This patch adds id_reg_desc for ID_AA64MMFR0_EL1 to make it writable by userspace. Since ID_AA64MMFR0_EL1 stage 2 granule size fields don't follow the standard ID scheme, we need a special handling to validate those fields. Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx> --- arch/arm64/kvm/sys_regs.c | 129 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 33b4918109b7..ad23361d3a3b 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -460,6 +460,118 @@ static int validate_id_aa64isar1_el1(struct kvm_vcpu *vcpu, return 0; } +/* + * Check if the requested stage2 translation granule size indicated in + * @mmfr0 is also indicated in @mmfr0_lim. + * If TGranX_2 field is zero, the value must be validated based on TGranX + * field because that indicates the feature support is identified in + * TGranX field. + * This function relies on the fact TGranX fields are validated before + * through arm64_check_features_kvm. + */ +static int aa64mmfr0_tgran2_check(int field, u64 mmfr0, u64 mmfr0_lim) +{ + s64 tgran2, lim_tgran2, rtgran1; + int f1; + bool is_signed; + + tgran2 = cpuid_feature_extract_unsigned_field(mmfr0, field); + lim_tgran2 = cpuid_feature_extract_unsigned_field(mmfr0_lim, field); + if (tgran2 && lim_tgran2) + /* + * We don't need to check TGranX field. We can simply + * compare tgran2 and lim_tgran2. + */ + return (tgran2 > lim_tgran2) ? -E2BIG : 0; + + if (tgran2 == lim_tgran2) + /* + * Both of them are zero. Since TGranX in @mmfr0 is already + * validated by arm64_check_features_kvm, tgran2 must be fine. + */ + return 0; + + /* + * Either tgran2 or lim_tgran2 is zero. + * Need stage1 granule size to validate tgran2. + */ + + /* + * Get TGranX's bit position by subtracting 12 from TGranX_2's bit + * position. + */ + f1 = field - 12; + + /* TGran4/TGran64 is signed and TGran16 is unsigned field. */ + is_signed = (f1 == ID_AA64MMFR0_TGRAN16_SHIFT) ? false : true; + + /* + * If tgran2 == 0 (&& lim_tgran2 != 0), the requested stage2 granule + * size is indicated in the stage1 granule size field of @mmfr0. + * So, validate the stage1 granule size against the stage2 limit + * granule size. + * If lim_tgran2 == 0 (&& tgran2 != 0), the stage2 limit granule size + * is indicated in the stage1 granule size field of @mmfr0_lim. + * So, validate the requested stage2 granule size against the stage1 + * limit granule size. + */ + + /* Get the relevant stage1 granule size to validate tgran2 */ + if (tgran2 == 0) + /* The requested stage1 granule size */ + rtgran1 = cpuid_feature_extract_field(mmfr0, f1, is_signed); + else /* lim_tgran2 == 0 */ + /* The stage1 limit granule size */ + rtgran1 = cpuid_feature_extract_field(mmfr0_lim, f1, is_signed); + + /* + * Adjust the value of rtgran1 to compare with stage2 granule size, + * which indicates: 1: Not supported, 2: Supported, etc. + */ + if (is_signed) + /* For signed, -1: Not supported, 0: Supported, etc. */ + rtgran1 += 0x2; + else + /* For unsigned, 0: Not supported, 1: Supported, etc. */ + rtgran1 += 0x1; + + if ((tgran2 == 0) && (rtgran1 > lim_tgran2)) + /* + * The requested stage1 granule size (== the requested stage2 + * granule size) is larger than the stage2 limit granule size. + */ + return -E2BIG; + else if ((lim_tgran2 == 0) && (tgran2 > rtgran1)) + /* + * The requested stage2 granule size is larger than the stage1 + * limit granulze size (== the stage2 limit granule size). + */ + return -E2BIG; + + return 0; +} + +static int validate_id_aa64mmfr0_el1(struct kvm_vcpu *vcpu, + const struct id_reg_desc *id_reg, u64 val) +{ + u64 limit = id_reg->vcpu_limit_val; + int ret; + + ret = aa64mmfr0_tgran2_check(ID_AA64MMFR0_TGRAN4_2_SHIFT, val, limit); + if (ret) + return ret; + + ret = aa64mmfr0_tgran2_check(ID_AA64MMFR0_TGRAN64_2_SHIFT, val, limit); + if (ret) + return ret; + + ret = aa64mmfr0_tgran2_check(ID_AA64MMFR0_TGRAN16_2_SHIFT, val, limit); + if (ret) + return ret; + + return 0; +} + static void init_id_aa64pfr0_el1_desc(struct id_reg_desc *id_reg) { u64 limit = id_reg->vcpu_limit_val; @@ -3255,6 +3367,20 @@ static struct id_reg_desc id_aa64isar1_el1_desc = { .vcpu_mask = vcpu_mask_id_aa64isar1_el1, }; +static struct id_reg_desc id_aa64mmfr0_el1_desc = { + .reg_desc = ID_SANITISED(ID_AA64MMFR0_EL1), + /* + * When TGranX_2 value is 0, validity of the value depend on TGranX + * value, and TGranX_2 value must be validated against TGranX value, + * which is done by validate_id_aa64mmfr0_el1. + * So, skip the regular validity checking for TGranX_2 fields. + */ + .ignore_mask = ARM64_FEATURE_MASK(ID_AA64MMFR0_TGRAN4_2) | + ARM64_FEATURE_MASK(ID_AA64MMFR0_TGRAN64_2) | + ARM64_FEATURE_MASK(ID_AA64MMFR0_TGRAN16_2), + .validate = validate_id_aa64mmfr0_el1, +}; + #define ID_DESC(id_reg_name, id_reg_desc) \ [IDREG_IDX(SYS_##id_reg_name)] = (id_reg_desc) @@ -3267,6 +3393,9 @@ static struct id_reg_desc *id_reg_desc_table[KVM_ARM_ID_REG_MAX_NUM] = { /* CRm=6 */ ID_DESC(ID_AA64ISAR0_EL1, &id_aa64isar0_el1_desc), ID_DESC(ID_AA64ISAR1_EL1, &id_aa64isar1_el1_desc), + + /* CRm=7 */ + ID_DESC(ID_AA64MMFR0_EL1, &id_aa64mmfr0_el1_desc), }; static inline struct id_reg_desc *get_id_reg_desc(u32 id) -- 2.35.1.723.g4982287a31-goog