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 <reijiw@xxxxxxxxxx>
---
arch/arm64/kvm/sys_regs.c | 98 +++++++++++++++++++++++++++++++++++++--
1 file changed, 94 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 2c092136cdff..536e313992d4 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -632,9 +632,6 @@ static struct id_reg_info id_aa64pfr0_el1_info = {
static struct id_reg_info id_aa64pfr1_el1_info = {
.sys_reg = SYS_ID_AA64PFR1_EL1,
- .ignore_mask = ARM64_FEATURE_MASK(ID_AA64PFR1_RASFRAC) |
- ARM64_FEATURE_MASK(ID_AA64PFR1_MPAMFRAC) |
- ARM64_FEATURE_MASK(ID_AA64PFR1_CSV2FRAC),
.init = init_id_aa64pfr1_el1_info,
.validate = validate_id_aa64pfr1_el1,
.get_reset_val = get_reset_id_aa64pfr1_el1,
@@ -3198,10 +3195,79 @@ 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 frac_id;
+ u32 id;
+ u64 frac_mask;
+ u64 mask;
+};
+
+static const struct feature_frac feature_frac_table[] = {
+ {
+ .frac_id = SYS_ID_AA64PFR1_EL1,
+ .frac_mask = ARM64_FEATURE_MASK(ID_AA64PFR1_RASFRAC),
+ .id = SYS_ID_AA64PFR0_EL1,
+ .mask = ARM64_FEATURE_MASK(ID_AA64PFR0_RAS),
+ },
+ {
+ .frac_id = SYS_ID_AA64PFR1_EL1,
+ .frac_mask = ARM64_FEATURE_MASK(ID_AA64PFR1_MPAMFRAC),
+ .id = SYS_ID_AA64PFR0_EL1,
+ .mask = ARM64_FEATURE_MASK(ID_AA64PFR0_MPAM),
+ },
+ {
+ .frac_id = SYS_ID_AA64PFR1_EL1,
+ .frac_mask = ARM64_FEATURE_MASK(ID_AA64PFR1_CSV2FRAC),
+ .id = SYS_ID_AA64PFR0_EL1,
+ .mask = ARM64_FEATURE_MASK(ID_AA64PFR0_CSV2),
+ },
+};
+
+/*
+ * Return non-zero if the feature/fractional fields pair are not
+ * supported. Return zero otherwise.
+ */
+static int vcpu_id_reg_feature_frac_check(const struct kvm_vcpu *vcpu,
+ const struct feature_frac *ftr_frac)
+{
+ const struct id_reg_info *id_reg;
+ u32 id;
+ u64 val, lim;
+ int err;
+
+ /* Check the feature field */
+ id = ftr_frac->id;
+ val = __vcpu_sys_reg(vcpu, IDREG_SYS_IDX(id)) & ftr_frac->mask;
+ id_reg = GET_ID_REG_INFO(id);
+ lim = id_reg ? id_reg->vcpu_limit_val : read_sanitised_ftr_reg(id);
+ lim &= ftr_frac->mask;
+ err = arm64_check_features(id, val, lim);
+ if (err)
+ /* The feature version is larger than the limit. */
+ return err;
+
+ if (val != lim)
+ /*
+ * The feature version is smaller than the limit.
+ * Any fractional version should be fine.
+ */
+ return 0;
+
+ /* Check the fractional field */
+ id = ftr_frac->frac_id;
+ val = __vcpu_sys_reg(vcpu, IDREG_SYS_IDX(id)) & ftr_frac->frac_mask;
+ id_reg = GET_ID_REG_INFO(id);
+ lim = id_reg ? id_reg->vcpu_limit_val : read_sanitised_ftr_reg(id);
+ lim &= ftr_frac->frac_mask;
+ return arm64_check_features(id, val, lim);
+}
+
int kvm_id_regs_consistency_check(const struct kvm_vcpu *vcpu)
{
- int i;
+ int i, err;
const struct kvm_vcpu *t_vcpu;
+ const struct feature_frac *frac;
/*
* Make sure vcpu->arch.has_run_once is visible for others so that
@@ -3222,6 +3288,17 @@ int kvm_id_regs_consistency_check(const struct kvm_vcpu *vcpu)
KVM_ARM_ID_REG_MAX_NUM))
return -EINVAL;
}
+
+ /*
+ * Check ID registers' fractional fields, which aren't checked
+ * when userspace sets.
+ */
+ 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;
}
@@ -3240,6 +3317,19 @@ static void id_reg_info_init_all(void)
else
id_reg_info_init(id_reg);
}
+
+ /*
+ * Update ignore_mask of ID registers based on fractional fields
+ * information. Any ID register that have fractional fields
+ * is expected to have its own id_reg_info.
+ */
+ for (i = 0; i < ARRAY_SIZE(feature_frac_table); i++) {
+ id_reg = GET_ID_REG_INFO(feature_frac_table[i].frac_id);
+ if (WARN_ON_ONCE(!id_reg))
+ continue;
+
+ id_reg->ignore_mask |= feature_frac_table[i].frac_mask;
+ }
}
void kvm_sys_reg_table_init(void)
--
2.33.0.882.g93a45727a2-goog
