Re: [RFC PATCH v4 23/26] KVM: arm64: Trap disabled features of ID_AA64MMFR1_EL1

[Fuad Tabba <tabba@google.com>]

Hi Reiji,

The series might be missing an entry for ID_AA64MMFR0_EL1, Debug
Communications Channel registers, ID_AA64MMFR0_FGT -> MDCR_EL2_TDCC.

Cheers,
/fuad


On Thu, Jan 6, 2022 at 4:29 AM Reiji Watanabe <reijiw@google.com> wrote:
>
> Add feature_config_ctrl for LORegions, which is indicated in
> ID_AA64MMFR1_EL1, to program configuration register to trap
> guest's using the feature when it is not exposed to the guest.
>
> Change trap_loregion() to use vcpu_feature_is_available()
> to simplify checking of the feature's availability.
>
> Signed-off-by: Reiji Watanabe <reijiw@google.com>
> ---
>  arch/arm64/kvm/sys_regs.c | 26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 229671ec3abd..f8a5ee927ecf 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -365,6 +365,11 @@ static void feature_tracefilt_trap_activate(struct kvm_vcpu *vcpu)
>         feature_trap_activate(vcpu, VCPU_MDCR_EL2, MDCR_EL2_TTRF, 0);
>  }
>
> +static void feature_lor_trap_activate(struct kvm_vcpu *vcpu)
> +{
> +       feature_trap_activate(vcpu, VCPU_HCR_EL2, HCR_TLOR, 0);
> +}
> +
>  /* For ID_AA64PFR0_EL1 */
>  static struct feature_config_ctrl ftr_ctrl_ras = {
>         .ftr_reg = SYS_ID_AA64PFR0_EL1,
> @@ -416,6 +421,15 @@ static struct feature_config_ctrl ftr_ctrl_tracefilt = {
>         .trap_activate = feature_tracefilt_trap_activate,
>  };
>
> +/* For ID_AA64MMFR1_EL1 */
> +static struct feature_config_ctrl ftr_ctrl_lor = {
> +       .ftr_reg = SYS_ID_AA64MMFR1_EL1,
> +       .ftr_shift = ID_AA64MMFR1_LOR_SHIFT,
> +       .ftr_min = 1,
> +       .ftr_signed = FTR_UNSIGNED,
> +       .trap_activate = feature_lor_trap_activate,
> +};
> +
>  struct id_reg_info {
>         u32     sys_reg;        /* Register ID */
>         u64     sys_val;        /* Sanitized system value */
> @@ -947,6 +961,14 @@ static struct id_reg_info id_aa64dfr0_el1_info = {
>         },
>  };
>
> +static struct id_reg_info id_aa64mmfr1_el1_info = {
> +       .sys_reg = SYS_ID_AA64MMFR1_EL1,
> +       .trap_features = &(const struct feature_config_ctrl *[]) {
> +               &ftr_ctrl_lor,
> +               NULL,
> +       },
> +};
> +
>  static struct id_reg_info id_dfr0_el1_info = {
>         .sys_reg = SYS_ID_DFR0_EL1,
>         .init = init_id_dfr0_el1_info,
> @@ -976,6 +998,7 @@ static struct id_reg_info *id_reg_info_table[KVM_ARM_ID_REG_MAX_NUM] = {
>         [IDREG_IDX(SYS_ID_AA64ISAR0_EL1)] = &id_aa64isar0_el1_info,
>         [IDREG_IDX(SYS_ID_AA64ISAR1_EL1)] = &id_aa64isar1_el1_info,
>         [IDREG_IDX(SYS_ID_AA64MMFR0_EL1)] = &id_aa64mmfr0_el1_info,
> +       [IDREG_IDX(SYS_ID_AA64MMFR1_EL1)] = &id_aa64mmfr1_el1_info,
>  };
>
>  static int validate_id_reg(struct kvm_vcpu *vcpu, u32 id, u64 val)
> @@ -1050,10 +1073,9 @@ static bool trap_loregion(struct kvm_vcpu *vcpu,
>                           struct sys_reg_params *p,
>                           const struct sys_reg_desc *r)
>  {
> -       u64 val = __read_id_reg(vcpu, SYS_ID_AA64MMFR1_EL1);
>         u32 sr = reg_to_encoding(r);
>
> -       if (!(val & (0xfUL << ID_AA64MMFR1_LOR_SHIFT))) {
> +       if (!vcpu_feature_is_available(vcpu, &ftr_ctrl_lor)) {
>                 kvm_inject_undefined(vcpu);
>                 return false;
>         }
> --
> 2.34.1.448.ga2b2bfdf31-goog
>
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