[RFC PATCH v3 09/16] KVM: arm64: Use separate function for the mapping size in user_mem_abort()

[Haibo Xu]

On Wed, 28 Oct 2020 at 01:26, Alexandru Elisei <alexandru.elisei at arm.com> wrote:
>
> user_mem_abort() is already a long and complex function, let's make it
> slightly easier to understand by abstracting the algorithm for choosing the
> stage 2 IPA entry size into its own function.
>
> This also makes it possible to reuse the code when guest SPE support will
> be added.
>

Better to mention that there is "No functional change"!

> Signed-off-by: Alexandru Elisei <alexandru.elisei at arm.com>
> ---
>  arch/arm64/kvm/mmu.c | 55 ++++++++++++++++++++++++++------------------
>  1 file changed, 33 insertions(+), 22 deletions(-)
>
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 19aacc7d64de..c3c43555490d 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -738,12 +738,43 @@ transparent_hugepage_adjust(struct kvm_memory_slot *memslot,
>         return PAGE_SIZE;
>  }
>
> +static short stage2_max_pageshift(struct kvm_memory_slot *memslot,
> +                                 struct vm_area_struct *vma, hva_t hva,
> +                                 bool *force_pte)
> +{
> +       short pageshift;
> +
> +       *force_pte = false;
> +
> +       if (is_vm_hugetlb_page(vma))
> +               pageshift = huge_page_shift(hstate_vma(vma));
> +       else
> +               pageshift = PAGE_SHIFT;
> +
> +       if (memslot_is_logging(memslot) || (vma->vm_flags & VM_PFNMAP)) {
> +               *force_pte = true;
> +               pageshift = PAGE_SHIFT;
> +       }
> +
> +       if (pageshift == PUD_SHIFT &&
> +           !fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
> +               pageshift = PMD_SHIFT;
> +
> +       if (pageshift == PMD_SHIFT &&
> +           !fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE)) {
> +               *force_pte = true;
> +               pageshift = PAGE_SHIFT;
> +       }
> +
> +       return pageshift;
> +}
> +
>  static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>                           struct kvm_memory_slot *memslot, unsigned long hva,
>                           unsigned long fault_status)
>  {
>         int ret = 0;
> -       bool write_fault, writable, force_pte = false;
> +       bool write_fault, writable, force_pte;
>         bool exec_fault;
>         bool device = false;
>         unsigned long mmu_seq;
> @@ -776,27 +807,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
>                 return -EFAULT;
>         }
>
> -       if (is_vm_hugetlb_page(vma))
> -               vma_shift = huge_page_shift(hstate_vma(vma));
> -       else
> -               vma_shift = PAGE_SHIFT;
> -
> -       if (logging_active ||
> -           (vma->vm_flags & VM_PFNMAP)) {
> -               force_pte = true;
> -               vma_shift = PAGE_SHIFT;
> -       }
> -
> -       if (vma_shift == PUD_SHIFT &&
> -           !fault_supports_stage2_huge_mapping(memslot, hva, PUD_SIZE))
> -              vma_shift = PMD_SHIFT;
> -
> -       if (vma_shift == PMD_SHIFT &&
> -           !fault_supports_stage2_huge_mapping(memslot, hva, PMD_SIZE)) {
> -               force_pte = true;
> -               vma_shift = PAGE_SHIFT;
> -       }
> -
> +       vma_shift = stage2_max_pageshift(memslot, vma, hva, &force_pte);
>         vma_pagesize = 1UL << vma_shift;
>         if (vma_pagesize == PMD_SIZE || vma_pagesize == PUD_SIZE)
>                 fault_ipa &= ~(vma_pagesize - 1);
> --
> 2.29.1
>
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