From 7a765aa88e345782d3e4ed4c82e49f1ea82fd29c Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Sun, 17 Aug 2025 21:21:57 +0100 Subject: [PATCH] KVM: arm64: Make ID_AA64PFR1_EL1.RAS_frac writable Allow userspace to write to RAS_frac, under the condition that the host supports RASv1p1 with RAS_frac==1. Other configurations will result in RAS_frac being exposed as 0, and therefore implicitly not writable. To avoid the clutter, the ID_AA64PFR1_EL1 sanitisation is moved to its own function. Signed-off-by: Marc Zyngier Reviewed-by: Cornelia Huck Link: https://lore.kernel.org/r/20250817202158.395078-6-maz@kernel.org Signed-off-by: Oliver Upton --- arch/arm64/kvm/sys_regs.c | 41 ++++++++++++++++++++++++++------------- 1 file changed, 27 insertions(+), 14 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index bf160693963c8..5abe4db6c0084 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1584,6 +1584,7 @@ static u8 pmuver_to_perfmon(u8 pmuver) } static u64 sanitise_id_aa64pfr0_el1(const struct kvm_vcpu *vcpu, u64 val); +static u64 sanitise_id_aa64pfr1_el1(const struct kvm_vcpu *vcpu, u64 val); static u64 sanitise_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, u64 val); /* Read a sanitised cpufeature ID register by sys_reg_desc */ @@ -1606,19 +1607,7 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu, val = sanitise_id_aa64pfr0_el1(vcpu, val); break; case SYS_ID_AA64PFR1_EL1: - if (!kvm_has_mte(vcpu->kvm)) { - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE_frac); - } - - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_SME); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RNDR_trap); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_NMI); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_GCS); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_THE); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTEX); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_PFAR); - val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MPAM_frac); + val = sanitise_id_aa64pfr1_el1(vcpu, val); break; case SYS_ID_AA64PFR2_EL1: /* We only expose FPMR */ @@ -1834,6 +1823,31 @@ static u64 sanitise_id_aa64pfr0_el1(const struct kvm_vcpu *vcpu, u64 val) return val; } +static u64 sanitise_id_aa64pfr1_el1(const struct kvm_vcpu *vcpu, u64 val) +{ + u64 pfr0 = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); + + if (!kvm_has_mte(vcpu->kvm)) { + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE_frac); + } + + if (!(cpus_have_final_cap(ARM64_HAS_RASV1P1_EXTN) && + SYS_FIELD_GET(ID_AA64PFR0_EL1, RAS, pfr0) == ID_AA64PFR0_EL1_RAS_IMP)) + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RAS_frac); + + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_SME); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_RNDR_trap); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_NMI); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_GCS); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_THE); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTEX); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_PFAR); + val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MPAM_frac); + + return val; +} + static u64 sanitise_id_aa64dfr0_el1(const struct kvm_vcpu *vcpu, u64 val) { val = ID_REG_LIMIT_FIELD_ENUM(val, ID_AA64DFR0_EL1, DebugVer, V8P8); @@ -2952,7 +2966,6 @@ static const struct sys_reg_desc sys_reg_descs[] = { ID_AA64PFR1_EL1_SME | ID_AA64PFR1_EL1_RES0 | ID_AA64PFR1_EL1_MPAM_frac | - ID_AA64PFR1_EL1_RAS_frac | ID_AA64PFR1_EL1_MTE)), ID_WRITABLE(ID_AA64PFR2_EL1, ID_AA64PFR2_EL1_FPMR), ID_UNALLOCATED(4,3), -- 2.39.5