[PATCH 04/17] KVM: arm64: Replace fault_is_perm with a helper

[Fuad Tabba]

On Mon, 16 Mar 2026 at 17:55, Marc Zyngier <maz at kernel.org> wrote:
>
> Carrying a boolean to indicate that a given fault is slightly odd,
> as this is a property of the fault itself, and we'd better avoid
> duplicating state.
>
> For this purpose, introduce a kvm_s2_fault_is_perm() predicate that
> can take a fault descriptor as a parameter. fault_is_perm is therefore
> dropped from kvm_s2_fault.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>

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

Cheers,
/fuad

> ---
>  arch/arm64/kvm/mmu.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 2a7128b8dd14f..1b32f2e6c3e61 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1711,8 +1711,6 @@ static short kvm_s2_resolve_vma_size(const struct kvm_s2_fault_desc *s2fd,
>  }
>
>  struct kvm_s2_fault {
> -       bool fault_is_perm;
> -
>         bool write_fault;
>         bool exec_fault;
>         bool writable;
> @@ -1732,6 +1730,11 @@ struct kvm_s2_fault {
>         vm_flags_t vm_flags;
>  };
>
> +static bool kvm_s2_fault_is_perm(const struct kvm_s2_fault_desc *s2fd)
> +{
> +       return kvm_vcpu_trap_is_permission_fault(s2fd->vcpu);
> +}
> +
>  static int kvm_s2_fault_get_vma_info(const struct kvm_s2_fault_desc *s2fd,
>                                      struct kvm_s2_fault *fault)
>  {
> @@ -1888,7 +1891,7 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd,
>         if (s2fd->nested)
>                 adjust_nested_exec_perms(kvm, s2fd->nested, &fault->prot);
>
> -       if (!fault->fault_is_perm && !fault->s2_force_noncacheable && kvm_has_mte(kvm)) {
> +       if (!kvm_s2_fault_is_perm(s2fd) && !fault->s2_force_noncacheable && kvm_has_mte(kvm)) {
>                 /* Check the VMM hasn't introduced a new disallowed VMA */
>                 if (!fault->mte_allowed)
>                         return -EFAULT;
> @@ -1905,6 +1908,7 @@ static phys_addr_t get_ipa(const struct kvm_s2_fault *fault)
>  static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd,
>                             struct kvm_s2_fault *fault, void *memcache)
>  {
> +       bool fault_is_perm = kvm_s2_fault_is_perm(s2fd);
>         struct kvm *kvm = s2fd->vcpu->kvm;
>         struct kvm_pgtable *pgt;
>         int ret;
> @@ -1922,7 +1926,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd,
>          */
>         if (fault->vma_pagesize == PAGE_SIZE &&
>             !(fault->force_pte || fault->s2_force_noncacheable)) {
> -               if (fault->fault_is_perm && fault->fault_granule > PAGE_SIZE) {
> +               if (fault_is_perm && fault->fault_granule > PAGE_SIZE) {
>                         fault->vma_pagesize = fault->fault_granule;
>                 } else {
>                         fault->vma_pagesize = transparent_hugepage_adjust(kvm, s2fd->memslot,
> @@ -1936,7 +1940,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd,
>                 }
>         }
>
> -       if (!fault->fault_is_perm && !fault->s2_force_noncacheable && kvm_has_mte(kvm))
> +       if (!fault_is_perm && !fault->s2_force_noncacheable && kvm_has_mte(kvm))
>                 sanitise_mte_tags(kvm, fault->pfn, fault->vma_pagesize);
>
>         /*
> @@ -1944,7 +1948,7 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd,
>          * permissions only if fault->vma_pagesize equals fault->fault_granule. Otherwise,
>          * kvm_pgtable_stage2_map() should be called to change block size.
>          */
> -       if (fault->fault_is_perm && fault->vma_pagesize == fault->fault_granule) {
> +       if (fault_is_perm && fault->vma_pagesize == fault->fault_granule) {
>                 /*
>                  * Drop the SW bits in favour of those stored in the
>                  * PTE, which will be preserved.
> @@ -1977,7 +1981,6 @@ static int user_mem_abort(const struct kvm_s2_fault_desc *s2fd)
>         bool write_fault = kvm_is_write_fault(s2fd->vcpu);
>         bool logging_active = memslot_is_logging(s2fd->memslot);
>         struct kvm_s2_fault fault = {
> -               .fault_is_perm = perm_fault,
>                 .logging_active = logging_active,
>                 .force_pte = logging_active,
>                 .prot = KVM_PGTABLE_PROT_R,
> --
> 2.47.3
>