between + * NVHCR_EL2 and HCR_EL2 to sanitise things. + */ + resx = (kvm_has_nv3(kvm) ? + compute_reg_resx_bits(kvm, &nvhcr_desc, 0, 0) : + (typeof(resx)){}); + break; case SCTLR2_EL1: case SCTLR2_EL2: resx = compute_reg_resx_bits(kvm, &sctlr2_desc, 0, 0); diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index 82be8bcb0703..34e63480886c 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -1828,6 +1828,10 @@ int kvm_init_nv_sysregs(struct kvm_vcpu *vcpu) resx = get_reg_fixed_bits(kvm, HCR_EL2); set_sysreg_masks(kvm, HCR_EL2, resx); + /* NVHCR_EL2 */ + resx = get_reg_fixed_bits(kvm, NVHCR_EL2); + set_sysreg_masks(kvm, NVHCR_EL2, resx); + /* HCRX_EL2 */ resx = get_reg_fixed_bits(kvm, HCRX_EL2); set_sysreg_masks(kvm, HCRX_EL2, resx);