[PATCH 06/17] KVM: arm64: Kill write_fault from kvm_s2_fault

[Fuad Tabba]

On Mon, 16 Mar 2026 at 17:55, Marc Zyngier <maz at kernel.org> wrote:
>
> We already have kvm_is_write_fault() as a predicate indicating
> a S2 fault on a write, and we're better off just using that instead
> of duplicating the state.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kvm/mmu.c | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 12c2f0aeaae4c..86950acbd7e6b 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1711,7 +1711,6 @@ static short kvm_s2_resolve_vma_size(const struct kvm_s2_fault_desc *s2fd,
>  }
>
>  struct kvm_s2_fault {
> -       bool write_fault;
>         bool exec_fault;
>         bool writable;
>         bool topup_memcache;
> @@ -1799,7 +1798,7 @@ static int kvm_s2_fault_pin_pfn(const struct kvm_s2_fault_desc *s2fd,
>                 return ret;
>
>         fault->pfn = __kvm_faultin_pfn(s2fd->memslot, get_canonical_gfn(s2fd, fault),
> -                                      fault->write_fault ? FOLL_WRITE : 0,
> +                                      kvm_is_write_fault(s2fd->vcpu) ? FOLL_WRITE : 0,
>                                        &fault->writable, &fault->page);
>         if (unlikely(is_error_noslot_pfn(fault->pfn))) {
>                 if (fault->pfn == KVM_PFN_ERR_HWPOISON) {
> @@ -1850,7 +1849,7 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd,
>                          */
>                         fault->s2_force_noncacheable = true;
>                 }
> -       } else if (fault->logging_active && !fault->write_fault) {
> +       } else if (fault->logging_active && !kvm_is_write_fault(s2fd->vcpu)) {
>                 /*
>                  * Only actually map the page as writable if this was a write
>                  * fault.
> @@ -1980,21 +1979,17 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd,
>  static int user_mem_abort(const struct kvm_s2_fault_desc *s2fd)
>  {
>         bool perm_fault = kvm_vcpu_trap_is_permission_fault(s2fd->vcpu);
> -       bool write_fault = kvm_is_write_fault(s2fd->vcpu);
>         bool logging_active = memslot_is_logging(s2fd->memslot);
>         struct kvm_s2_fault fault = {
>                 .logging_active = logging_active,
>                 .force_pte = logging_active,
>                 .prot = KVM_PGTABLE_PROT_R,
> -               .write_fault = write_fault,
>                 .exec_fault = kvm_vcpu_trap_is_exec_fault(s2fd->vcpu),
> -               .topup_memcache = !perm_fault || (logging_active && write_fault),
> +               .topup_memcache = !perm_fault || (logging_active && kvm_is_write_fault(s2fd->vcpu)),
>         };
>         void *memcache;
>         int ret;
>
> -       VM_WARN_ON_ONCE(fault.write_fault && fault.exec_fault);
> -

We can't hit this warning anyway.

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

Cheers,
/fuad

>         /*
>          * Permission faults just need to update the existing leaf entry,
>          * and so normally don't require allocations from the memcache. The
> --
> 2.47.3
>