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Tue, 16 Nov 2021 22:53:33 -0800 (PST) Date: Tue, 16 Nov 2021 22:43:46 -0800 In-Reply-To: <20211117064359.2362060-1-reijiw@google.com> Message-Id: <20211117064359.2362060-17-reijiw@google.com> Mime-Version: 1.0 References: <20211117064359.2362060-1-reijiw@google.com> X-Mailer: git-send-email 2.34.0.rc1.387.gb447b232ab-goog Subject: [RFC PATCH v3 16/29] KVM: arm64: Add consistency checking for frac fields of ID registers From: Reiji Watanabe To: Marc Zyngier , kvmarm@lists.cs.columbia.edu Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, James Morse , Alexandru Elisei , Suzuki K Poulose , Paolo Bonzini , Will Deacon , Andrew Jones , Peng Liang , Peter Shier , Ricardo Koller , Oliver Upton , Jing Zhang , Raghavendra Rao Anata , Reiji Watanabe X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211116_225335_457358_BA3CA550 X-CRM114-Status: GOOD ( 22.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Feature fractional field of an ID register cannot be simply validated at KVM_SET_ONE_REG because its validity depends on its (main) feature field value, which could be in a different ID register (and might be set later). Validate fractional fields at the first KVM_RUN instead. Signed-off-by: Reiji Watanabe --- arch/arm64/include/asm/kvm_host.h | 2 + arch/arm64/kvm/arm.c | 3 + arch/arm64/kvm/sys_regs.c | 125 +++++++++++++++++++++++++++++- 3 files changed, 127 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 72db73c79403..9dc9970a2d46 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -746,6 +746,8 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu, long kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, struct kvm_arm_copy_mte_tags *copy_tags); +int kvm_id_regs_consistency_check(const struct kvm_vcpu *vcpu); + /* Guest/host FPSIMD coordination helpers */ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu); void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu); diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 2f03cbfefe67..19c4a78f931d 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -588,6 +588,9 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu) if (!kvm_arm_vcpu_is_finalized(vcpu)) return -EPERM; + if (!kvm_vm_is_protected(kvm) && kvm_id_regs_consistency_check(vcpu)) + return -EPERM; + vcpu->arch.has_run_once = true; kvm_arm_vcpu_init_debug(vcpu); diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 35e458cc1e1d..b848ecea0c59 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -841,9 +841,6 @@ static struct id_reg_info id_aa64pfr0_el1_info = { static struct id_reg_info id_aa64pfr1_el1_info = { .sys_reg = SYS_ID_AA64PFR1_EL1, - .ftr_check_types = U_FCT(ID_AA64PFR1_RASFRAC_SHIFT, FCT_IGNORE) | - U_FCT(ID_AA64PFR1_MPAMFRAC_SHIFT, FCT_IGNORE) | - U_FCT(ID_AA64PFR1_CSV2FRAC_SHIFT, FCT_IGNORE), .init = init_id_aa64pfr1_el1_info, .validate = validate_id_aa64pfr1_el1, .get_reset_val = get_reset_id_aa64pfr1_el1, @@ -3460,10 +3457,106 @@ int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) return write_demux_regids(uindices); } +/* ID register's fractional field information with its feature field. */ +struct feature_frac { + u32 id; + u32 shift; + u32 frac_id; + u32 frac_shift; + u8 frac_ftr_check; +}; + +static struct feature_frac feature_frac_table[] = { + { + .frac_id = SYS_ID_AA64PFR1_EL1, + .frac_shift = ID_AA64PFR1_RASFRAC_SHIFT, + .id = SYS_ID_AA64PFR0_EL1, + .shift = ID_AA64PFR0_RAS_SHIFT, + }, + { + .frac_id = SYS_ID_AA64PFR1_EL1, + .frac_shift = ID_AA64PFR1_MPAMFRAC_SHIFT, + .id = SYS_ID_AA64PFR0_EL1, + .shift = ID_AA64PFR0_MPAM_SHIFT, + }, + { + .frac_id = SYS_ID_AA64PFR1_EL1, + .frac_shift = ID_AA64PFR1_CSV2FRAC_SHIFT, + .id = SYS_ID_AA64PFR0_EL1, + .shift = ID_AA64PFR0_CSV2_SHIFT, + }, +}; + +/* + * Return non-zero if the feature/fractional fields pair are not + * supported. Return zero otherwise. + * This function only checks fractional feature field and assumes + * the feature field is valid. + */ +static int vcpu_id_reg_feature_frac_check(const struct kvm_vcpu *vcpu, + const struct feature_frac *ftr_frac) +{ + u32 id; + int fval, flim, ret; + u64 val, lim, mask; + const struct id_reg_info *id_reg; + bool sign = FCT_SIGN(ftr_frac->frac_ftr_check); + enum feature_check_type type = FCT_TYPE(ftr_frac->frac_ftr_check); + + /* Check if the feature field value is same as the limit */ + id = ftr_frac->id; + id_reg = GET_ID_REG_INFO(id); + + val = __read_id_reg(vcpu, id); + lim = id_reg ? id_reg->vcpu_limit_val : read_sanitised_ftr_reg(id); + + mask = (u64)ARM64_FEATURE_FIELD_MASK << ftr_frac->shift; + if ((val & mask) != (lim & mask)) + /* + * The feature level is smaller than the limit. + * Any fractional version should be fine. + */ + return 0; + + /* Check the fractional feature field */ + id = ftr_frac->frac_id; + id_reg = GET_ID_REG_INFO(id); + + val = __read_id_reg(vcpu, id); + fval = cpuid_feature_extract_field(val, ftr_frac->frac_shift, sign); + + lim = id_reg ? id_reg->vcpu_limit_val : read_sanitised_ftr_reg(id); + flim = cpuid_feature_extract_field(lim, ftr_frac->frac_shift, sign); + + ret = arm64_check_feature_one(type, fval, flim); + return ret ? -E2BIG : 0; +} + +int kvm_id_regs_consistency_check(const struct kvm_vcpu *vcpu) +{ + int i, err; + const struct feature_frac *frac; + + /* + * Check ID registers' fractional fields, which aren't checked + * at KVM_SET_ONE_REG. + */ + for (i = 0; i < ARRAY_SIZE(feature_frac_table); i++) { + frac = &feature_frac_table[i]; + err = vcpu_id_reg_feature_frac_check(vcpu, frac); + if (err) + return err; + } + return 0; +} + static void id_reg_info_init_all(void) { int i; struct id_reg_info *id_reg; + struct feature_frac *frac; + u64 mask = ARM64_FEATURE_FIELD_MASK; + u64 org; for (i = 0; i < ARRAY_SIZE(id_reg_info_table); i++) { id_reg = (struct id_reg_info *)id_reg_info_table[i]; @@ -3472,6 +3565,32 @@ static void id_reg_info_init_all(void) id_reg_info_init(id_reg); } + + for (i = 0; i < ARRAY_SIZE(feature_frac_table); i++) { + frac = &feature_frac_table[i]; + id_reg = GET_ID_REG_INFO(frac->frac_id); + + /* + * An ID register that has fractional fields is expected + * to have its own id_reg_info. + */ + if (WARN_ON_ONCE(!id_reg)) + continue; + + /* + * Update the id_reg's ftr_check_types for the fractional + * field with FCT_IGNORE so that the field won't be validated + * when the ID register is set by userspace, which could + * temporarily cause an inconsistency if its (main) feature + * field is not set yet. Save the original ftr_check_types + * for the fractional field to validate the field later. + */ + org = (id_reg->ftr_check_types >> frac->frac_shift) & mask; + id_reg->ftr_check_types &= ~(mask << frac->frac_shift); + id_reg->ftr_check_types |= + MAKE_FCT(frac->frac_shift, FCT_IGNORE, FCT_SIGN(org)); + frac->frac_ftr_check = org; + } } void kvm_sys_reg_table_init(void) -- 2.34.0.rc1.387.gb447b232ab-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel