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

[Reiji Watanabe]

Hi Fuad,

On Mon, Jan 24, 2022 at 9:38 AM Fuad Tabba <tabba at google.com> wrote:
>
> Hi Reiji,
>
> The series might be missing an entry for ID_AA64MMFR0_EL1, Debug
> Communications Channel registers, ID_AA64MMFR0_FGT -> MDCR_EL2_TDCC.

I will add them in v5 series.
Thank you so much for all the review comments!

Thanks,
Reiji


>
> Cheers,
> /fuad
>
>
> On Thu, Jan 6, 2022 at 4:29 AM Reiji Watanabe <reijiw at 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 at 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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