[PATCH v2 12/17] arm64: Allow ID_AA64MMFR1_EL1.VH to be overridden from the command line

[Jing Zhang]

On Mon, Jan 4, 2021 at 8:20 AM Marc Zyngier <maz at kernel.org> wrote:
>
> As we want to be able to disable VHE at runtime, let's match
> "id_aa64mmfr1.vh=" from the command line as an override.
> This doesn't have much effect yet as out boot code doesn't look
Typo: out -> our
> at the cpufeature, but only at the HW registers.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/include/asm/cpufeature.h |  3 +++
>  arch/arm64/kernel/cpufeature.c      |  6 +++++-
>  arch/arm64/kernel/idreg-override.c  | 12 ++++++++++++
>  3 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index 465d2cb63bfc..ef9487dfadca 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -813,6 +813,9 @@ static inline unsigned int get_vmid_bits(u64 mmfr1)
>         return 8;
>  }
>
> +extern u64 id_aa64mmfr1_val;
> +extern u64 id_aa64mmfr1_mask;
> +
>  u32 get_kvm_ipa_limit(void);
>  void dump_cpu_features(void);
>
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 2dbfc0096b0d..623a74090c9e 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -555,6 +555,9 @@ static const struct arm64_ftr_bits ftr_raz[] = {
>
>  #define ARM64_FTR_REG(id, table) ARM64_FTR_REG_OVERRIDE(id, table, NULL, NULL)
>
> +u64 id_aa64mmfr1_val;
> +u64 id_aa64mmfr1_mask;
> +
>  static const struct __ftr_reg_entry {
>         u32                     sys_id;
>         struct arm64_ftr_reg    *reg;
> @@ -602,7 +605,8 @@ static const struct __ftr_reg_entry {
>
>         /* Op1 = 0, CRn = 0, CRm = 7 */
>         ARM64_FTR_REG(SYS_ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0),
> -       ARM64_FTR_REG(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1),
> +       ARM64_FTR_REG_OVERRIDE(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1,
> +                              &id_aa64mmfr1_val, &id_aa64mmfr1_mask),
>         ARM64_FTR_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2),
>
>         /* Op1 = 0, CRn = 1, CRm = 2 */
> diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
> index 392f93b67103..75d9845f489b 100644
> --- a/arch/arm64/kernel/idreg-override.c
> +++ b/arch/arm64/kernel/idreg-override.c
> @@ -10,6 +10,7 @@
>  #include <linux/libfdt.h>
>
>  #include <asm/cacheflush.h>
> +#include <asm/cpufeature.h>
>  #include <asm/setup.h>
>
>  struct reg_desc {
> @@ -22,7 +23,18 @@ struct reg_desc {
>         }                       fields[];
>  };
>
> +static const struct reg_desc mmfr1 __initdata = {
> +       .name           = "id_aa64mmfr1",
> +       .val            = &id_aa64mmfr1_val,
> +       .mask           = &id_aa64mmfr1_mask,
> +       .fields         = {
> +               { "vh", ID_AA64MMFR1_VHE_SHIFT },
> +               {}
> +       },
> +};
> +
>  static const struct reg_desc * const regs[] __initdata = {
> +       &mmfr1,
>  };
>
>  static int __init find_field(const char *cmdline, const struct reg_desc *reg,
> --
> 2.29.2
>
> _______________________________________________
> kvmarm mailing list
> kvmarm at lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm