[PATCH 5/6] KVM: arm64: Kill KVM_PGTABLE_S2_NOFWB

[Fuad Tabba]

On Mon, 19 Jan 2026 at 10:56, Marc Zyngier <maz at kernel.org> wrote:
>
> Nobody is using this flag anymore, so remove it. This allows
> some cleanup for stage2_has_fwb(), whic doesn't need to take the

nit: s/whic/which

> pgt as a parameter anymore.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>

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

Cheers,
/fuad




> ---
>  arch/arm64/include/asm/kvm_pgtable.h |  7 ++-----
>  arch/arm64/kvm/hyp/pgtable.c         | 17 +++++++----------
>  2 files changed, 9 insertions(+), 15 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index 9ce51a637da0a..2198b62428832 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -229,15 +229,12 @@ struct kvm_pgtable_mm_ops {
>
>  /**
>   * enum kvm_pgtable_stage2_flags - Stage-2 page-table flags.
> - * @KVM_PGTABLE_S2_NOFWB:      Don't enforce Normal-WB even if the CPUs have
> - *                             ARM64_HAS_STAGE2_FWB.
>   * @KVM_PGTABLE_S2_IDMAP:      Only use identity mappings.
>   * @KVM_PGTABLE_S2_AS_S1:      Final memory attributes are that of Stage-1.
>   */
>  enum kvm_pgtable_stage2_flags {
> -       KVM_PGTABLE_S2_NOFWB                    = BIT(0),
> -       KVM_PGTABLE_S2_IDMAP                    = BIT(1),
> -       KVM_PGTABLE_S2_AS_S1                    = BIT(2),
> +       KVM_PGTABLE_S2_IDMAP                    = BIT(0),
> +       KVM_PGTABLE_S2_AS_S1                    = BIT(1),
>  };
>
>  /**
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 07561a227f75e..3c2f7967fdc03 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -631,12 +631,9 @@ u64 kvm_get_vtcr(u64 mmfr0, u64 mmfr1, u32 phys_shift)
>         return vtcr;
>  }
>
> -static bool stage2_has_fwb(struct kvm_pgtable *pgt)
> +static bool stage2_has_fwb(void)
>  {
> -       if (!cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
> -               return false;
> -
> -       return !(pgt->flags & KVM_PGTABLE_S2_NOFWB);
> +       return cpus_have_final_cap(ARM64_HAS_STAGE2_FWB);
>  }
>
>  void kvm_tlb_flush_vmid_range(struct kvm_s2_mmu *mmu,
> @@ -664,10 +661,10 @@ void kvm_tlb_flush_vmid_range(struct kvm_s2_mmu *mmu,
>                 kvm_pte_t __attr;                                       \
>                 if((pgt)->flags & KVM_PGTABLE_S2_AS_S1)                 \
>                         __attr = PAGE_S2_MEMATTR(AS_S1,                 \
> -                                                stage2_has_fwb(pgt));  \
> +                                                stage2_has_fwb());     \
>                 else                                                    \
>                         __attr = PAGE_S2_MEMATTR(attr,                  \
> -                                                stage2_has_fwb(pgt));  \
> +                                                stage2_has_fwb());     \
>                                                                         \
>                 __attr;                                                 \
>         })
> @@ -879,7 +876,7 @@ static bool stage2_unmap_defer_tlb_flush(struct kvm_pgtable *pgt)
>          * system supporting FWB as the optimization is entirely
>          * pointless when the unmap walker needs to perform CMOs.
>          */
> -       return system_supports_tlb_range() && stage2_has_fwb(pgt);
> +       return system_supports_tlb_range() && stage2_has_fwb();
>  }
>
>  static void stage2_unmap_put_pte(const struct kvm_pgtable_visit_ctx *ctx,
> @@ -1167,7 +1164,7 @@ static int stage2_unmap_walker(const struct kvm_pgtable_visit_ctx *ctx,
>                 if (mm_ops->page_count(childp) != 1)
>                         return 0;
>         } else if (stage2_pte_cacheable(pgt, ctx->old)) {
> -               need_flush = !stage2_has_fwb(pgt);
> +               need_flush = !stage2_has_fwb();
>         }
>
>         /*
> @@ -1397,7 +1394,7 @@ int kvm_pgtable_stage2_flush(struct kvm_pgtable *pgt, u64 addr, u64 size)
>                 .arg    = pgt,
>         };
>
> -       if (stage2_has_fwb(pgt))
> +       if (stage2_has_fwb())
>                 return 0;
>
>         return kvm_pgtable_walk(pgt, addr, size, &walker);
> --
> 2.47.3
>