[PATCH 4/6] KVM: arm64: Switch pKVM host S2 over to KVM_PGTABLE_S2_AS_S1

[Fuad Tabba]

On Mon, 19 Jan 2026 at 10:56, Marc Zyngier <maz at kernel.org> wrote:
>
> Since we have the basics to use the S1 memory attributes as the
> final ones with FWB, flip the host over to that when FWB is present.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index 49db32f3ddf71..38f66a56a7665 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -19,7 +19,7 @@
>  #include <nvhe/mem_protect.h>
>  #include <nvhe/mm.h>
>
> -#define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_NOFWB | KVM_PGTABLE_S2_IDMAP)
> +#define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_AS_S1 | KVM_PGTABLE_S2_IDMAP)
>
>  struct host_mmu host_mmu;
>
> @@ -324,6 +324,8 @@ int __pkvm_prot_finalize(void)
>         params->vttbr = kvm_get_vttbr(mmu);
>         params->vtcr = mmu->vtcr;
>         params->hcr_el2 |= HCR_VM;
> +       if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
> +               params->hcr_el2 |= HCR_FWB;

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

Cheers,
/fuad


>         /*
>          * The CMO below not only cleans the updated params to the
> --
> 2.47.3
>