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 <redacted>
---
 arch/arm64/include/asm/kvm_host.h |   1 +
 arch/arm64/kvm/arm.c              |   3 +
 arch/arm64/kvm/sys_regs.c         | 116 +++++++++++++++++++++++++++++-
 3 files changed, 117 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 4509f9e7472d..7b3f86bd6a6b 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h

@@ -750,6 +750,7 @@ long kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm,

 void set_default_id_regs(struct kvm *kvm);
 int kvm_set_id_reg_feature(struct kvm *kvm, u32 id, u8 field_shift, u8 fval);
+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);

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 5f497a0af254..16fc2ce32069 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c

@@ -596,6 +596,9 @@ 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 ddbeefc3881c..6adb7b04620c 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c

@@ -756,9 +756,6 @@ 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,
        .vcpu_mask = vcpu_mask_id_aa64pfr1_el1,

@@ -3434,10 +3431,109 @@ 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;
+};

+{
+       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 ftr_mask = ARM64_FEATURE_FIELD_MASK;

        for (i = 0; i < ARRAY_SIZE(id_reg_info_table); i++) {
                id_reg = (struct id_reg_info *)id_reg_info_table[i];

@@ -3446,6 +3542,20 @@ static void id_reg_info_init_all(void)

                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++) {
+               frac = &feature_frac_table[i];
+               id_reg = GET_ID_REG_INFO(frac->frac_id);
+               if (WARN_ON_ONCE(!id_reg))
+                       continue;
+
+               id_reg->ignore_mask |= ftr_mask << frac->frac_shift;
+       }
 }