Re: [PATCH v3 12/21] KVM: arm64: Add support for stage-2 write-protect in generic page-table

Gavin Shan
2020-09-03T04:48:56Z

Hi Will,

On 8/25/20 7:39 PM, Will Deacon wrote:
> From: Quentin Perret <qperret@google.com>
>
> Add a stage-2 wrprotect() operation to the generic page-table code.
>
> Cc: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Quentin Perret <qperret@google.com>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---

Reviewed-by: Gavin Shan <gshan@redhat.com>

> arch/arm64/include/asm/kvm_pgtable.h | 15 +++++++++++++++
> arch/arm64/kvm/hyp/pgtable.c | 6 ++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index ae56534f87a0..0c96b78d791d 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -173,6 +173,21 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> */
> int kvm_pgtable_stage2_unmap(struct kvm_pgtable *pgt, u64 addr, u64 size);
>
> +/**
> + * kvm_pgtable_stage2_wrprotect() - Write-protect guest stage-2 address range
> + * without TLB invalidation.
> + * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init().
> + * @addr: Intermediate physical address from which to write-protect,
> + * @size: Size of the range.
> + *
> + * Note that it is the caller's responsibility to invalidate the TLB after
> + * calling this function to ensure that the updated permissions are visible
> + * to the CPUs.
> + *
> + * Return: 0 on success, negative error code on failure.
> + */
> +int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size);
> +
> /**
> * kvm_pgtable_stage2_mkyoung() - Set the access flag in a page-table entry.
> * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init().
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 30713eb773e0..c218651f8eba 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -726,6 +726,12 @@ static int stage2_update_leaf_attrs(struct kvm_pgtable *pgt, u64 addr,
> return 0;
> }
>
> +int kvm_pgtable_stage2_wrprotect(struct kvm_pgtable *pgt, u64 addr, u64 size)
> +{
> + return stage2_update_leaf_attrs(pgt, addr, size, 0,
> + KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W, NULL);
> +}
> +
> kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
> {
> kvm_pte_t pte = 0;
>

Thanks,
Gavin