[PATCH 08/20] KVM: arm64: Correctly handle SCTLR_EL1 RES1 bits for unsupported features

[Fuad Tabba]

Hi Marc,

On Mon, 26 Jan 2026 at 12:17, Marc Zyngier <maz at kernel.org> wrote:
>
> A bunch of SCTLR_EL1 bits must be set to RES1 when the controlling

nit: controlling

> feature is not present. Add the AS_RES1 qualifier where needed.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>

Otherwise, it matches the Arm Arm.

Reviewed-by: Fuad Tabba <tabba at google.com>

Cheers,
/fuad



> ---
>  arch/arm64/kvm/config.c | 26 ++++++++++++++------------
>  1 file changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm64/kvm/config.c b/arch/arm64/kvm/config.c
> index 6a4674fabf865..68ed5af2b4d53 100644
> --- a/arch/arm64/kvm/config.c
> +++ b/arch/arm64/kvm/config.c
> @@ -1085,27 +1085,28 @@ static const DECLARE_FEAT_MAP(tcr2_el2_desc, TCR2_EL2,
>                               tcr2_el2_feat_map, FEAT_TCR2);
>
>  static const struct reg_bits_to_feat_map sctlr_el1_feat_map[] = {
> -       NEEDS_FEAT(SCTLR_EL1_CP15BEN    |
> -                  SCTLR_EL1_ITD        |
> -                  SCTLR_EL1_SED,
> -                  FEAT_AA32EL0),
> +       NEEDS_FEAT(SCTLR_EL1_CP15BEN, FEAT_AA32EL0),
> +       NEEDS_FEAT_FLAG(SCTLR_EL1_ITD   |
> +                       SCTLR_EL1_SED,
> +                       AS_RES1, FEAT_AA32EL0),
>         NEEDS_FEAT(SCTLR_EL1_BT0        |
>                    SCTLR_EL1_BT1,
>                    FEAT_BTI),
>         NEEDS_FEAT(SCTLR_EL1_CMOW, FEAT_CMOW),
> -       NEEDS_FEAT(SCTLR_EL1_TSCXT, feat_csv2_2_csv2_1p2),
> -       NEEDS_FEAT(SCTLR_EL1_EIS        |
> -                  SCTLR_EL1_EOS,
> -                  FEAT_ExS),
> +       NEEDS_FEAT_FLAG(SCTLR_EL1_TSCXT,
> +                       AS_RES1, feat_csv2_2_csv2_1p2),
> +       NEEDS_FEAT_FLAG(SCTLR_EL1_EIS   |
> +                       SCTLR_EL1_EOS,
> +                       AS_RES1, FEAT_ExS),
>         NEEDS_FEAT(SCTLR_EL1_EnFPM, FEAT_FPMR),
>         NEEDS_FEAT(SCTLR_EL1_IESB, FEAT_IESB),
>         NEEDS_FEAT(SCTLR_EL1_EnALS, FEAT_LS64),
>         NEEDS_FEAT(SCTLR_EL1_EnAS0, FEAT_LS64_ACCDATA),
>         NEEDS_FEAT(SCTLR_EL1_EnASR, FEAT_LS64_V),
>         NEEDS_FEAT(SCTLR_EL1_nAA, FEAT_LSE2),
> -       NEEDS_FEAT(SCTLR_EL1_LSMAOE     |
> -                  SCTLR_EL1_nTLSMD,
> -                  FEAT_LSMAOC),
> +       NEEDS_FEAT_FLAG(SCTLR_EL1_LSMAOE        |
> +                       SCTLR_EL1_nTLSMD,
> +                       AS_RES1, FEAT_LSMAOC),
>         NEEDS_FEAT(SCTLR_EL1_EE, FEAT_MixedEnd),
>         NEEDS_FEAT(SCTLR_EL1_E0E, feat_mixedendel0),
>         NEEDS_FEAT(SCTLR_EL1_MSCEn, FEAT_MOPS),
> @@ -1121,7 +1122,8 @@ static const struct reg_bits_to_feat_map sctlr_el1_feat_map[] = {
>         NEEDS_FEAT(SCTLR_EL1_NMI        |
>                    SCTLR_EL1_SPINTMASK,
>                    FEAT_NMI),
> -       NEEDS_FEAT(SCTLR_EL1_SPAN, FEAT_PAN),
> +       NEEDS_FEAT_FLAG(SCTLR_EL1_SPAN,
> +                       AS_RES1, FEAT_PAN),
>         NEEDS_FEAT(SCTLR_EL1_EPAN, FEAT_PAN3),
>         NEEDS_FEAT(SCTLR_EL1_EnDA       |
>                    SCTLR_EL1_EnDB       |
> --
> 2.47.3
>