On Sat, Oct 03, 2026 at 01:30:05PM +0100, Marc Zyngier wrote: > This *absolutely* needs to be data driven, and we're not going back to > over two years ago. We already have most of what is needed in > config.c, and it is only a matter of making sure that S1PxE is only > enabled for the guest if TCR2 and ATS1A are also present. If that > means additional sanitisation of the idregs when finalised, so be it. > > If userspace decides to expose crap in the ID registers, that's its > own problem, and we're not in the business of enforcing idiotic > configurations. The only thing that matters is that the state that KVM > deals with is consistent.
As I understand it: don't return an error for a configuration that doesn't make sense, enforce RES0 instead. So I'm guessing something like the below against the series (+ obviously adjusting tests to reflect that)? Cheers, Lorenzo ----8<---- >From b10625d0147f74504141da1f0c837b3b2bdd3d37 Mon Sep 17 00:00:00 2001 From: "Lorenzo Stoakes (ARM)" <[email protected]> Date: Wed, 14 Oct 2026 16:31:13 +0100 Subject: [PATCH] tmp --- arch/arm64/include/asm/kvm_host.h | 7 ++++++- arch/arm64/kvm/config.c | 35 ++++++++++++++++++++++--------- arch/arm64/kvm/sys_regs.c | 24 --------------------- 3 files changed, 31 insertions(+), 35 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 0eee9845324b..d5ba9867927f 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -1626,10 +1626,14 @@ void kvm_set_vm_id_reg(struct kvm *kvm, u32 reg, u64 val); (kvm_has_feat((k), ID_AA64MMFR3_EL1, TCRX, IMP)) #define kvm_has_s1pie(k) \ - (kvm_has_feat((k), ID_AA64MMFR3_EL1, S1PIE, IMP)) + (kvm_has_tcr2(k) && \ + kvm_has_feat((k), ID_AA64ISAR2_EL1, ATS1A, IMP) && \ + kvm_has_feat((k), ID_AA64MMFR3_EL1, S1PIE, IMP)) #define kvm_has_s1poe(k) \ (system_supports_poe() && \ + kvm_has_tcr2(k) && \ + kvm_has_feat((k), ID_AA64ISAR2_EL1, ATS1A, IMP) && \ kvm_has_feat((k), ID_AA64MMFR3_EL1, S1POE, IMP)) #define kvm_has_ras(k) \ @@ -1640,6 +1644,7 @@ void kvm_set_vm_id_reg(struct kvm *kvm, u32 reg, u64 val); #define kvm_has_gcs(k) \ (system_supports_gcs() && \ + kvm_has_s1pie(k) && \ kvm_has_feat((k), ID_AA64PFR1_EL1, GCS, IMP)) static inline bool kvm_arch_has_irq_bypass(void) diff --git a/arch/arm64/kvm/config.c b/arch/arm64/kvm/config.c index 1053676551af..58dab9cb2c04 100644 --- a/arch/arm64/kvm/config.c +++ b/arch/arm64/kvm/config.c @@ -232,6 +232,21 @@ static bool not_feat_aa64el3(struct kvm *kvm) return !kvm_has_feat(kvm, FEAT_AA64EL3); } +static bool feat_s1pie(struct kvm *kvm) +{ + return kvm_has_s1pie(kvm); +} + +static bool feat_s1poe(struct kvm *kvm) +{ + return kvm_has_s1poe(kvm); +} + +static bool feat_gcs(struct kvm *kvm) +{ + return kvm_has_gcs(kvm); +} + static bool feat_nv2(struct kvm *kvm) { return ((kvm_has_feat(kvm, ID_AA64MMFR4_EL1, NV_frac, NV2_ONLY) && @@ -393,17 +408,17 @@ static const struct reg_bits_to_feat_map hfgrtr_feat_map[] = { NEEDS_FEAT(HFGRTR_EL2_nS2POR_EL1, FEAT_S2POE), NEEDS_FEAT(HFGRTR_EL2_nPOR_EL1 | HFGRTR_EL2_nPOR_EL0, - FEAT_S1POE), + feat_s1poe), NEEDS_FEAT(HFGRTR_EL2_nPIR_EL1 | HFGRTR_EL2_nPIRE0_EL1, - FEAT_S1PIE), + feat_s1pie), NEEDS_FEAT(HFGRTR_EL2_nRCWMASK_EL1, FEAT_THE), NEEDS_FEAT(HFGRTR_EL2_nTPIDR2_EL0 | HFGRTR_EL2_nSMPRI_EL1, FEAT_SME), NEEDS_FEAT(HFGRTR_EL2_nGCS_EL1 | HFGRTR_EL2_nGCS_EL0, - FEAT_GCS), + feat_gcs), NEEDS_FEAT(HFGRTR_EL2_nACCDATA_EL1, FEAT_LS64_ACCDATA), NEEDS_FEAT(HFGRTR_EL2_ERXADDR_EL1 | HFGRTR_EL2_ERXMISCn_EL1 | @@ -474,17 +489,17 @@ static const struct reg_bits_to_feat_map hfgwtr_feat_map[] = { NEEDS_FEAT(HFGWTR_EL2_nS2POR_EL1, FEAT_S2POE), NEEDS_FEAT(HFGWTR_EL2_nPOR_EL1 | HFGWTR_EL2_nPOR_EL0, - FEAT_S1POE), + feat_s1poe), NEEDS_FEAT(HFGWTR_EL2_nPIR_EL1 | HFGWTR_EL2_nPIRE0_EL1, - FEAT_S1PIE), + feat_s1pie), NEEDS_FEAT(HFGWTR_EL2_nRCWMASK_EL1, FEAT_THE), NEEDS_FEAT(HFGWTR_EL2_nTPIDR2_EL0 | HFGWTR_EL2_nSMPRI_EL1, FEAT_SME), NEEDS_FEAT(HFGWTR_EL2_nGCS_EL1 | HFGWTR_EL2_nGCS_EL0, - FEAT_GCS), + feat_gcs), NEEDS_FEAT(HFGWTR_EL2_nACCDATA_EL1, FEAT_LS64_ACCDATA), NEEDS_FEAT(HFGWTR_EL2_ERXADDR_EL1 | HFGWTR_EL2_ERXMISCn_EL1 | @@ -674,7 +689,7 @@ static const struct reg_bits_to_feat_map hfgitr_feat_map[] = { NEEDS_FEAT(HFGITR_EL2_nGCSEPP | HFGITR_EL2_nGCSSTR_EL1 | HFGITR_EL2_nGCSPUSHM_EL1, - FEAT_GCS), + feat_gcs), NEEDS_FEAT(HFGITR_EL2_nBRBIALL | HFGITR_EL2_nBRBINJ, FEAT_BRBE), @@ -913,7 +928,7 @@ static const struct reg_bits_to_feat_map hcrx_feat_map[] = { NEEDS_FEAT(HCRX_EL2_SRMASKEn, FEAT_SRMASK), NEEDS_FEAT(HCRX_EL2_PACMEn, feat_pauth_lr), NEEDS_FEAT(HCRX_EL2_EnFPM, FEAT_FPMR), - NEEDS_FEAT(HCRX_EL2_GCSEn, FEAT_GCS), + NEEDS_FEAT(HCRX_EL2_GCSEn, feat_gcs), NEEDS_FEAT(HCRX_EL2_EnIDCP128, FEAT_SYSREG128), NEEDS_FEAT(HCRX_EL2_EnSDERR, feat_aderr), NEEDS_FEAT(HCRX_EL2_TMEA, FEAT_DoubleFault2), @@ -1062,8 +1077,8 @@ static const struct reg_bits_to_feat_map tcr2_el2_feat_map[] = { NEEDS_FEAT(TCR2_EL2_AIE, FEAT_AIE), NEEDS_FEAT(TCR2_EL2_POE | TCR2_EL2_E0POE, - FEAT_S1POE), - NEEDS_FEAT(TCR2_EL2_PIE, FEAT_S1PIE), + feat_s1poe), + NEEDS_FEAT(TCR2_EL2_PIE, feat_s1pie), FORCE_RES0(TCR2_EL2_RES0), FORCE_RES1(TCR2_EL2_RES1), }; diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 3e016ac40427..de48d2d1d761 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -5938,27 +5938,6 @@ void kvm_calculate_traps(struct kvm_vcpu *vcpu) mutex_unlock(&kvm->arch.config_lock); } -/* - * Some optimisations in fast paths would be broken by architecturally - * invalid feature combinations, reject those. - * - * This should share code with the host kernel cpufeature code, and - * make use of the MRS to generate dependencies. - */ -static bool kvm_validate_id_regs(struct kvm *kvm) -{ - if (kvm_has_s1pie(kvm) && !kvm_has_tcr2(kvm)) - return false; - - if (kvm_has_s1poe(kvm) && !kvm_has_tcr2(kvm)) - return false; - - if (kvm_has_gcs(kvm) && !kvm_has_s1pie(kvm)) - return false; - - return true; -} - /* * Perform last adjustments to the ID registers that are implied by the * configuration outside of the ID regs themselves, as well as any @@ -6027,9 +6006,6 @@ int kvm_finalize_sys_regs(struct kvm_vcpu *vcpu) kvm_vgic_finalize_idregs(kvm); } - if (!kvm_validate_id_regs(vcpu->kvm)) - return -EINVAL; - return 0; } -- 2.56.0
