Re: [RFC PATCH v2 2/8] KVM: arm64: Add KVM_PGTABLE_WALK_HW_DBM for HW DBM support

[Oliver Upton <oliver.upton@linux.dev>]

Hi Shameer,

On Fri, Aug 25, 2023 at 10:35:22AM +0100, Shameer Kolothum wrote:
> KVM_PGTABLE_WALK_HW_DBM - Indicates page table walk is for HW DBM
>  related updates.
> 
> No functional changes here. Only apply any HW DBM bit updates to last
> level only. These will be used by a future commit where we will add
> support for HW DBM.
> 
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
>  arch/arm64/include/asm/kvm_pgtable.h |  3 +++
>  arch/arm64/kvm/hyp/pgtable.c         | 10 ++++++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index d3e354bb8351..3f96bdd2086f 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -219,6 +219,8 @@ typedef bool (*kvm_pgtable_force_pte_cb_t)(u64 addr, u64 end,
>   * @KVM_PGTABLE_WALK_SKIP_CMO:		Visit and update table entries
>   *					without Cache maintenance
>   *					operations required.
> + * @KVM_PGTABLE_WALK_HW_DBM:		Indicates that the attribute update is
> + *					HW DBM related.
>   */
>  enum kvm_pgtable_walk_flags {
>  	KVM_PGTABLE_WALK_LEAF			= BIT(0),
> @@ -228,6 +230,7 @@ enum kvm_pgtable_walk_flags {
>  	KVM_PGTABLE_WALK_HANDLE_FAULT		= BIT(4),
>  	KVM_PGTABLE_WALK_SKIP_BBM_TLBI		= BIT(5),
>  	KVM_PGTABLE_WALK_SKIP_CMO		= BIT(6),
> +	KVM_PGTABLE_WALK_HW_DBM			= BIT(7),
>  };

Rather than making this DBM specific, call it KVM_PGTABLE_WALK_FORCE_PTE
and get rid of stage2_map_data::force_pte. Then it becomes immediately
obvious what this flag implies.

-- 
Thanks,
Oliver