On Fri, Mar 19, 2021 at 10:01:41AM +0000, Quentin Perret wrote:
> Introduce a new stage 2 configuration flag to specify that all mappings
> in a given page-table will be identity-mapped, as will be the case for
> the host. This allows to introduce sanity checks in the map path and to
> avoid programming errors.
>
> Suggested-by: Will Deacon <w...@kernel.org>
> Signed-off-by: Quentin Perret <qper...@google.com>
> ---
> arch/arm64/include/asm/kvm_pgtable.h | 2 ++
> arch/arm64/kvm/hyp/pgtable.c | 3 +++
> 2 files changed, 5 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h
> b/arch/arm64/include/asm/kvm_pgtable.h
> index 55452f4831d2..c3674c47d48c 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -60,9 +60,11 @@ 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.
> */
> enum kvm_pgtable_stage2_flags {
> KVM_PGTABLE_S2_NOFWB = BIT(0),
> + KVM_PGTABLE_S2_IDMAP = BIT(1),
> };
>
> /**
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index b22b4860630c..c37c1dc4feaf 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -760,6 +760,9 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64
> addr, u64 size,
> .arg = &map_data,
> };
>
> + if (WARN_ON((pgt->flags & KVM_PGTABLE_S2_IDMAP) && (addr != phys)))
> + return -EINVAL;
Acked-by: Will Deacon <w...@kernel.org>
Will
