This patch adds id_reg_info for ID_DFR0_EL1 to make it writable by userspace. Return an error if userspace tries to set PerfMon field of the register to a value that conflicts with the PMU configuration. Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx> --- arch/arm64/kvm/sys_regs.c | 58 +++++++++++++++++++++++++++++++-------- 1 file changed, 47 insertions(+), 11 deletions(-) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 54bc3641d582..8abd3f6fd667 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -654,6 +654,27 @@ static int validate_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, return 0; } +static int validate_id_dfr0_el1(struct kvm_vcpu *vcpu, + const struct id_reg_info *id_reg, u64 val) +{ + bool vcpu_pmu, dfr0_pmu; + unsigned int perfmon; + + perfmon = cpuid_feature_extract_unsigned_field(val, ID_DFR0_PERFMON_SHIFT); + if (perfmon == 1 || perfmon == 2) + /* PMUv1 or PMUv2 is not allowed on ARMv8. */ + return -EINVAL; + + vcpu_pmu = kvm_vcpu_has_pmu(vcpu); + dfr0_pmu = id_reg_has_pmu(val, ID_DFR0_PERFMON_SHIFT, ID_DFR0_PERFMON_8_0); + + /* Check if there is a conflict with a request via KVM_ARM_VCPU_INIT */ + if (vcpu_pmu ^ dfr0_pmu) + return -EPERM; + + return 0; +} + static void init_id_aa64pfr0_el1_info(struct id_reg_info *id_reg) { u64 limit = id_reg->vcpu_limit_val; @@ -707,6 +728,15 @@ static void init_id_aa64dfr0_el1_info(struct id_reg_info *id_reg) id_reg->vcpu_limit_val = limit; } +static void init_id_dfr0_el1_info(struct id_reg_info *id_reg) +{ + /* Limit guests to PMUv3 for ARMv8.4 */ + id_reg->vcpu_limit_val = + cpuid_feature_cap_perfmon_field(id_reg->vcpu_limit_val, + ID_DFR0_PERFMON_SHIFT, + ID_DFR0_PERFMON_8_4); +} + static u64 get_reset_id_aa64pfr0_el1(struct kvm_vcpu *vcpu, const struct id_reg_info *idr) { @@ -738,6 +768,14 @@ static u64 get_reset_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, (idr->vcpu_limit_val & ~(ARM64_FEATURE_MASK(ID_AA64DFR0_PMUVER))); } +static u64 get_reset_id_dfr0_el1(struct kvm_vcpu *vcpu, + const struct id_reg_info *idr) +{ + return kvm_vcpu_has_pmu(vcpu) ? + idr->vcpu_limit_val : + (idr->vcpu_limit_val & ~(ARM64_FEATURE_MASK(ID_DFR0_PERFMON))); +} + static struct id_reg_info id_aa64pfr0_el1_info = { .sys_reg = SYS_ID_AA64PFR0_EL1, .ftr_check_types = S_FCT(ID_AA64PFR0_ASIMD_SHIFT, FCT_LOWER_SAFE) | @@ -790,6 +828,13 @@ static struct id_reg_info id_aa64dfr0_el1_info = { .get_reset_val = get_reset_id_aa64dfr0_el1, }; +static struct id_reg_info id_dfr0_el1_info = { + .sys_reg = SYS_ID_DFR0_EL1, + .init = init_id_dfr0_el1_info, + .validate = validate_id_dfr0_el1, + .get_reset_val = get_reset_id_dfr0_el1, +}; + /* * An ID register that needs special handling to control the value for the * guest must have its own id_reg_info in id_reg_info_table. @@ -799,6 +844,7 @@ static struct id_reg_info id_aa64dfr0_el1_info = { */ #define GET_ID_REG_INFO(id) (id_reg_info_table[IDREG_IDX(id)]) static struct id_reg_info *id_reg_info_table[KVM_ARM_ID_REG_MAX_NUM] = { + [IDREG_IDX(SYS_ID_DFR0_EL1)] = &id_dfr0_el1_info, [IDREG_IDX(SYS_ID_AA64PFR0_EL1)] = &id_aa64pfr0_el1_info, [IDREG_IDX(SYS_ID_AA64PFR1_EL1)] = &id_aa64pfr1_el1_info, [IDREG_IDX(SYS_ID_AA64DFR0_EL1)] = &id_aa64dfr0_el1_info, @@ -1636,18 +1682,8 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc const *r, bool raz) { u32 id = reg_to_encoding(r); - u64 val = raz ? 0 : __vcpu_sys_reg(vcpu, IDREG_SYS_IDX(id)); - - switch (id) { - case SYS_ID_DFR0_EL1: - /* Limit guests to PMUv3 for ARMv8.4 */ - val = cpuid_feature_cap_perfmon_field(val, - ID_DFR0_PERFMON_SHIFT, - kvm_vcpu_has_pmu(vcpu) ? ID_DFR0_PERFMON_8_4 : 0); - break; - } - return val; + return raz ? 0 : __vcpu_sys_reg(vcpu, IDREG_SYS_IDX(id)); } static unsigned int id_visibility(const struct kvm_vcpu *vcpu, -- 2.33.1.1089.g2158813163f-goog _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm